National Academies Press: OpenBook

Cryptography's Role in Securing the Information Society (1996)

Chapter: Policy Options for the Future

« Previous: Part III - Policy Options, Findings, and Recommendations
Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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7 Policy Options for the Future

Current national cryptography policy defines only one point in the space of possible policy options. A major difficulty in the public debate over cryptography policy has been incomplete explanation of why the government has rejected certain policy options. Chapter 7 explores a number of possible alternatives to current national cryptography policy, selected by the committee either because they address an important dimension of national cryptography policy or because they have been raised by a particular set of stakeholders. Although in the committee's judgment these alternatives deserve analysis, it does not follow that they necessarily deserve consideration for adoption. The committee's judgments about appropriate policy options are discussed in Chapter 8.

7.1 EXPORT CONTROL OPTIONS FOR CRYPTOGRAPHY

7.1.1 Dimensions of Choice for Controlling the Export of Cryptography

An export control regime—a set of laws and regulations governing what may or may not be exported under any specified set of circumstances—has many dimensions that can be considered independently. These dimensions include:

• The type of export license granted. Three types of export licenses are available:

—A general license, under which export of an item does not in gen-

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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eral require prior government approval but nonetheless is tracked under an export declaration;

—A special license, under which prior government approval is required but which allows multiple and continuing transactions under one license validation; and

—An individual license, under which prior government approval is required for each and every transaction.

As a general rule, only individual licenses are granted for the export of items on the U.S. Munitions List, which includes ''strong" cryptography.1

• The strength of a product's cryptographic capabilities. Current policy recognizes the difference between RC2/RC4 algorithms using 40-bit keys and other types of cryptography, and places fewer and less severe restrictions on the former.

• The default encryption settings on the delivered product. Encryption can be tacitly discouraged, but not forbidden, by the use of appropriate settings.2

• The type of product. Many different types of products can incorporate encryption capabilities. Products can be distinguished by medium (e.g., hardware vs. software) and/or intended function (e.g., computer vs. communications).

• The extent and nature of features that allow exceptional access. The Administration has suggested that it would permit the export of encryption software with key lengths of 64 bits or less if the keys were "properly escrowed."3 Thus, inclusion in a product of a feature for exceptional access could be made one condition for allowing the export of that product. In addition, the existence of specific institutional arrangements (e.g., which specific parties would hold the information needed to implement exceptional access) might be made a condition for the export of these products.

• The ultimate destination or intended use of the delivered product. U.S.

1 However, as noted in Chapter 4, the current export control regime for cryptography involves a number of categorical exemptions as well as some uncodified "in-practice" exemptions.

2 Software, and even software-driven devices, commonly have operational parameters that can be selected or set by a user. An example is the fax machine that allows many user choices to be selected by keyboard actions. The parameters chosen by a manufacturer before it ships a product are referred to as the "defaults" or "default condition." Users are generally able to alter such parameters at will.

3 At the time of this writing, the precise definition of "properly escrowed" is under debate and review in the Administration. The most recent language on this definition as of December 1995 is provided in Chapter 5.

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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export controls have long distinguished between exports to "friendly" and "hostile" nations. In addition, licenses have been granted for the sale of certain controlled products only when a particular benign use (e.g., financial transactions) could be certified. A related consideration is the extent to which nations cooperate with respect to re-export of a controlled product and/or export of their own products. For example, CoCom member nations4 in principle agreed to joint controls on the export of certain products to the Eastern bloc; as a result, certain products could be exported to CoCom member nations much more easily than to other nations.

At present, there are few clear guidelines that enable vendors to design a product that will have a high degree of assurance of being exportable (Chapters 4 and 6). Table 7.1 describes various mechanisms that might be used to manage the export of products with encryption capabilities.

This remainder of Section 7.1 describes a number of options for controlling the export of cryptography, ranging from the sweeping to the detailed.

7.1.2 Complete Elimination of Export Controls on Cryptography

The complete elimination of export controls (both the USML and the Commerce Control List controls) on cryptography is a proposal that goes beyond most made to date, although certainly such a position has advocates. If export controls on cryptography were completely eliminated, it is possible that within a short time most information technology products exported from the United States would have encryption capabilities. It would be difficult for the U.S. government to influence the capabilities of these products, or even to monitor their deployment and use worldwide, because numerous vendors would most probably be involved.

Note, however, that the simple elimination of U.S. export controls on cryptography does not address the fact that other nations may have import controls and/or restrictions on the use of cryptography internally. Furthermore, it takes time to incorporate products into existing infrastructures, and slow market growth may encourage some vendors to take their time in developing new products. Thus, simply eliminating U.S. export controls on cryptography would not ensure markets abroad for U.S. products with encryption capabilities; indeed, the elimination of U.S.

4 CoCom refers to the Coordinating Committee, a group of Western nations (and Japan) that agreed to a common set of export control practices during the Cold War to control the export of militarily useful technologies to Eastern bloc nations. CoCom was disbanded in March 1994, and a successor regime known as the New Forum is being negotiated as this report is being written.

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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TABLE 7.1 Mechanisms of Export Management

Type

Description

When Appropriate

Total embargo

All or most exports of cryptography to target country prohibited (this would be more restrictive than today's regime). Hypothetical example: no products with encryption capabilities can be exported to Vietnam, Libya, Iraq, Iran.

Appropriate during wartime or other acute national emergency or when imposed pursuant to United Nations or other broad international effort.

Selective export prohibitions

Certain products with encryption capabilities barred for export to target country. Hypothetical example: nothing cryptographically stronger than40-bit RC4 can be exported to South Africa.

Appropriate when supplier countries agree on items for denial and cooperate on restrictions.

Selective activity prohibitions

Exports of cryptography for use in particular activities in target country prohibited. Hypothetical example: PGP allowed for export to pro- democracy groups in People's Republic of China but not for government use.

Appropriate when supplier countries identify proscribed operations and agree to cooperate on restrictions.

Transactional licensing

Products with encryption capabilities require government agency licensing for export to a particular country or country group. Hypothetical example: State Department individual validated license for a DES encryption product. Licensing actions may be conditioned on end-use verification or postexport verification.

Appropriate when product is inherently sensitive for export to any destination, or when items have both acceptable and undesired potential applications. Also requires an effective multilateral control regime

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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Bulk licensing

Exporter obtains government authority to export categories of products with encryption capabilities to particular consignees for a specified time period. Hypothetical examples: Commerce Department distribution license, ITAR foreign manufacturing license. Note that categories can be determined with considerable freedom. Enforcement may rely on after-the-fact audits.

Same as preceding circumstances, but when specific transaction facts are not critical to effective export control.

Preexport notification

Exporter must prenotify shipment; government agency may prohibit, impose conditions, or exercise persuasion. Hypothetical example: requirement imposed on vendors of products with encryption capabilities to notify the U.S. government prior to shipping product overseas.

Generally regarded as an inappropriate export control measure because exporter cannot accept last-minute uncertainty.

Conditions on general authority or right to export

Exporter not required to obtain government agency license but must meet regulatory conditions that preclude high-risk exports. (In general, 40-bit RC2/RC4 encryption falls into this category once the Commodity Jurisdiction procedure has determined that a particular product with encryption capabilities may be governed by the CCL. Hypothetical example: Commerce Department general licenses.

Appropriate when risk of diversion or undesired use is low.

Postexport recordkeeping

While no license may be necessary, exporter must keep records of particulars of exports for specified period and submit or make available to government agency. Hypothetical example: vendor is required to keep records of foreign sales of 40-bit RC2/RC4 encryption products under a Shippers Export Declaration.

Appropriate when it is possible to monitor exports of weak cryptography for possible diversion.

SOURCE: Adapted from National Research Council, Finding Common Ground: U.S. Export Controls in a Changed Global Environment, National Academy Press, Washington, D.C., 1990, p. 109.

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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export controls could in itself stimulate foreign nations to impose import controls more stringently. Appendix G contains more discussion of these issues.

The worldwide removal of all controls on the export, import, and use of products with encryption capabilities would likely result in greater standardization of encryption techniques. Standardization brought about in this manner would result in:

• Higher degrees of international interoperability of these products;

• Broader use, or at least more rapid spread, of encryption capabilities as the result of the strong distribution capabilities of U.S. firms;

• Higher levels of confidentiality, as a result of greater ease in adopting more powerful algorithms and longer keys as standards; and

• Greater use of cryptography by hostile, criminal, and unfriendly parties as they, too, begin to use commercial products with strong encryption capabilities.

On the other hand, rapid, large-scale standardization would be unlikely unless a few integrated software products with encryption capabilities were able to achieve worldwide usage very quickly. Consider, for example, that although there are no restrictions on domestic use of cryptography in the United States, interoperability is still difficult, in many cases owing to variability in the systems in which the cryptography is embedded.  Likewise, many algorithms stronger than DES are well known, and there are no restrictions in place on the domestic use of such algorithms, and yet only DES even remotely approaches common usage (and not all DES-based applications are interoperable).

For reasons well articulated by the national security and law enforcement communities (see Chapter 3) and accepted by the committee, the complete elimination of export controls on products with encryption capabilities does not seem reasonable in the short term. Whether export controls will remain feasible and efficacious in the long term has yet to be seen, although clearly, maintaining even their current level of effectiveness will become increasingly difficult.

7.1.3 Transfer of All Cryptography Products to the Commerce Control List

As discussed in Chapter 4, the Commerce Control List (CCL) complements the U.S. Munitions List (USML) in controlling the export of cryptography. (Box 4.2 in Chapter 4 describes the primary difference between the USML and the CCL.) In 1994, Representative Maria Cantwell (D-Washington) introduced legislation to transfer all mass-market software products involving cryptographic functions to the CCL. Although this

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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legislation never passed, it resulted in the promise and subsequent delivery of an executive branch report on the international market for computer software with encryption.5

The Cantwell bill was strongly supported by the software industry because of the liberal consideration afforded products controlled for export by the CCL. Many of the bill's advocates believed that a transfer of jurisdiction to the Commerce Department would reflect an explicit recognition of cryptography as a commercial technology that should be administered under a dual-use export control regime. Compared to the USML, they argued that the CCL is a more balanced regime that still has considerable effectiveness in limiting exports to target destinations and end users.

On the other hand, national security officials regard the broad authorities of the Arms Export Control Act (AECA) as essential to the effective control of encryption exports. The AECA provides authority for case-by-case regulation of exports of cryptography to all destinations, based on national security considerations. In particular, licensing decisions are not governed by factors such as the country of destination, end users, end uses, or the existence of bilateral or multilateral agreements that often limit the range of discretionary action possible in controlling exports pursuant to the Export Administration Act. Further, the national security provisions of the AECA provide a basis for classifying the specific rationale for any particular export licensing decision made under its authority, thus protecting what may be very sensitive information about the particular circumstances surrounding that decision.

