This bulletin discusses when and how FIPS 140-1 should be used and examines the benefits that agencies can derive in using the standard. While the bulletin highlights several critical issues that federal agencies need to consider, agencies should rely on FIPS 140-1 for precise applicability statements, requirements, and policy for use.
FIPS 140-1 as a Framework Standard
A cryptographic module is that part of a system or application that provides cryptographic services such as encryption, authentication or electronic signature generation and verification. A cryptographic module that is designed to meet FIPS 140-1 incorporates cryptographic algorithms and functions specified in related FIPS and other security features that are necessary for the security of the module. The standard is flexible in that it allows application or program managers to choose the robustness of the security features and functionality that is needed. The standard specifies four increasing security levels to allow for cost-effective cryptographic solutions that are appropriate for different degrees of data sensitivity and different application environments. FIPS 140-1 defines the framework for NIST's current and future cryptographic standards.
Federal Standard (FS) 1027, General Security Requirements for Equipment Using the Data Encryption Standard, was issued by the General Services Administration in 1982. The standard prescribed the minimum general security requirements for the implementation of the Data Encryption Standard (DES) in telecommunications equipment and systems used by the federal government. The responsibility for FS 1027 was transferred to NIST in 1988 and FS 1027 was redesignated as FIPS 140.
NIST recognized the need to revise FIPS 140 to reflect the evolving needs of users and manufacturers, and to incorporate current trends and capabilities in technology. A notice was published in the Federal Register in 1988 to solicit the views of industry, the public, and federal, state and local governments regarding the planned revision of FIPS 140. NIST received numerous comments which encouraged the planned revision and offered specific suggestions for changes.
The resulting revised standard, FIPS 140-1, Security Requirements for Cryptographic Modules, was developed by a committee of government and industry participants which was organized by NIST in 1989. A Federal Register notice in 1991 announced the proposed revision of the standard and requested comments from government and industry. Numerous comments and suggestions were received, many of which were incorporated into the final version of the standard. On January 11, 1994, NIST issued FIPS 140-1 as an approved standard, with an effective date of June 30, 1994.
For all federal agencies, including defense agencies, the use of encryption products which conform to FIPS 140-1 is mandatory for the protection of sensitive unclassified information when the agency determines that cryptographic protection is required. Note that information covered by 10 U.S.C. 2315, commonly referred to as the Warner Amendment, is excluded from this requirement. Agencies are required to use the standard in designing, acquiring, and implementing cryptographic-based security systems within computer and telecommunications systems (including voice systems).
Definition of a Cryptographic Module
A cryptographic module (cryptomodule) is a set of hardware, firmware or software, or some combination thereof, that implements cryptographic logic or processes. Examples include a standalone piece of equipment such as a link encryptor, an add-on encryption board embedded into a computer system, and a software application running on a microprocessor such as a digital signature application that services many other applications. If the cryptographic logic is implemented in software, then the processor which executes the software is also part of the cryptographic module.
Structure of the Standard
FIPS 140-1 identifies eleven areas of security requirements over the following four security levels: The Level 1 requirements of the standard specify the basic security requirements for a cryptographic module (e.g., the encryption algorithm must be FIPS-approved). No physical security mechanisms are required for the module beyond the requirement for production-grade equipment. Level 1 allows the use of integrated circuit (IC) cards (i.e., smart cards) and software implementations which are utilized in general purpose, single-user personal computers (PC). NIST believes that such implementations are often appropriate in low-level security applications. Smart cards enhance the security of most systems. Since the card is kept in the user's possession, additional physical security measures are often not necessary. Many vendors use smart cards as a secure medium when distributing cryptographic keys. The implementation of PC cryptographic software may be more cost-effective than hardware-based mechanisms.
Level 2 improves on the physical security of a Level 1 cryptographic module by adding the requirement for tamper evidence through the use of tamper-evident coating or seals, or pick-resistant locks. These requirements provide a cost- effective means for physical security and avoid the cost of the higher level of protection required at Levels 3 and 4. The basic security concept is that the coating or seal placed on the module would have to be broken in order to attain physical access to the plaintext cryptographic keys and other critical security parameters within the cryptographic module. Level 2 provides role-based authentication which allows groups of users to utilize the services of the cryptographic module without each user being uniquely identified. For example, a set of security officers may all use their own copy of the same physical key that is inserted and turned to reset a cryptographic module to an operational status. The cryptographic module can authenticate that the user is a security officer; however, the module does not uniquely identify which officer.