Although sympathetic to the Cantwell bill's underlying rationale, the committee believes that the bill does not address the basic dilemma of cryptography policy. As acknowledged by some of the bill's supporters, transfer of a product's jurisdiction to the CCL does not mean automatic decontrol of the product, and national security authorities could still have considerable input into how exports are actually licensed. In general, the committee believes that the idea of split jurisdiction, in which some types of cryptography are controlled under the CCL and others under the USML, makes considerable sense given the various national security implications of widespread use of encryption. However, where the split should be made is a matter of discussion; the committee expresses its own judgments on this point in Chapter 8.

5 Department of Commerce and National Security Agency, A Study of the International Market for Computer Software with Encryption, prepared for the Interagency Working Group on Encryption and Telecommunications Policy, Office of the Secretary of Commerce, released January 11, 1996.

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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7.1.4 End-use Certification

Explicitly exempted under the current International Traffic in Arms Regulations (ITAR) is the export of cryptography for ensuring the confidentiality of financial transactions, specifically for cryptographic equipment and software that are "specially designed, developed or modified for use in machines for banking or money transactions, and restricted to use only in such transactions."6 In addition, according to senior National Security Agency (NSA) officials, cryptographic systems, equipment, and software are in general freely exportable for use by U.S.-controlled foreign companies and to banking and financial institutions for purposes other than financial transactions, although NSA regards these approvals as part of the case-by-case review associated with equipment and products that do not enjoy an explicit exemption in the ITAR.

In principle, the ITAR could explicitly exempt products with encryption capabilities for use by foreign subsidiaries of U.S. companies, foreign companies that are U.S.-controlled, and banking and financial institutions. Explicit "vertical" exemptions for these categories could do much to alleviate confusion among users, many of whom are currently uncertain about what cryptographic protection they may be able to use in their international communications, and could enable vendors to make better informed judgments about the size of a given market.

Specific vertical exemptions could also be made for different industries (e.g., health care or manufacturing) and perhaps for large foreignowned companies that would be both the largest potential customers and the parties most likely to be responsible corporate citizens. Inhibiting the diversion to other uses of products with encryption capabilities sold to these companies could be the focus of explicit contractual language binding the recipient to abide by certain terms that would be required of any vendor as a condition of sale to a foreign company, as it is today under USML procedures under the ITAR. Enforcement of end-use restrictions is discussed in Chapter 4.

7.1.5 Nation-by-Nation Relaxation of Controls and Harmonization of U.S. Export Control Policy on Cryptography with Export/Import Policies of Other Nations

The United States could give liberal export consideration to products with encryption capabilities intended for sale to recipients in a select set of nations;7 exports to nations outside this set would be restricted. Na-

6 International Traffic in Arms Regulations, Section 121.1, Category XIII (b)(1)(ii).

7 For example, products with encryption capabilities can be exported freely to Canada without the need of a USML export license if intended for domestic Canadian use.

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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tions in the select set would be expected to have a more or less uniform set of regulations to control the export of cryptography, resulting in a more level playing field for U.S. vendors. In addition, agreements would be needed to control the re-export of products with encryption capabilities outside this set of nations.

Nation-by-nation relaxation of controls is consistent with the fact that different countries generally receive different treatment under the U.S. export control regime for military hardware. For example, exports of U.S. military hardware have been forbidden to some countries because they were terrorist nations, and to others because they failed to sign the nuclear nonproliferation treaty. A harmonization of export control regimes for cryptography would more closely resemble the former CoCom approach to control dual-use items than the approach reflected in the unilateral controls on exports imposed by the USML.

From the standpoint of U.S. national security and foreign policy, a serious problem with harmonization is the fact that the relationship between the United States and almost all other nations has elements of both competition and cooperation that may change over time. The widespread use of U.S. products with strong encryption capabilities under some circumstances could compromise U.S. positions with respect to these competitive elements, although many of these nations are unlikely to use U.S. products with encryption capabilities for their most sensitive communications.

Finally, as is true for other proposals to liberalize U.S. export controls on cryptography, greater liberalization may well cause some other nations to impose import controls where they do not otherwise exist. Such an outcome would shift the onus for impeding vendor interests away from the U.S. government; however, depending on the nature of the resulting import controls, U.S. vendors of information technology products with encryption capabilities might be faced with the need to conform to a multiplicity of import control regimes established by different nations.

7.1.6 Liberal Export for Strong Cryptography with Weak Defaults

An export control regime could grant liberal export consideration to products with encryption capabilities designed in such a way that the defaults for usage result in weak or nonexistent encryption (Box 7.1), but also so that users could invoke options for stronger encryption through an affirmative action.

For example, such a product might be a telephone designed for endto-end security. The default mode of operation could be set in two different ways. One way would be for the telephone to establish a secure connection if the called party has a comparable unit. The second way

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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BOX 7.1
Possible Examples of Weak Encryption Defaults

• The product does not specify a minimum password length. Many users will generate short, and thus poor or weak, passwords.

• The product does not perform link encryption automatically. The user on either side of the communication link must select an option explicitly to encrypt the communications before encryption happens.

• The product requires user key generation rather than simple passwords and retains a user key or generates a record of one. Users might well accidentally compromise it and make it available, even if they had the option to delete it.

• The product generates a key and instructs the user to register it.

• E-mail encryption is not automatic. The sender must explicitly select an encryption option to encrypt messages.

would be for the telephone always to establish an insecure connection; establishing a secure connection would require an explicit action by the user. All experience suggests that the second way would result in far fewer secure calls than the first way.8

An export policy favoring the export of encryption products with weak defaults benefits the information-gathering needs of law enforcement and signals intelligence efforts because of user psychology. Many people, criminals and foreign government workers included, often make mistakes by using products "out of the box" without any particular attempt to configure them properly. Such a policy could also take advantage of the distribution mechanisms of the U.S. software industry to spread weaker defaults.

Experience to date suggests that good implementations of cryptography for confidentiality are transparent and automatic and thus do not require positive user action. Such implementations are likely to be chosen by organizations that are most concerned about confidentiality and that have a staff dedicated to ensuring confidentiality (e.g., by resetting weak vendor-supplied defaults). End users that obtain their products with encryption capabilities on the retail store market are the most likely to be affected by this proposal, but such users constitute a relatively small part of the overall market.

8 Of course, other techniques can be used to further discourage the use of secure modes. For example, the telephone could be designed to force the user to wait several seconds for establishment of the secure mode.

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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7.1.7 Liberal Export for Cryptographic Applications Programming Interfaces

A cryptographic applications programming interface (CAPI; see Appendix K) is a well-defined boundary between a baseline product (such as an operating system, a database management program, or a word processing program) and a cryptography module that provides a secure set of cryptographic services such as authentication, digital signature generation, random number generation, and stream or block mode encryption. The use of a CAPI allows vendors to support cryptographic functions in their products without actually providing them at distribution.

Even though such products have no cryptographic functionality per se and are therefore not specifically included in Category XIII of the ITAR (see Appendix N), license applications for the export of products incorporating CAPIs have in general been denied. The reason is that strong cryptographic capabilities could be deployed on a vast scale if U.S. vendors exported applications supporting a common CAPI and a foreign vendor then marketed an add-in module with strong encryption capabilities.9

To meet the goals of less restrictive export controls, liberal export consideration could be given to products that incorporate a CAPI designed so that only "certified" cryptographic modules could be incorporated into and used by the application. That is, the application with the CAPI would have to ensure that the CAPI would work only with certified cryptographic modules. This could be accomplished by incorporating into the application a check for a digital signature whose presence would indicate that the add-on cryptographic module was indeed certified; if and only if such a signature were detected by the CAPI would the product allow use of the module.

One instantiation of a CAPI is the CAPI built into applications that use the Fortezza card (discussed in Chapter 5). CAPI software for Fortezza is available for a variety of operating systems and PC-card reader types; such software incorporates a check to ensure that the device being used is itself a Fortezza card. The Fortezza card contains a private Digital Signature Standard (DSS) key that can be used to sign a challenge from the workstation. The corresponding DSS public key is made available in the

9 This discussion refers only to "documented" or "open" CAPIs, i.e., CAPIs that are accessible to the end user. Another kind of CAPI is "undocumented" and "closed"; that is, it is inaccessible to the end user, though it is used by system developers for their own convenience. While a history of export licensing decisions and practices supports the conclusion that most products implementing "open'' CAPIs will not receive export licenses, history provides no consistent guidance with respect to products implementing CAPIs that are inaccessible to the end user.

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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BOX 7.2
The Microsoft CrytoAPI

In June 1995, Microsoft received commodity jurisdiction (CJ) to the Commerce Control List (CCL) for Windows NT with CryptoAPI (a Microsoft trademark) plus a 'base' cryto-module that qualifies for CCL jurisdiction under present regulations (i.e., it uses a 40-bit RC4 algorithm for confidentiality); a similar CJ application for Windows '95 is pending. The 'base' crypto-module can be supplemented by a crypto-module provided by some other vendor of crytography, but the cryptographic applications programming interface within the operating system will function only with crypto-modules that have been digitally signed by Microsoft, which will provide a digital signature for a cryto-module only if the cryto-module vendor certifies that it (the module vendor) will comply with all relevant U.S. export control regulations. (In the case of a crypto-module for sale in the United States only, Microsoft will provide a digital signature upon the module vendor's statement to that effect.)

Responsibility for complying with export control regulations on cryptography is as follows:

• Windows NT (and Windows '95, should the pending application be successful) qualify for CCL jurisdiction on the basis of a State Department export licensing decision.

• Individual crypto-modules are subject to a case-by-case licensing analysis, and the cryptography vendor is responsible for compliance.

• Applications that use Windows NT or Windows '95 for cryptographic services should not be subject to export control regulations on cryptography. At the time of this writing, Microsoft is seeking an advisory opinion to this effect so that applications vendors do not need to submit a request for a CJ cryptography licensing decision.

CAPI, and thus the CAPI is able to verify the authenticity of the Fortezza card.

A second approach to the use of a CAPI has been proposed by Microsoft and is now eligible foror liberal export consideration by the State Department (Box 7.2). The Microsoft approach involves three components: an operating system with a CAPI embedded within it, modules providing cryptographic services through the CAPI, and applications that can call on the modules through the CAPI provided by the operating system. In principle, each of these components is the responsibility of different parties: Microsoft is responsible for the operating system, cryptography vendors are responsible for the modules, and independent applications vendors are responsible for the applications that run on the operating system.

From the standpoint of national security authorities, the effectiveness of an approach based on the use of a certified CAPI/module combination depends on a number of factors. For example, the product incorporating

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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the CAPI should be known to be implemented in a manner that enforces the appropriate constraints on crypto-modules that it calls; furthermore, the code that provides such enforcement should not be trivially bypassed. The party certifying the crypto-module should protect the private signature key used to sign it. Vendors would still be required to support domestic and exportable versions of an application if the domestic version was allowed to use any module while the export version was restricted in the set of modules that would be accepted, although the amount of effort required to develop these two different versions would be quite small.

The use of CAPIs that check for appropriate digital signatures would shift the burden for export control from the applications or systems vendors to the vendors of the cryptographic modules. This shift could benefit both the government and vendors because of the potential to reduce the number of players engaged in the process. For example, all of the hundreds of e-mail applications on the market could quickly support encrypted e-mail by supporting a CAPI developed by a handful of software and/or hardware cryptography vendors. The cryptography vendors would be responsible for dealing with the export and import controls of various countries, leaving e-mail application vendors to export freely anywhere in the world. Capabilities such as escrowed encryption could be supported within the cryptography module itself, freeing the applications or system vendor from most technical, operational, and political issues related to export control.

A trustworthy CAPI would also help to support cryptography policies that might differ among nations. In particular, a given nation might specify certain performance requirements for all cryptography modules used or purchased within its borders.10 International interoperability

10 An approach to this effect is the thrust of a proposal from Hewlett-Packard. The Hewlett-Packard International Cryptography Framework (ICF) proposal includes a stamp size "policy card" (smart card) that would be inserted into a cryptographic unit that is a part of a host system. Cryptographic functions provided within the cryptographic unit could be executed only with the presence of a valid policy card. The policy card could be configured to enable only those cryptographic functions that are consistent with government export and local policies. The "policy card" allows for managing the use of the integrated cryptography down to the application-specific level. By obtaining a new policy card, customers could be upgraded to take advantage of varying cryptographic capabilities as government policies or organizational needs change. As part of an ICF solution, a network security server could be implemented to provide a range of different security services, including verification of the other three service elements (the card, the host system, the cryptographic unit). Sources: Carl Snyder, Hewlett-Packard, testimony to the NRC committee in February 1995; Hewlett-Packard, International Cryptography Framework White Paper, February 1994.

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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problems resulting from conflicting national cryptography policies would still remain.

7.1.8 Liberal Export for Escrowable Products with Encryption Capabilities

As discussed in Chapter 5, the Administration's proposal of August 17, 1995, would allow liberal export consideration for software products with encryption capabilities whose keys are "properly escrowed." In other words, strong cryptography would be enabled for these products only when the keys were escrowed with appropriate escrow agents.

An escrowed encryption product differs from what might be called an "escrowable" product. Specifically, an escrowed encryption product is one whose key must be escrowed with a registered, approved agent before the use of (strong) cryptography can be enabled, whereas an escrowable product is one that provides full cryptographic functionality that includes optional escrow features for the user. The user of an escrowable product can choose whether or not to escrow the relevant keys, but regardless of the choice, the product still provides its full suite of encryption capabilities.11

Liberal export consideration for escrowable products could be granted and incentives promulgated to encourage the use of escrow features. While the short-term disadvantage of this approach from the standpoint of U.S. national security is that it allows encryption stronger than the current 40-bit RC2/RC4 encryption allowed under present regulations to diffuse into foreign hands, it has the long-term advantage of providing foreign governments with a tool for influencing or regulating the use of cryptography as they see fit. Currently, most products with encryption capabilities do not have built-in features to support escrow built into them. However, if products were designed and exported with such features, governments would have a hook for exercising some influence. Some governments might choose to require the escrowing of keys, while others might simply provide incentives to encourage escrowing. In any event, the diffusion of escrowable products abroad would raise the awareness of foreign governments, businesses, and individuals about encryption and thus lay a foundation for international cooperation on the formulation of national cryptography policies.

11 For example, an escrowable product would not enable the user to encrypt files with passwords. Rather, the installation of the product would require the user to create a key or set of named keys, and these keys would be used when encrypting files. The installation would also generate a protected "safe copy" of the keys with instructions to users that they should register the key "somewhere." It would be up to the users to decide where or whether to register the keys.

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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7.1.9 Alternatives to Government Certification of Escrow Agents Abroad

As discussed in Chapter 5, the Administration's August 1995 proposal focuses on an implementation of escrowed encryption that involves the use of "escrow agents certified by the U.S. government or by foreign governments with which the U.S. government has formal agreements consistent with U.S. law enforcement and national security requirements."12 This approach requires foreign customers of U.S. escrowed encryption products to use U.S. escrow agents until formal agreements can be negotiated that specify the responsibilities of foreign escrow agents to the United States for law enforcement and national security purposes.

Skeptics ask what incentives the U.S. government would have to conclude the formal agreements described in the August 1995 proposal if U.S. escrow agents would, by default, be the escrow agents for foreign consumers. They believe that the most likely result of adopting the Administration's proposal would be U.S. foot-dragging and inordinate delays in the consummation of formal agreements for certifying foreign escrow agents. Appendix G describes some of the U.S. government efforts to date to promote a dialogue on such agreements.

The approaches described below address problems raised by certifying foreign escrow agents:

• Informal arrangements for cooperation. One alternative is based on the fact that the United States enjoys strong cooperative law enforcement relationships with many nations with which it does not have formal agreements regarding cooperation. Negotiation of a formal agreement between the United States and another nation could be replaced by presidential certification that strong cooperative law enforcement relationships exist between the United States and that nation. Subsequent cooperation would be undertaken on the same basis that cooperation is offered today.

• Contractual key escrow. A second alternative is based on the idea that formal agreements between nations governing exchange of escrowed key information might be replaced by private contractual arrangements.13 A user that escrows key information with an escrow agent, wherever that agent is located, would agree contractually that the U.S. government would have access to that information under a certain set of carefully specified circumstances. A suitably designed exportable product would provide strong encryption only upon receipt of affirmative confirmation that the relevant key information had been deposited with escrow agents requiring such contracts with users. Alternatively, as a condition of sale,

12 See Box 5.3, Chapter 5.

13 Henry Perritt, "Transnational Key Escrow," paper presented at the International Cryptography Institute 1995 conference, Washington, D.C., September 22, 1995.

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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end users could be required to deposit keys with escrow agents subject to such a contractual requirement.

7.1.10 Use of Differential Work Factors in Cryptography

Differential work factor cryptography is an approach to cryptography that presents different work factors to different parties attempting to cryptanalyze a given piece of encrypted information.14Iris Associates, the creator of Notes, proposed such an approach for Lotus Notes Version 4 to facilitate its export, and the U.S. government has accepted it. Specifically, the international edition of Lotus Notes Version 4 is designed to present a 40-bit work factor to the U.S. government and a 64-bit work factor to all other parties. It implements this differential work factor by encrypting 24 bits of the 64-bit key with the public-key portion of an RSA key pair held by the U.S. government. Because the U.S. government can easily decrypt these 24 bits, it faces only a 40-bit work factor when it needs access to a communications stream overseas encrypted by the international edition. All other parties attempting to cryptanalyze a message face a 64-bit work factor.

Differential work factor cryptography is similar to partial key escrow (described in Chapter 5) in that both provide very strong protection against most attackers but are vulnerable to attack by some specifically chosen authority. However, they are different in that differential work factor cryptography does not require user interaction with an escrow agent, and so it can offer strong cryptography "out of the box." Partial key escrow offers all of the strengths and weaknesses of escrowed encryption, including the requirement that the enabling of strong cryptography does require interaction with an escrow agent.

7.1.11 Separation of Cryptography from Other Items on the U.S. Munitions List

As noted in Chapter 4, the inclusion of products with encryption capabilities on the USML puts them on a par with products intended for strictly military purposes (e.g., tanks, missiles). An export control regime that authorized the U.S. government to separate cryptography—a true dual-use technology—from strictly military items would provide much needed flexibility in dealing with nations on which the United States wishes to place sanctions.

14 Recall from Chapter 2 that a work factor is a measure of the amount of work that it takes to undertake a brute-force exhaustive cryptanalytic search.

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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7.2 ALTERNATIVES FOR PROVIDING GOVERNMENT EXCEPTIONAL ACCESS TO ENCRYPTED DATA

Providing government exceptional access to encrypted data is an issue with a number of dimensions, only some of which relate directly to encryption.

7.2.1 A Prohibition on the Use and Sale of Cryptography Lacking Features for Exceptional Access

One obvious approach to ensuring government exceptional access to encrypted information is to pass legislation that forbids the use of cryptography lacking features for such access, presumably with criminal penalties attached for violation. (Given that escrowed cryptography appears to be the most plausible approach to providing government exceptional access, the term "unescrowed cryptography" is used here as a synonym for cryptography without features for exceptional access.) Indeed, opponents of the Escrowed Encryption Standard (EES) and the Clipper chip have argued repeatedly that the EES approach would succeed only if alternatives were banned.15 Many concerns have been raised about the prospect of a mandatory prohibition on the use of unescrowed cryptography.

From a law enforcement standpoint, a legislative prohibition on the use of unescrowed encryption would have clear advantages. Its primary impact would be to eliminate the commercial supply of unescrowed products with encryption capabilities—vendors without a market would most likely not produce or distribute such products, thus limiting access of criminals to unescrowed encryption and increasing the inconvenience of evading a prohibition on the use of unescrowed encryption. At the same time, such a prohibition would leave law-abiding users with strong concerns about the confidentiality of their information being subject to procedures beyond their control.

A legislative prohibition on the use of unescrowed encryption also raises specific technical, economic, and legal issues.

Concerns About Personal Freedom

The Clinton Administration has stated that it has no intention of outlawing unescrowed cryptography, and it has repeatedly and explicitly disavowed any intent to regulate the domestic use of cryptography. How-

15 For example, see Electronic Privacy Information Center, press release, August 16, 1995, available on-line at http://www.epic.org.

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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ever, no administration can bind future administrations (a fact freely acknowledged by administration officials). Thus, some critics of the Administration position believe that the dynamics of the encryption problem may well drive the government—sooner or later—to prohibit the use of encryption without government access.16The result is that the Administration is simply not believed when it forswears any intent to regulate cryptography used in the United States. Two related concerns are raised:

• The "slippery slope." Many skeptics fear that current cryptography policy is the first step down a slippery slope toward a more restrictive policy regime under which government may not continue to respect limits in place at the outset. An oft-cited example is current use of the Social Security Number, which was not originally intended to serve as a universal identifier when the Social Security Act was passed in 1935 but has, over the last 50 years, come to serve exactly that role by default, simply because it was there to be exploited for purposes not originally intended by the enabling legislation.

• Misuse of deployed infrastructurefor cryptography. Many skeptics are concerned that a widely deployed infrastructure for cryptography could be used by a future administration or Congress to promulgate and/or enforce restrictive policies regarding the use of cryptography. With such an infrastructure in place, critics argue that a simple policy change might be able to transform a comparatively benign deployment of technology into an oppressive one. For example, critics of the Clipper proposal were concerned about the possibility that a secure telephone system with government exceptional access capabilities could, under a strictly voluntary program to encourage its purchase and use, achieve moderate market penetration. Such market penetration could then facilitate legislation outlawing all other cryptographically secure telephones.17

16 For example, Senator Charles Grassley (R-Iowa) introduced legislation (The Anti-Electronic Racketeering Act of 1995) on June 27, 1995, to "prohibit certain acts involving the use of computers in the furtherance of crimes." The proposed legislation makes it unlawful "to distribute computer software that encodes or encrypts electronic or digital communications to computer networks that the person distributing the software knows or reasonably should know, is accessible to foreign nationals and foreign governments, regardless of whether such software has been designated as nonexportable," except for software that uses "a universal decoding device or program that was provided to the Department of Justice prior to the distribution."