Level 2 requirements also allow software cryptography in multi- user, multi-tasking systems when used in conjunction with a C2 or equivalent trusted operating system. The controls provided by a trusted operating system are needed to maintain the security necessary for protected information such as private or secret keys, authentication information, the algorithm software, and other necessary parameters.
A Level 3 cryptographic module has requirements that help to prevent an intruder from gaining access to the cryptographic keys, authentication data, and other security parameters held within the cryptographic module. The covers and doors of the module contain zeroization circuitry such that an unauthorized attempt to open a cover or door will zeroize the keys, authentication data, and other security parameters. The keys, authentication data, and other security parameters are input to the module through separate ports and trusted paths. The key management requirements at this level specify split-knowledge techniques. A split-knowledge technique ensures that a cryptographic key is under the control of two or more users. Each user has a key component which, individually, conveys no knowledge of the resultant key. Level 3 allows software cryptography in multi-user, multi-tasking systems when a B1 or equivalent trusted operating system is employed.
A Level 4 cryptographic module provides an envelope of protection around the cryptographic module. The intent of Level 4 protection is to detect a penetration of the device from any direction (rather than just attempts at the cover or door covered by Level 3 requirements) and respond by destroying critical information before it can be acquired. For example, if one attempts to cut through the cover of a cryptographic module, the attempt should be detected and all critical security parameters should be zeroized. Level 4 allows software cryptography in multi-user, multi-tasking systems when a B2 or equivalent trusted operating system is employed. A B2 operating system provides a large number of assurances of the correct operation of the security features of the operating system.
The Eleven Security Requirements Areas
Cryptographic Module Specification requirements ensure that the cryptographic module is explicitly defined. Modules must have defined hardware components, software components, and firmware components if applicable. The module must have a stated security policy that is reflected in the design and intended use of the module. The module must have every operational and error state defined as specified in the Finite State Machine Model requirements. The requirements in these areas help agencies to determine exactly what a particular cryptographic product consists of, help ensure that vendors use good design techniques in building a cryptographic module, and allow NIST to more easily determine if the requirements for a particular module have been met.
Module Interface requirements help ensure that all information flow and physical access to and from the module are well-defined and controlled. At the higher security levels, requirements help ensure that critical information such as authentication information and cryptographic keys are not compromised when entered or output from the module.
Roles and Services requirements help ensure that the module supports defined authorized roles and corresponding services. The module must also provide a mapping of the services to the roles. At Level 2, the module must be able to authenticate that an operator of the module can assume a specific role (i.e., role- based authentication). At Levels 3 and 4, the module must be able to uniquely authenticate the operator (identity-based authentication).
Physical Security requirements help restrict unauthorized physical access to the contents of the module and to deter unauthorized use or unauthorized modification of the module. Level 1 requires standard protection provided by production-grade techniques. Level 2 requires that modules can show evidence of tampering. Level 3 requires that modules zeroize unprotected cryptographic keys, authentication data, and other important information when the module detects tampering or an unauthorized access attempt through the cover or doors of the module's enclosure. Level 4 requires that modules respond as in Level 3; however, the module must detect tampering or attempts anywhere on the module's enclosure.
Software Security requirements apply to security-relevant software or firmware that may be contained within the module. These requirements help ensure that the software corresponds to and has correctly implemented the defined security policy of the module. At Level 4, more vigorous requirements require formal proof of this correspondence.
Operating System Security requirements help protect cryptographic software implementations in modules where untrusted software will also be used. The Level 1 requirements allow software cryptographic functions to be run on a general-purpose PC. Requirements at the higher levels help ensure the security of software cryptography in multi-user, time-shared systems by requiring a trusted operating system.