17 By contrast, a deployed infrastructure could have characteristics that would make it quite difficult to implement policy changes on a short time scale. For example, it would be very difficult to implement a policy change that would change the nature of the way in which people use today's telephone system. Not surprisingly, policy makers would prefer to work with infrastructures that are quickly responsive to their policy preferences.

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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BOX 7.3
Bobby Inman on the Classification of Cryptologic Research

In 1982, then-Deputy Director of the Central Intelligence Agency Bobby R. Inman wrote that

[a] ... source of tension arises when scientists, completely separate from the federal government, conduct research in areas where the federal government has an obvious and preeminent role for society as a whole. One example is the design of advanced weapons, especially nuclear ones. Another is cryptography. While nuclear weapons and cryptography are heavily dependent on theoretical mathematics, there is no public business market for nuclear weapons. Such a market, however, does exist for cryptographic concepts and gear to protect certain types of business communications.

[However], ... cryptologic research in the business and academic arenas, no matter how useful, remains redundant to the necessary efforts of the federal government to protect its own communications. I still am concerned that indiscriminate publication of the results of that research will come to the attention of foreign governments and entities and, thereby, could cause irreversible and unnecessary harm to U.S. national security interests.... [While] key features of science—unfettered research, and the publication of the results for validation by others and for use by all mankind—are essential to the growth and development of science, . . . nowhere in the scientific ethos is there any requirement that restrictions cannot or should not, when necessary, be placed on science. Scientists do not immunize themselves from social responsibility simply because they are engaged in a scientific pursuit. Society has recognized over time that certain kinds of scientific inquiry can endanger society as a whole and has applied either directly, or through scientific/ethical constraints, restrictions on the kind and amount of research that can be done in those areas.

For the original text of Inman's article, see "Classifying Science: A Government Proposal ... ," Aviation Week and Space Technology, February 8, 1982.

Adding to these concerns are suggestions such as those made by a responsible and senior government official that even research in cryptography conducted in the civilian sector should be controlled in a legal regime similar to that which governs research with relevance to nuclear weapons design (Box 7.3). Ironically, former NSA Director Bobby Inman's comments on scientific research appeared in an article that called for greater cooperation between academic scientists and national security authorities and used as a model of cooperation an arrangement, recommended by the Public Cryptography Study. Group, that has worked generally well in balancing the needs of academic science and those of na-

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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tional security.18Nevertheless, Inman's words are often cited as reflecting a national security mind-set that could lead to a serious loss of intellectual freedom and discourse. More recently, FBI Director Louis Freeh stated to the committee that "other approaches may be necessary" if technology vendors do not adopt escrowed encryption on their own. Moreover, the current Administration has explicitly rejected the premise that "every American, as a matter of right, is entitled to an unbreakable encryption product."19

Given concerns about possible compromises of personal and civil liberties, many skeptics of government in this area believe that the safest approach is for government to stay out of cryptography policy entirely. They argue that any steps in this area, no matter how well intentioned or plausible or reasonable, must be resisted strongly, because such steps will inevitably be the first poking of the camel's nose under the tent.

Technical Issues

Even if a legislative prohibition on the use of unescrowed encryption were enacted, it would be technically easy for parties with special needs for security to circumvent such a ban. In some cases, circumvention would be explicitly illegal, while in others it might well be entirely legal. For example:

• Software for unescrowed encryption can be downloaded from the Internet; such software is available even today. Even if posting such software in the United States were to be illegal under a prohibition, it would nonetheless be impossible to prevent U.S. Internet users from downloading software that had been posted on sites abroad.

18 The arrangement recommended by the Public Cryptography Study Group called for voluntary prepublication review of all cryptography research undertaken in the private sector. For more discussion of this arrangement, see Public Cryptography Study Group, Report of the Public Cryptography Study Group, American Council on Education, Washington, D.C., February, 1981. A history leading to the formation of the Public Cryptography Study Group can be found in National Research Council, "Voluntary Restraints on Research with National Security Implications: The Case of Cryptography, 1972-1982," in Scientific Communication and National Security, National Academy Press, Washington, D.C., 1982, Appendix E, pp. 120-125. The ACM study on cryptography policy concluded that this prepublication arrangement has not resulted in any chilling effects in the long term (see Susan Landau et al., Codes, Keys and Conflicts: Issues in U.S. Crypto Policy, Association for Computing Machinery Inc., New York, 1994, p. 39.)

19 "Questions and Answers About the Clinton Administration's Telecommunications Initiative," undated document released on April 16, 1993, with "Statement by the Press Secretary on the Clipper Chip." See The Third CPSR Cryptography and Privacy Conference Source Book, Computer Professionals for Social Responsibility, Washington, D.C., June 7, 1993, Part III.

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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• Superencryption can be used. Superencryption (sometimes also known as double encryption) is encryption of traffic before it is given to an escrowed encryption device or system. For technical reasons, superencryption is impossible to detect without monitoring and attempting to decrypt all escrow-encrypted traffic, and such large-scale monitoring would be seriously at odds with the selected and limited nature of wiretaps today.

An additional difficulty with superencryption is that it is not technically possible to obtain escrow information for all layers simultaneously, because the fact of double and triple encryption cannot be known in advance. Even if the second (or third or fourth) layers of encryption were escrowed, law enforcement authorities would have to approach separately and sequentially the escrow agents holding key information for those layers.

• Talent for hire is easy to obtain. A criminal party could easily hire a knowledgable person to develop needed software. For example, an outof-work or underemployed scientist or mathematician from the former Soviet Union would find a retainer fee of $500 per month to be a king's ransom.20

• Information can be stored remotely. An obvious noncryptographic circumvention is to store data on a remote computer whose Internet address is known only to the user. Such a computer could be physically located anywhere in the world (and might even automatically encrypt files that were stored there). But even if it were not encrypted, data stored on a remote computer would be impossible for law enforcement officials to access without the cooperation of the data's owner. Such remote storage could occur quite legally even with a ban on the use of unescrowed encryption.

• Demonstrating that a given communication or data file is ''encrypted" is fraught with ambiguities arising from the many different possibilities for sending information:

—An individual might use an obscure data format. For example, while ASCII is the most common representation of alphanumeric characters today, Unicode (a proposed 16-bit representation) and EBCDIC (a more-or-less obsolete 8-bit representation) are equally good for sending plain English text.

20 Alan Cooperman and Kyrill Belianinov, "Moonlighting by Modem in Russia," U.S. News & World Report, April 17, 1995, pp. 45-48. In addition, many high-technology jobs are moving overseas in general, not just to the former Soviet Union. See, for example, Keith Bradsher, "Skilled Workers Watch Their Jobs Migrate Overseas," New York Times, August 28, 1995, p. 1.

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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—An individual talking to another individual might speak in a language such as Navajo.

—An individual talking to another individual might speak in code phrases.

—An individual might send compressed digital data that could easily be confused with encrypted data despite having no purpose related to encryption. If, for example, an individual develops his own good compression algorithm and does not share it with anyone, that compressed bit stream may prove as difficult to decipher as an encrypted bit stream.21

—An individual might deposit fragments of a text or image that he wished to conceal or protect in a number of different Internet-accessible computers. The plaintext (i.e., the reassembled version) would be reassembled into a coherent whole only when downloaded into the computer of the user.22

—An individual might use steganography.23

None of these alternative coding schemes provides confidentiality as strong as would be provided by good cryptography, but their extensive use could well complicate attempts by government to obtain plaintext information.

Given so many different ways to subvert a ban on the use of unescrowed cryptography, emergence of a dedicated subculture is likely in which the nonconformists would use coding schemes or unescrowed cryptography impenetrable to all outsiders.

21 A discussion of using text compression for confidentiality purposes can be found in Ian Whitten and John Cleary, "On the Privacy Afforded by Adaptive Text Compression," Computers and Security, July 1988, Volume 7(4), pp. 397-408. One problem in using compression schemes as a technique for ensuring confidentiality is that almost any practical compression scheme has the characteristic that closely similar plaintexts would generate similar ciphertexts, thereby providing a cryptanalyst with a valuable advantage not available if a strong encryption algorithm is used.

22 Jaron Lanier, "Unmuzzling the Internet: How to Evade the Censors and Make a Statement, Too," Op-Ed, New York Times, January 2, 1996, p. A15.

23 Steganography is the name given to techniques for hiding a message within another message. For example, the first letter of each word in a sentence or a paragraph can be used to spell out a message, or a photograph can be constructed so as to conceal information. Specifically, most black-and-white pictures rendered in digital form use at most 216 (65,536) shades of gray, because the human eye is incapable of distinguishing any more shades. Each element of a digitized black-and-white photo would then be associated with 16 bits of information about what shade of gray should be used. If a picture were digitized with 24 bits of gray scale, the last 8 bits could be used to convey a concealed message that would never appear except for someone who knew to look for it. The digital size of the picture would be 50% larger than it would ordinarily be, but no one but the creator of the image would know.

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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Economic Concerns

An important economic issue that would arise with a legislative prohibition on the use of unescrowed cryptography would involve the political difficulty of mandating abandonment of existing user investments in products with encryption capabilities. These investments, considerable even today, are growing rapidly, and the expense to users of immediately having to replace unescrowed encryption products with escrowed ones could be enormous;24 a further expense would be the labor cost involved in decrypting existing encrypted archives and reencrypting them using escrowed encryption products. One potential mitigating factor for cost is the short product cycle of information technology products. Whether users would abandon nonconforming products in favor of new products with escrowing features—knowing that they were specifically designed to facilitate exceptional access—is open to question.

Legal and Constitutional Issues

Even apart from the issues described above, which in the committee's view are quite significant, a legislative ban on the domestic use of unescrowed encryption would raise constitutional issues. Insofar as a prohibition on unescrowed encryption were treated for constitutional purposes as a limitation on the content of communications, the government would have to come forward with a compelling state interest to justify the ban. To some, a prohibition on the use of unescrowed encryption would be the equivalent of a law proscribing use of a language (e.g., Spanish), which would almost certainly be unconstitutional. On the other hand, if such a ban were regarded as tantamount to eliminating a method of communication (i.e., were regarded as content-neutral), then the courts would employ a simple balancing test to determine its constitutionality. The government would have to show that the public interests were jeopardized by a world of unrestrained availability of encryption, and these interests would have to be weighed against the free speech interests sacrificed by the ban. It would also be significant to know what alternative

24 Existing unescrowed encryption products could be kept in place if end users could be made to comply with a prohibition on the use of such products. In some cases, a small technical fix might suffice to disable the cryptography features of a system; such fixes would be most relevant in a computing environment in which the software used by end users is centrally administered (as in the case of many corporations) and provides system administrators with the capability for turning off encryption. In other cases, users—typically individual users who had purchased their products from retail store outlets—would have to be trusted to refrain from using encryption.

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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forms of methods of anonymous communication would remain available with a ban and how freedom of speech would be affected by the specific system of escrow chosen by the government. These various considerations are difficult, and in some cases impossible, to estimate in advance of particular legislation and a particular case, but the First Amendment issues likely to arise with a total prohibition on the use of unescrowed encryption are not trivial.25

A step likely to raise fewer constitutional problems, but not eliminate them, is one that would impose restrictions on the commercial sale of unescrowed products with encryption capabilities.26 Under such a regime, products with encryption capabilities eligible for sale would have to conform to certain restrictions intended to ensure public safety, in much the same way that other products such as drugs, automobiles, and meat must satisfy particular government regulations. "Freeware" or homegrown products with encryption capabilities would be exempt from such regulations as long as they were used privately. The problem of already-deployed products would remain, but in a different form: new products would either interoperate or not interoperate with existing already-deployed products. If noninteroperability were required, users attempting to maintain and use two noninteroperating systems would be faced with enormous expenses. If interoperability were allowed, the intent of the ban would be thwarted.

Finally, any national policy whose stated purpose is to prevent the use of unescrowed encryption preempts decision making that the committee believes properly belongs to users. As noted in Chapter 5, escrowed encryption reduces the level of assured confidentiality in exchange for allowing controlled exceptional access to parties that may need to retrieve encrypted data. Only in a policy regime of voluntary compliance can users decide how to make that trade-off. A legislative prohibition on the use or sale of unescrowed encryption would be a clear statement that law enforcement needs for exceptional access to information clearly outweigh user interests in having maximum possible protection

25 For a view arguing that relevant Fourth and Fifth Amendment issues would be resolved against a constitutionality of such a prohibition, see Michael Froomkin, "The Metaphor Is the Key: Cryptography, The Clipper Chip and the Constitution," University of Pennsylvania Law Review, Volume 143(3), January 1995, pp. 709-897. The committee takes no position on these Fourth and Fifth Amendment issues.

26 Such a scheme has been suggested by Dorothy Denning in "The Future of Cryptography," Internet Security Monthly, October 1995, p. 10. (Also available on-line at http:// www.cosc.georgetown.edu/~denning/crypto.) Denning's paper does not suggest that "freeware" be exempt, although her proposal would provide an exemption for personally developed software used to encrypt personal files.

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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for their information, a position that has yet to be defended or even publicly argued by any player in the debate.

7.2.2 Criminalization of the Use of Cryptography in the Commission of a Crime

Proposals to criminalize the use of cryptography in the commission of a crime have the advantage that they focus the weight of the criminal justice system on the "bad guy" without placing restrictions on the use of cryptography by "good guys." Further, deliberate use of cryptography in the commission of a crime could result in considerable damage, either to society as a whole or to particular individuals, in circumstances suggesting premeditated wrongdoing, an act that society tends to view as worthy of greater punishment than a crime committed in the heat of the moment.

Two approaches could be taken to criminalize the use of cryptography in the commission of a crime:

• Construct a specific list of crimes in which the use of cryptography would subject the criminal to additional penalties. For example, using a deadly weapon in committing a robbery or causing the death of someone during the commission of a crime are themselves crimes that lead to additional penalties.

• Develop a blanket provision stating that the use of cryptography for illegal purposes (or for purposes contrary to law) is itself a felony.

In either event, additional penalties for the use of cryptography could be triggered by a conviction for a primary crime, or they could be imposed independently of such a conviction. Precedents include the laws criminalizing mail fraud (fraud is a crime, generally a state crime, but mail fraud—use of the mails to commit fraud—is an additional federal crime) and the use of a gun during the commission of a felony.

Intentional use of cryptography in the concealment of a crime could also be criminalized. Since the use of cryptography is a prima facie act of concealment, such an expansion would reduce the burden of proof on law enforcement officials, who would have to prove only that cryptography was used intentionally to conceal a crime. Providers of cryptography would be criminally liable only if they had knowingly provided cryptography for use in criminal activity. On the other hand, a law of more expansive scope might well impose additional burdens on businesses and raise civil liberties concerns.

In considering legal penalties for misuse of cryptography, the question of what it means to "use" cryptography must be addressed. For example, if and when encryption capabilities are integrated seamlessly into applications and are invoked automatically without effort on the part

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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of a user, should the use of these applications for criminal purposes lead to additional penalties or to a charge for an additional offense? Answering yes to this question provides another avenue for prosecuting a criminal (recall that Al Capone was convicted for income tax evasion rather than bank robbery).  Answering no leaves open the possibility of prosecutorial abuse. A second question is what counts as "cryptography." As noted above in the discussion of prohibiting unescrowed encryption, a number of mathematical coding schemes can serve to obscure the meaning of plaintext even if they are not encryption schemes in the technical sense of the word. These and related questions must be addressed in any serious consideration of the option for criminalizing the use of cryptography in the commission of a crime.

7.2.3 Technical Nonescrow Approaches for Obtaining Access to Information

Escrowed encryption is not the only means by which law enforcement can gain access to encrypted data. For example, as advised by Department of Justice guidelines for searching and seizing computers, law enforcement officials can approach the software vendor or the Justice Department computer crime laboratory for assistance in cryptanalyzing encrypted files. These guidelines also advise that "clues to the password [may be found] in the other evidence seized—stray notes on hardware or desks; scribble in the margins of manuals or on the jackets of disks. Agents should consider whether the suspect or someone else will provide the password if requested."27 Moreover, product designs intended to facilitate exceptional access can include alternatives with different strengths and weaknesses such as link encryption, weak encryption, hidden back doors, and translucent cryptography.

Link Encryption

With link encryption, which applies only to communications and stands in contrast to end-to-end encryption (Box 7.4), a plaintext message enters a communications link, is encrypted for transmission through the link, and is decrypted upon exiting the link. In a communication that may involve many links, sensitive information can be found in plaintext form at the ends of each link (but not during transit). Thus, for purposes of protecting sensitive information on an open network accessible to anyone (the Internet is a good example), link encryption is more vulnerable than

27 Criminal Division, U.S. Department of Justice, Federal Guidelines for Searching and Seizing Computers, Washington, D.C., July 1994, p. 55.

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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BOX 7.4
Link vs. End-to-End Encryption of Communications

End-to-end encryption involves a stream of data traffic (in one or both directions) that is encrypted by the end users involved before it is fed into the communications link; traffic in between the end users is never seen in plaintext, and the traffic is decrypted only upon receipt by an end user. Link encryption is encryption performed on data traffic after it leaves one of the end users; the traffic enters one end of the link, is encrypted and transmitted, and then is decrypted upon exit from that link.

TABLE 7.2 Comparison of End-to-End and Link Encryption

 

End-to-End Encryption

Link Encryption

Controlling party

User

Link provider

Suitable traffic

Most suitable for encryption of individual messages

Facilitates bulk encryption of data

Potential leaks of plaintext

Only at transmitting and receiving stations

At either end of the link, which may not be within the user's security perimeter

Point of responsibility

User must take responsibility

Link provider takes responsibility

end-to-end encryption, which protects sensitive information from the moment it leaves party A to the moment it arrives at party B. However, from the standpoint of law enforcement, link encryption facilitates legally authorized intercepts, because the traffic of interest can always be obtained from one of the nodes in which the traffic is unencrypted.

On a relatively closed network or one that is used to transmit data securely and without direct user action, link encryption may be costeffective and desirable. A good example would be encryption of the wireless radio link between a cellular telephone and its ground station; the cellular handset encrypts the voice signal and transmits it to the ground station, at which point it is decrypted and fed into the land-based network. Thus, the land-based network carries only unencrypted voice traffic, even though it was transmitted by an encrypted cellular telephone. A second example is the "bulk" encryption of multiple channels—each individually unencrypted—over a multiplexed fiber-optic link. In both of these instances of link encryption, only those with access to carrier facili-

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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ties—presumably law enforcement officials acting under proper legal authorization—would have the opportunity to tap such traffic.

Weak Encryption

Weak encryption allowing exceptional access would have to be strong enough to resist brute-force attack by unauthorized parties (e.g., business competitors) but weak enough to be cracked by authorized parties (e.g., law enforcement agencies). However, "weak" encryption is a moving target. The difference between cracking strong and weak encryption by brute-force attack is the level of computational resources that can be brought to such an attack, and those resources are ever increasing. In fact, the cost of brute-force attacks on cryptography drops exponentially over time, in accordance with Moore's law.28

Widely available technologies now enable multiple distributed workstations to work collectively on a computational problem at the behest of only a few people; Box 4.6 in Chapter 4 discusses the brute-force cryptanalysis of messages encrypted with the 40-bit RC4 algorithm, and it is not clear that the computational resources of unauthorized parties can be limited in any meaningful way. In today's environment, unauthorized parties will almost always be able to assemble the resources needed to mount successful brute-force attacks against weak cryptography, to the detriment of those using such cryptography. Thus, any technical dividing line between authorized and unauthorized decryption would change rather quickly.

Hidden Back Doors

A "back door" is an entry point to an application that permits access or use by other than the normal or usual means. Obviously, a back door known to government can be used to obtain exceptional access. Back doors may be open or hidden. An open back door is one whose existence is announced publicly; an example is an escrowed encryption system, which everyone knows is designed to allow exceptional access.29 By its

28 Moore's law is an empirical observation that the cost of computation drops by a factor of two approximately every 18 months.

29 Of course, the fact that a particular product is escrowed may not necessarily be known to any given user. Many users learn about the features of a product through reading advertisments and operating manuals for the product; if these printed materials do not mention the escrowing features, and no one tells the user, he or she may well remain ignorant of them, even though the fact of escrow is "public knowledge."

Suggested Citation:"Policy Options for the Future." National Research Council. 1996. Cryptography's Role in Securing the Information Society. Washington, DC: The National Academies Press. doi: 10.17226/5131.
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nature, an open back door is explicit; it must be deliberately and intentionally created by a designer or implementer.

A hidden back door is one whose existence is not widely known, at least upon initial deployment. It can be created deliberately (e.g., by a designer who insists on retaining access to a system that he may have created) or accidentally (e.g., as the result of a design flaw). Often, a user wishing access through a deliberately created hidden back door must pass through special system-provided authorization services. Almost by definition, an accidentally created hidden back door requires no special authorization for its exploitation, although finding it may require special knowledge. In either case, the existence of hidden back doors may or may not be documented; frequently, it is not.

Particularly harmful hidden back doors can appear when "secure" applications are implemented using insecure operating systems; more generally, "secure" applications layered on top of insecure systems may not be secure in practice. Cryptographic algorithms implemented on weak operating systems present another large class of back doors that can be used to undermine the integrity and the confidentiality that cryptographic implementations are intended to provide. For example, a database application that provides strong access control and requires authorization for access to its data files but is implemented on an operating system that allows users to view those files without going through the database application does not provide strong confidentiality. Such an application may well have its data files encrypted for confidentiality.