Key Management requirements help ensure the security of cryptographic keys throughout the cryptographic key life cycle. Requirements in this area relate to key generation, distribution, entry, use, storage, destruction, and archiving. FIPS approved methods are required for key generation and distribution. However, until a FIPS approved public key-based key distribution technique is established, commercially available public key methods may be used (e.g., the Diffie-Hellman public key distribution technique). To prevent the compromise of electronically distributed secret or private keys, requirements specify that the keys should always be entered into or out of the module in encrypted form. Manually distributed keys, which should be protected using safeguards and procedures that are beyond the scope of this standard, can be entered or output from the module in plaintext form at Levels 1 and 2. Levels 3 and 4 requirements provide for applications where dual control of keys are needed. This requires the module to support key entry by either entering the key in encrypted form or using split- knowledge procedures. Split-knowledge procedures force the key to be entered or output as two key components.
The Cryptographic Algorithm requirement mandates that the module implement a FIPS approved cryptographic algorithm. The current FIPS approved cryptographic algorithms include: the Data Encryption Standard (FIPS 46-2) and the Escrowed Encryption Standard (FIPS 185) for encryption; the Computer Data Authentication Standard (FIPS 113) and the Digital Signature Standard (FIPS 186) for authentication and signature generation/verification; and the Secure Hash Standard (FIPS 180- 1) for use when a secure hash algorithm is required. Modules must meet the requirements within the respective standard of the implemented algorithm. In addition to FIPS approved algorithms, products may also contain other algorithms that are not FIPS approved. However, an algorithm that is not FIPS approved may not be used in lieu of the FIPS approved algorithm for government applications.
Self-Test requirements help ensure that the cryptographic processing of the module is operating correctly. These self- tests check the cryptographic algorithm, software, and firmware integrity and other vendor-defined critical functions.
Effective Use of FIPS 140-1
The following steps are recommended when implementing a
Selecting an Appropriate Level
An application or program manager need not choose the same level for all eleven requirements. The standard's flexibility allows for choosing different levels among the eleven requirement areas. Using this flexibility is encouraged. As an example, consider an organization that will be using a digital signature generation and verification software implementation on a multi-tasking, multi-user operating system. The organization determines the need to use a trusted operating system to protect the integrity and availability of the encryption software for all system users. The organization may require Level 2 Operating System requirements. The organization then determines that solid key management, including split-knowledge procedures, is critical in this application and requires Level 3 Key Management requirements. However, only Level 1 Physical Security requirements for the system are necessary since the controls and procedures used to maintain a secure facility and the personnel operating the system are adequate in protecting the system physically. As this example shows, a different level of the standard can be chosen for the different areas covered by the standard.
Determining Conformance to FIPS 140-1
The CMV Program validates cryptographic modules as conforming to FIPS 140-1. The National Voluntary Laboratory Accreditation Program (NVLAP), administered by NIST, accredits independent testing laboratories to perform the FIPS 140-1 tests. Vendors of cryptographic modules use these laboratories to have their modules tested. The accredited laboratories send the test results to NIST.
Based on the test results from these laboratories, NIST determines the level of conformance to the standard and issues an appropriate validation certificate of conformance. Since the initiation date of the CMV Program was July 17, 1995, NIST encourages federal agencies to begin specifying FIPS 140-1 validated products in their procurements. However, federal agencies may accept written affirmation from cryptomodule vendors as evidence of conformance to FIPS 140-1 until January 31, 1996. After that date, agencies should procure only those products that are either validated or have been submitted to an accredited testing laboratory for testing. After January 31, 1997, federal agencies should procure only products that have been validated by NIST under the CMV Program. The list of validated products is available electronically at http://csrc.ncsl.nist.gov.
Products that have been endorsed by the National Security Agency as meeting FS 1027, or have been affirmed in writing as meeting FIPS 140, can be purchased without NIST validation until June 30, 1997. After that date, agencies should purchase products only if they have been NIST-validated. Agencies that purchase equipment under the conditions above may continue to use the equipment without requiring further affirmation or validation for conformance to this standard. NIST maintains a list of products that are available under the FS 1027 and FIPS 140 provisions.
For More Information
FIPS 140-1, the validated products list, and a listing of NVLAP
accredited laboratories are available electronically at
http://csrc.ncsl.nist.gov. FIPS 140-1 can also be obtained in
hard copy from the National Technical Information Service (NTIS)
at (703) 487-4650. Questions regarding the CMV Program should
directed to Lisa J. Carnahan at (301) 975-3362 or