The existence of back doors can pose high-level risks. The shutdown or malfunction of life-critical systems, loss of financial stability in electronic commerce, and compromise of private information in database systems can all have serious consequences. Even if back doors are undocumented, they can be discovered and misused by insiders or outsiders. Reliance on "security by obscurity" is always dangerous, because trying to suppress knowledge of a design fault is generally very difficult. If a back door exists, it will eventually be discovered, and its discoverer can post that knowledge worldwide. If systems containing a discovered back door were on the Internet or were accessible by modem, massive exploitation could occur almost instantaneously, worldwide. If back doors lack a capability for adequate authentication and accountability, then it can be very difficult to detect exploitation and to identify the culprit.

Translucent Cryptography

Translucent cryptography has been proposed by Ronald Rivest as an

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alternative to escrowed encryption.30 The proposed technical scheme, which involves no escrow of unit keys, would ensure that any given message or file could be decrypted by the government with probability p; the value of p (0 < p < 1) would be determined by the U.S. Congress. In other words, on average, the government would be able to decrypt a fraction p of all messages or files to which it was given legal access. Today (without encryption), p = 1. In a world of strong (unescrowed) encryption, p = 0. A large value of p favors law enforcement, while a small value of p favors libertarian privacy. Rivest proposes that some value of p balances the interests on both sides.

It is not necessary that the value of p be fixed for all time or be made uniform for all devices. p could be set differently for cellular telephones and for e-mail, or it could be raised or lowered as circumstances dictated. The value of p would be built into any given encryption device or program.

Note that in contrast to escrowed encryption, translucent cryptography requires no permanent escrowing of unit keys, although it renders access indeterminate and probabilistic.

7.2.4 Network-based Encryption
Security for Voice Communications

In principle, secure telephony can be made the responsibility of telephone service providers. Under the current regulatory regime (changing even as this report is being written), tariffs often distinguish between data and voice. Circuits designated as carrying ordinary voice (also to include fax and modem traffic) could be protected by encryption supplied by the service provider, perhaps as an extra security option that users could purchase. Common carriers (service providers in this context) that provide encryption services are required by the Communications Assistance for Law Enforcement Act to decrypt for law enforcement authorities upon legal request. (The "trusted third party" (TTP) concept discussed in Europe31 is similar in the sense that TTPs are responsible for providing key management services for secure communications. In particular, TTPs provide session keys over secure channels to end users that they can then

30 Ronald Rivest, "Translucent Cryptography: An Alternative to Key Escrow," paper presented at the Crypto 1995 Rump Session, August 29, 1995.

31 See, for example, Nigel Jefferies, Chris Mitchell, and Michael Walker, A Proposed Architecture for Trusted Third Party Services, Royal Holloway, University of London, 1995.

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use to encrypt communications with parties of interest; these keys are made available to law enforcement officials upon authorized request.)

The simplest version of network-based encryption would provide for link encryption (e.g., encrypting the voice traffic only between switches). Link encryption would leave the user vulnerable to eavesdropping at a point between the end-user device and the first switching office. In principle, a secure end-user device could be used to secure this ''last mile" link.32

Whether telecommunications service providers will move ahead on their own with network-based encryption for voice traffic is uncertain for a number of reasons. Because most people today either believe that their calls are reasonably secure or are not particularly concerned about the security of their calls, the extent of demand for such a service within the United States is highly uncertain. Furthermore, by moving ahead in a public manner with voice encryption, telephone companies would be admitting that calls carried on their network are today not as secure as they could be; such an acknowledgment might undermine their other business interests. Finally, making network-based encryption work internationally would remain a problem, although any scheme for ensuring secure international communications will have drawbacks.

More narrowly focused network-based encryption could be used with that part of the network traffic that is widely acknowledged to be vulnerable to interception—namely, wireless voice communications. Wireless communications can be tapped "in the ether" on an entirely passive basis, without the knowledge of either the sending or receiving party. Of particular interest is the cellular telephone network; all of the current standards make some provisions for encryption. Encryption of the wireless link is also provided by the Global System for Mobile Communications (GSM), a European standard for mobile communications. In general, communication is encrypted from the mobile handset to the cell, but not end to end. Structured in this manner, encryption would not block the ability of law enforcement to obtain the contents of a call, because access could always be obtained by tapping the ground station.

At present, transmission of most wireless communications is analog. Unless special measures are taken to prevent surveillance, analog transmissions are relatively easy to intercept. However, it is widely expected

32 The "last mile" is a term describing that part of a local telephone network between the premises of an individual subscriber and the central-office switch from which service is received. The vulnerability of the "last mile" is increased because it is easier to obtain access to the physical connections and because the volume of traffic is small enough to permit the relevant traffic to be isolated easily. On the other hand, the vulnerability of the switch is increased because it is often accessible remotely through dial-in ports.

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that wireless communications will become increasingly digital in the future, with two salutary benefits for security. One is that compared to analog signals, even unencrypted digital communications are difficult for the casual eavesdropper to decipher or interpret, simply because they are transmitted in digital form. The second is that digital communications are relatively easy to encrypt.

Security for Data Communications

The body responsible for determining technical standards for Internet communications, the Internet Engineering Task Force, has developed standards for the Internet Protocol (version 6, also known as IPv6) that require conforming implementations to have the ability to encrypt data packets, with the default method of encryption being DES.33 However, IPv6 standards are silent with respect to key management, and so leave open the possibility that escrow features might or might not be included at the vendor's option.

If the proposed standards are finalized, vendors may well face a Hobson's choice: to export Internet routing products that do not conform to the IPv6 standard (to obtain favorable treatment under the current ITAR, which do not allow exceptions for encryption stronger than 40-bit with RC2 or RC4), or to develop products that are fully compliant with IPv6 (a strong selling point), but only for the domestic market. Still,

33 The Network Working Group has described protocols that define standards for encryption, authentication, and integrity in the Internet Protocol. These protocols are described in the following documents, issued by the Network Working Group as Requests for Comments (RFCs) in August 1995:
RFC     Title
1825    Security Architecture for the Internet Protocol (IP); describes the security mechanisms for IP version 4 (IPv4) and IP version 6 (IPv6).
1826    IP Authentication Header (AH); describes a mechanism for providing cryptographic authentication for IPv4 and IPv6 datagrams.
1827    IP Encapsulating Security Payload (ESP); describes a mechanism that works in both IPv4 and IPv6 for providing integrity and confidentiality to IP datagrams.
1828    IP Authentication using Keyed MD5; describes the use of a particular authentication technique with IP-AH.
1829    The ESP DES-CBC Transform; describes the use of a particular encryption technique with the IP Encapsulating Security Payload.
These documents are available from ftp://ds.internic.net/rfc/rfcNNNN.txt, where NNNN is the RFC number.

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escrowed implementations of IPv6 would be consistent with the proposed standard and might be granted commodities jurisdiction to the Commerce Control List under regulations proposed by the Administration for escrowed encryption products.

7.2.5 Distinguishing Between Encrypted Voice and Data Communications Services for Exceptional Access

For purposes of allowing exceptional access, it may be possible to distinguish between encrypted voice and data communications, at least in the short run. Specifically, a proposal by the JASON study group suggests that efforts to install features for exceptional access should focus on secure voice communications, while leaving to market forces the evolution of secure data communications and storage.34 This proposal rests on the following propositions:

• Telephony, as it is experienced by the end user, is a relatively mature and stable technology, compared to data communications services that evolve much more rapidly. Many people—perhaps the majority of the population—will continue to use devices that closely resemble the telephones of today, and many more people are familiar with telephones than are familiar with computers or the Internet.

• An important corollary is that regulation of rapidly changing technologies is fraught with more danger than is the regulation of mature technologies, simply because regulatory regimes are inherently slow to react and may well pose significant barriers to the development of new technologies. This is especially true in a field moving as rapidly as information technology.

• Telephony has a long-standing regulatory and technical infrastructure associated with it, backed by considerable historical precedent, such as that for law enforcement officials obtaining wiretaps on telephonic communications under court order. By contrast, data communications services are comparatively unregulated (Box 7.5).

• In remarks to the committee, FBI Director Louis Freeh pointed out that it was voice communications that drove the FBI's desire for passage of the Communications Assistance for Law Enforcement Act (CALEA); he acknowledged that other mechanisms for communication might be relevant to law enforcement investigations but has undertaken nonlegislative approaches to deal with those mechanisms.

34 JASON Program Office, JASON Encryption/Privacy Study, Report JSR-93-520 (unpublished), MITRE Corporation, McLean, Va., 1993.

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BOX 7.5
Two Primary Rate and Service Models for Telecommunications Today

Regulated Common Carrier Telephony Services

Regulated common carrier telephony services are usually associated with voice telephony, including fax and low-speed modem data communications. If a "common carrier" provision applies to a given service provider, the provider must provide service to anyone who asks at a rate that is determined by a public utilities commission. Common carriers often own their own transport facilities (e.g., fiber-optic cables, telephone wires, and so on), and thus the service provider exerts considerable control over the routing of a particular communication. Pricing of service for the end user is often determined on the basis of actual usage. The carrier also provides value-added services (e.g., call waiting) to enhance the value of the basic service to the customer. Administratively, the carrier is usually highly centralized.

Bulk Data Transport

Bulk services are usually associated with data transport (e.g., data sent from one computer to another) or with "private" telephony (e.g., a privately owned or operated branch exchange for telephone service within a company). Pricing for bulk services is usually a matter of negotiation between provider and customer and may be based on statistical usage, actual usage, reliability of transport, regional coverage, or other considerations. Policy for use is set by the party that pays for the bulk service, and thus, taken over the multitude of organizations that use bulk services, is administratively decentralized. In general, the customer provides value-added services. Routing paths are often not known in advance, but instead may be determined dynamically.

• Demand for secure telephone communications, at least domestically, is relatively small, if only because most users consider today's telephone system to be relatively secure. A similar perception of Internet security does not obtain today, and thus the demand for highly secure data communications is likely to be relatively greater and should not be the subject of government interference.

Under the JASON proposal, attempts to influence the inclusion of escrow features could affect only the hardware devices that characterize telephony today (e.g., a dedicated fax device, an ordinary telephone). In general, these devices do now allow user programming or additions and, in particular, lack the capability enabling the user to provide encryption easily.

The JASON study also recognized that technical trends in telecommunications are such that telephony will be increasingly indistinguish-

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able from data communications. One reason is that communications are becoming increasingly digital. A bit is a bit, whether it was originally part of a voice communication or part of a data communication, and the purpose of a communications infrastructure is to transport bits from Point A to Point B, regardless of the underlying information content; reconstituting the transported bits into their original form will be a task left to the parties at Point A and Point B. Increasingly, digitized signals for voice, data, images, and video will be transported in similar ways over the same network facilities, and often they will be combined into single multiplexed streams of bits as they are carried along.35

For example, a voice-generated analog sound wave that enters a telephone may be transmitted to a central switching office, at which point it generally is converted into a digital bit stream and merged with other digital traffic that may originally have been voices, television signals, and high-speed streams of data from a computer. The network transports all of this traffic across the country by a fiber-optic cable and converts the bits representing voice back into an analog signal only when it reaches the switching office that serves the telephone of the called party. To a contemporary user of the telephone, the conversation proceeds just as it might have done 30 years ago (although probably with greater fidelity), but the technology used to handle the call is entirely different.

Alternatively, a computer connected to a data network can be converted into the functional equivalent of a telephone.36 Some on-line service providers will be offering voice communications capability in the near future, and the Internet itself can be used today to transport realtime voice and even video communications, albeit with relatively low fidelity and reliability but also at very low cost.37 Before these modalities

35 Note, however, that the difficulty of searching for a given piece of information does depend on whether it is voice or text. It is quite straightforward to search a given digital stream for a sequence of bits that represents a particular word as text, but quite difficult to search a digital stream for a sequence of bits that represents that particular word as voice.

36 For example, an IBM catalogue offers for general purchase a "DSP Modem and Audio Card" with "Telephony Enhancement" that provides a full-duplex speaker telephone for $254. The card is advertised as being able to make the purchaser's PC into "a telephone communications center with telephone voice mail, caller ID, and full duplex speakerphone capability (for true simultaneous, two-way communications)." See The IBMPC Direct Source Book, Fall 1994, p. 43. An article in the Hewlett-Packard Journal describes the ease with which a telephone option card was developed for a workstation; see S. Paul Tucker, "HP TeleShare: Integrating Telephone Capabilities on a Computer Workstation," Hewlett-Packard Journal, April 1995, pp. 69-74.

37 In January 1996, it was estimated that approximately 20,000 people worldwide are users of Internet telephone service. See Mike Mills, "It's the Net's Best Thing to Being There," Washington Post, January 23, 1996, p. C1.

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become acceptable for mainstream purposes, the Internet (or its successor) will have to implement on a wide scale new protocols and switching services to eliminate current constraints that involve time delays and bandwidth limitations.

A second influence that will blur the distinction between voice and data is that the owners of the devices and lines that transport bits today are typically the common carriers—firms originally formed to carry long-distance telephone calls and today subject to all of the legal requirements imposed on common carriers (see Box 7.5). But these firms sell transport capacity to parties connecting data networks, and much of today's bulk data traffic is carried over communications links that are owned by the common carriers. The Telecommunications Reform Act of 1996 will further blur the lines among service providers.

The lack of a technical boundary between telephony and data communications results from the way today's networks are constructed. Networks are built on a protocol "stack" that embodies protocols at different layers of abstraction. At the very bottom are the protocols for the physical layer that define the voltages and other physical parameters that represent ones and zeros. On top of the physical layer are other protocols that provide higher-level services by making use of the physical layer. Because the bulk of network traffic is carried over a physical infrastructure designed for voice communications (i.e., the public switched telecommunications network), interactions at the physical layer can be quite naturally regarded as being in the domain of "voice." But interactions at higher layers in the stack are more commonly associated with "data."

Acknowledging these difficulties, the JASON study concluded that limiting efforts to promote escrowed encryption products to those associated with voice communications had two important virtues. First, it would help to preserve law enforcement needs for access to a communications mode—namely telephony—that is widely regarded as important to law enforcement. Second, it would avoid premature government regulation in the data services area (an area that is less important historically to criminal investigation and prosecution than is telephony), thus avoiding the damage that could be done to a strong and rapidly evolving U.S. information technology industry. It would take—several years to a decade—for the technical "loopholes" described above to become significant, thus giving law enforcement time to adapt to a new technical reality.

7.2.6 A Centralized Decryption Facility for Government Exceptional Access

Proposed procedures to implement the retrieval of keys escrowed under the Clipper initiative call for the escrowed key to be released by the

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escrow agencies to the requesting law enforcement authorities upon presentation of proper legal authorization, such as a court order. Critics have objected to this arrangement because it potentially compromises keys for all time—that is, once the key to a specific telephone has been divulged, it is in principle possible to eavesdrop forever on conversations using that telephone, despite the fact that court-ordered wiretaps must have a finite duration.

To counter this criticism, Administration officials have designed a plan that calls for keys to be transmitted electronically to EES decryption devices in such a way that the decryption device will erase the key at the time specified in the court order. However, acceptance of this plan relies on assurances that the decryption device would indeed work in this manner. In addition, this proposal is relevant only to the final plan—the interim procedures specify manual key handling.

Another way to counter the objection to potential long-lasting compromise of keys involves the use of a centralized government-operated decryption facility. Such a facility would receive EES-encrypted traffic forwarded by law enforcement authorities and accompanied by appropriate legal authorization. Keys would be made available by the escrow agents to the facility rather than to the law enforcement authorities themselves, and the plaintext would be returned to the requesting authorities. Thus, keys could never be kept in the hands of the requesting authorities, and concern about illicit retention of keys by law enforcement authorities could be reduced. Of course, concerns about retention by the decryption facility would remain, but since the number of decryption facilities would be small compared to the number of possible requesting law enforcement authorities, the problem would be more manageable. Since the decryption facilities would likely be under centralized control as well, it would be easier to promulgate and enforce policies intended to prevent abuse.38

38 The committee suspects that the likelihood of abusive exercise of wiretap authority is greater for parties that are farther removed from higher levels of government, although the consequences may well be more severe when parties closer to the top levels of government are involved. A single "bad apple" near the top of government can set a corrupt and abusive tone for an entire government, but at least "bad apples" tend to be politically accountable. By contrast, the number of parties tends to increase as those parties are farther and farther removed from the top, and the likelihood that at least some of these parties will be abusive seems higher. (Put differently, the committee believes that state/local authorities are more likely to be abusive in their exercise of wiretapping authority simply because they do the majority of the wiretaps. Note that while Title III calls for a report to be filed on every federal and state wiretap order, the majority of missing reports are mostly from state wiretap orders rather than federal orders. (See Administrative Office of the United States Courts, Wiretap Report, AOUSC, Washington, D.C., April 1995, Table 2.)

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One important aspect of this proposal is that the particular number of facilities constructed and the capacity of each could limit the number of simultaneous wiretaps possible at any given time. Such a constraint would force law enforcement authorities to exercise great care in choosing targets for interception, just as they must when they are faced with constraints on resources in prosecuting cases. A result could be greater public confidence that only wiretaps were being used only in important cases. On the other hand, a limit on the number of simultaneous wiretaps possible is also a potential disadvantage from the standpoint of the law enforcement official, who may not wish to make resource-driven choices about how and whom to prosecute or investigate. Making encryption keys directly available to law enforcement authorities allows them to conduct wiretaps unconstrained by financial and personnel limitations.

A centralized decryption facility would also present problems of its own. For example, many people would regard it as more threatening to give a centralized entity the capability to acquire and decrypt all traffic than to have such capabilities distributed among local law enforcement agencies. In addition, centralizing all wiretaps and getting the communications out into the field in real time could require a complex infrastructure. The failure of a centralized facility would have more far-reaching effects than a local failure, crippling a much larger number of wiretaps at once.

7.3 LOOMING ISSUES

Two looming issues have direct significance for national cryptography policy: determining the level of encryption needed to protect against high-quality attacks, and organizing the U.S. government for a society that will need better information security. Appendix M describes two other issues that relate but are not central to the current debate over cryptography policy: digital cash and the use of cryptography to protect intellectual property.

7.3.1 The Adequacy of Various Levels of Encryption Against High-Quality Attack

What level of encryption strength is needed to protect information against high-quality attack? For purposes of analysis, this discussion considers only perfect implementations of cryptography for confidentiality (i.e., implementations without hidden "trap doors," installed on secure operating systems, and so on). Thus, the only issue of significance for this discussion is the size of the key and the algorithm used to encrypt the original plaintext.

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Any cryptanalysis problem can be solved by brute force given enough computers and time; the question is whether it is possible to assemble enough computational resources to allow a brute-force cryptanalysis on a time scale and cost reasonable for practical purposes.

As noted in Chapter 4, a message encoded with a 40-bit RC4 algorithm was recently broken in 8 days by a brute-force search through the use of a single workstation optimized for speed in graphics processing.

Even so, such a key size is adequate for many purposes (e.g., credit card purchases). It is also sufficient to deny access to parties with few technical skills, or to those with access to limited computing resources. But if the data being protected is valuable (e.g., if it refers to critical proprietary information), 40-bit keys are inadequate from an information security perspective. The reason is that for logistical and administrative reasons, it does not make sense to require a user to decide what information is or is not critical—the simplest approach is to protect both critical and noncritical information alike at the level required for protecting critical information. If this approach is adopted, the user does not run the risk of inadequately protecting sensitive information. Furthermore, the compromise of a single piece of information can be catastrophic, and since it is generally impossible to know if a particular piece of information has been compromised, those with a high degree of concern for the confidentiality of information must be concerned about protecting all information at a level higher than the thresholds offered by the 8-day cryptanalysis time described above.

From an interceptor's point of view, the cryptanalysis times provided by such demonstrations are quite daunting, because they refer to the time needed to cryptanalyze a single message. A specific encrypted message cryptanalyzed in this time may be useful when it is known with high probability to be useful; however, such times are highly burdensome when many messages must be collected and processed to yield one useful message. An eavesdropper could well have considerable difficulty in finding the ciphertext corresponding to critical information, but the information security manager cannot take the chance that a critical piece of information might be compromised anyway.39

A larger key size increases the difficulty of a brute-force search. For

39 In general, information security managers must develop a model of the threat and respond to that threat, rather than simply assuming the worst (for which the only possible response would be to do "everything"). However, in the case of encryption and in the absence of governmental controls on technology, strong encryption costs about the same as weak encryption. Under such circumstances, it makes no sense at all for the information security manager to choose weak encryption.

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symmetric algorithms, a 56-bit key entails a work factor that is 216 (65,536) times larger than that of a 40-bit key, and implies a search time of about 1,430 years to accomplish (assuming that the algorithm using that key would take about the same time to execute as the RC4 algorithm). Using more computers could decrease the time proportionally. (A discussion of key lengths for asymmetric algorithms is contained in Chapter 2.)

Large speed-up factors for search time would be possible through the use of special-purpose hardware, which can be optimized to perform specific tasks. Estimates have been made regarding the amount of money and time needed to conduct an exhaustive key search against a message encrypted using the DES algorithm. Recent work by Wiener in 1993,40 Dally in 1994,41 and Diffie et al. in 199642 suggest the feasibility of using special-purpose processors costing a few million dollars working in parallel or in a distributed fashion to enable a brute-force solution of a single 56-bit DES cipher on a time scale of hours. When the costs of design, operation, and maintenance are included (and these costs are generally much larger than the cost of the hardware itself), the economic burden of building and using such a machine would be significant for most individuals and organizations. Criminal organizations would have to support an infrastructure for cracking DES through brute-force search clandestinely, to avoid being targeted and infiltrated by law enforcement officials. As a result, developing and sustaining such an infrastructure would be even more difficult for criminals attempting to take that approach.

Such estimates suggest that brute-force attack against 56-bit algorithms such as DES would require the significant effort of a well-funded adversary with access to considerable resources. Such attacks would be far more likely from foreign intelligence services or organized criminal cartels with access to considerable resources and expertise, for whom the plaintext information sought would have considerable value, than from the casual snoop or hacker who is merely curious or nosy.

Thus, for routine information of relatively low or moderate sensitivity or value, 56-bit protection probably suffices at this time. But for information of high value, especially information that would be valuable to

40 M.J. Wiener, "Efficient DES Key Search," TR-244, May 1994, School of Computer Science, Carleton University, Ottawa, Canada; presented at the Rump Session of Crypto '93.

41 William P. Dally, Professor of Electrical Engineering, Massachusetts Institute of Technology, private communication to the committee, September 1995.

42 Matt Blaze, Whitfield Diffie, Ronald L. Rivest, Bruce Schneier, Tsutomu Shimomura, Eric Thompson, and Michael Wiener, "Minimal Key Lengths for Symmetric Ciphers to Provide Adequate Commercial Security: A Report by an Ad Hoc Group of Cryptographers and Computer Scientists," January 1996. Available on-line at http://www.bsa.org.

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foreign intelligence services or major competitors, the adequacy in a decade of 56-bit encryption against a determined and rich attacker is open to question.

7.3.2 Organizing the U.S. Government for Better Information Security on a National Basis

As noted in Chapter 6, no organization or entity within the federal government has the responsibility for promoting information security in the private sector or for coordinating information security efforts between government and nongovernment parties. NIST is responsible for setting Federal Information Processing Standards, and from time to time the private sector adopts these standards, but NIST has authority for information security only in unclassified government information systems. Given the growing importance of the private nongovernment sector technologically and the dependence of government on the private information infrastructure, security practices of the private information infrastructure may have a profound effect on government activities, both civilian and military.

How can coordination be pursued? Coherent policy regarding information assurance, information security, and the operation of the information infrastructure itself is needed. Business interests and the private sector need to be represented at the policy-making table, and a forum for resolving policy issues is needed. And, since the details of implementation are often critical to the success of any given policy, policy implementation and policy formulation must go hand in hand.

Information security functions that may call for coordinated national action vary in scale from large to small:

• Assisting individual companies in key commercial sectors at their own request to secure their corporate information infrastructures by providing advice, techniques, and analysis that can be adopted at the judgment and discretion of the company involved. In some key sectors (e.g., banking and telecommunications), conduits and connections for such assistance already exist as the result of government regulation of firms in those sectors. At present, the U.S. government will provide advice regarding information security threats, vulnerabilities, and solutions only to government contractors (and federal agencies).43

• Educating users both inside and outside government about vari-

43 This responsibility belongs to the NSA, as specified in the NSA-NIST Memorandum of Understanding of March 24, 1989 (reprinted in Office of Technology Assessment, Information Security and Privacy in Network Environments, OTA-TCT-606, U.S. Government Printing Office, Washington, D.C., September 1994, and in Appendix N).

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ous aspects of better information security. For example, many product vendors and potential users are unaware of the fact that there are no legal barriers to the use of cryptography domestically. Outreach efforts could also help in publicizing the information security threat.

• Certifying appropriate entities that perform some cryptographic service. For example, a public-key infrastructure for authentication requires trusted certification authorities (Appendix H). Validating the bona fides of these authorities (e.g., through a licensing procedure) will be an essential aspect of such an infrastructure. In the event that private escrow agents become part of an infrastructure for the wide use of cryptography, such agents will need to be approved or certified to give the public confidence in using them.

• Setting de jure standards for information security. As noted above, the NIST charter prevents it from giving much weight to commercial or private sector needs in the formulation of Federal Information Processing Standards if those needs conflict with those of the federal government, even when such standards affect practice in the private sector. Standards of technology and of practice that guide the private sector should be based on private sector needs, both to promote ''best practices" for information security and to provide a legitimate defense in liability cases involving breaches of information security.

How such functions should be implemented is another major question. The committee does not wish to suggest that the creation of a new organization is the only possible mechanism for performing these functions; some existing organization or entity could well be retooled to service these purposes. But it is clear that whatever entity assumes these functions must be highly insulated from political pressure (arguing for a high degree of independence from the executive branch), broadly representative (arguing for the involvement of individuals who have genuine policy-making authority drawn from a broad range of constituencies, not just government), and fully capable of hearing and evaluating classified arguments if necessary (arguing the need for security clearances).44

One proposal that has been discussed for assuming these responsibilities is based on the Federal Reserve Board. The Federal Reserve Board oversees the Federal Reserve System (FRS), the nation's central bank. The

44 As noted in the preface to this report, the committee concluded that the broad outlines of national cryptography policy can be argued on an unclassified basis. Nevertheless, it is a reality of decision making in the U.S. government on these matters that classified information may nevertheless be invoked in such discussions and uncleared participants asked to leave the room. To preclude this possibility, participating members should have the clearances necessary to engage as full participants in order to promote an effective interchange of views and perspectives.

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FRS is responsible for setting monetary policy (e.g., setting the discount rate), the supervision of banking organizations and open market operations, and providing services to financial institutions. The Board of Governors is the FRS's central coordinating body. Its seven members are appointed by the President of the United States and confirmed by the Senate for 14-year terms. These terms are staggered to insulate the governors from day-to-day political pressure. Its primary function is the formulation of monetary policy, but the Board of Governors also has supervisory and regulatory responsibilities over the activities of banking organizations and the Federal Reserve Banks.

A second proposal has been made by the Cross-Industry Working Team (XIWT) of the Corporation for National Research Initiatives for the U.S. government to establish a new Joint Security Technology Policy Board as an independent agency of the government.45 Under this proposal, the board would be an authoritative agency and coordination body officially chartered by statute or executive order "responsible and answerable" for federal performance across all of its agencies, and for promotion of secure information technology environments for the public. In addition, the board would solicit input, analysis, and recommendations about security technology policy concerns from private sector groups and government agencies, represent these groups and agencies within the board, disseminate requests and inquiries and information back to these groups and agencies, review draft legislation in cognizant areas and make recommendations about the legislation, and represent the U.S. government in international forums and other activities in the domain of international security technology policy. The board would be chaired by the Vice President of the United States and would include an equal number of members appointed from the private sector and the federal government.

A third proposal, perhaps more in keeping with the objective of minimal government, could be to utilize existing agencies and organizational structures. The key element of the proposal would be to create an explicit function in the government, that of domestic information security. Because information policy intersects with the interests and responsibilities of several agencies and cabinet departments, the policy role should arguably reside in the Executive Office of the President. Placing the policy function there would also give it the importance and visibility it requires. It might also be desirable to give specific responsibility for the initiation and coordination of policy to a Counselor to the President for Domestic Informa-

45 Cross-Industry Working Team, A Process for Information Security Technology: An XIWT Report on Industry-Government Cooperation for Effective Public Policy, March 1995. Available from Corporation for National Research Initiatives, Reston, Va., or on-line at http:// www.cnri.reston.va.us.

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tion Security (DIS). This individual could chair an interagency committee consisting of agencies and departments with a direct interest in and responsibilities for information security matters, including the operating agency, economic policy agencies (Departments of Treasury and Commerce), law enforcement agencies (FBI; Drug Enforcement Administration; Bureau of Alcohol, Tobaccco, and Firearms), and international affairs and intelligence agencies (Departments of State and Defense, CIA).

Operationally, a single agency could have responsibility for standards setting, certification of escrow agents, approval of certificate holders for authentication purposes, public education on information security, definition of "best practices," management of cryptography on the Commerce Control List, and so on. The operating agency could be one with an economic policy orientation, such as the Department of Commerce. An alternative point of responsibility might be the Treasury Department, although its law enforcement responsibilities could detract from the objective of raising the economic policy profile of the information security function.

The public advisory committee, which is an essential element of this structure, could be made up of representatives of the computing, telecommunications, and banking industries, as well as "public" members from academia, law, and so on. This committee could be organized along the lines of the President's Foreign Intelligence Advisory Board and could report to the Counselor for DIS.

7.4 RECAP

This chapter describes a number of possible policy options but does not attempt to pull together how these options might fit together in a coherent policy framework. That is the function of Chapter 8.

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For every opportunity presented by the information age, there is an opening to invade the privacy and threaten the security of the nation, U.S. businesses, and citizens in their private lives. The more information that is transmitted in computer-readable form, the more vulnerable we become to automated spying. It's been estimated that some 10 billion words of computer-readable data can be searched for as little as $1. Rival companies can glean proprietary secrets . . . anti-U.S. terrorists can research targets . . . network hackers can do anything from charging purchases on someone else's credit card to accessing military installations. With patience and persistence, numerous pieces of data can be assembled into a revealing mosaic. Cryptography's Role in Securing the Information Society addresses the urgent need for a strong national policy on cryptography that promotes and encourages the widespread use of this powerful tool for protecting of the information interests of individuals, businesses, and the nation as a whole, while respecting legitimate national needs of law enforcement and intelligence for national security and foreign policy purposes. This book presents a comprehensive examination of cryptography--the representation of messages in code--and its transformation from a national security tool to a key component of the global information superhighway. The committee enlarges the scope of policy options and offers specific conclusions and recommendations for decision makers. Cryptography's Role in Securing the Information Society explores how all of us are affected by information security issues: private companies and businesses; law enforcement and other agencies; people in their private lives. This volume takes a realistic look at what cryptography can and cannot do and how its development has been shaped by the forces of supply and demand. How can a business ensure that employees use encryption to protect proprietary data but not to conceal illegal actions? Is encryption of voice traffic a serious threat to legitimate law enforcement wiretaps? What is the systemic threat to the nation's information infrastructure? These and other thought-provoking questions are explored. Cryptography's Role in Securing the Information Society provides a detailed review of the Escrowed Encryption Standard (known informally as the Clipper chip proposal), a federal cryptography standard for telephony promulgated in 1994 that raised nationwide controversy over its "Big Brother" implications. The committee examines the strategy of export control over cryptography: although this tool has been used for years in support of national security, it is increasingly criticized by the vendors who are subject to federal export regulation. The book also examines other less well known but nevertheless critical issues in national cryptography policy such as digital telephony and the interplay between international and national issues. The themes of Cryptography's Role in Securing the Information Society are illustrated throughout with many examples -- some alarming and all instructive -- from the worlds of government and business as well as the international network of hackers. This book will be of critical importance to everyone concerned about electronic security: policymakers, regulators, attorneys, security officials, law enforcement agents, business leaders, information managers, program developers, privacy advocates, and Internet users.

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