Currently, there exist four FIPS-approved symmetric key algorithms for encryption: Advanced Encryption Standard (**AES**), Data Encryption Standard (**DES**), **Triple-DES**, and **Skipjack**. *AES is the FIPS-Approved symmetric encryption algorithm of choice*.

- FIPS 197,
*Advanced Encryption Standard (AES)*, specifies the AES algorithm. *Recommendation for the Triple Data Encryption Algorithm (TDEA) Block Cipher*, NIST Special Publication 800-67, May 2004.*Recommendation for Block Cipher Modes of Operation, Methods and Techniques*, Special Publication 800-38A, December 2001. Appendix E references Modes of Triple-DES.*Triple Data Encryption Algorithm Modes of Operation*, ANSI X9.52-1998.**Copies of X9.52-1998 may be obtained from X9**, a standards committee for the financial services industry. NIST does NOT have copies of the standard available for distribution.- The Skipjack algorithm is referenced in FIPS 185,
*Escrowed Encryption Standard (EES)*, and a complete specification is available in*SKIPJACK and KEA Algorithm Specifications (Version 2.0, 29 May 1998)*.

- AES tests are described in The Advanced Encryption Standard Algorithm Validation Suite (AESAVS).
- Triple-DES tests are described in NIST Special Publication 800-20,
*Modes of Operation Validation System for the Triple Data Encryption Algorithm (TMOVS): Requirements and Procedures*. An additional test, the Multi-block Message Text (MMT), is also required. - Skipjack tests are described in NIST Special Publication 800-17,
*Modes of Operation Validation System (MOVS): Requirements and Procedures*.

- AES Known Answer Test (KAT) Vectors - This file provides an electronic version of the KAT vectors that can be used to informally verify the correctness of an AES algorithm implementation, using the Known Answer Test (KAT) described in The Advanced Encryption Standard Algorithm Validation Suite (AESAVS).
*However, use of these vectors does***not**take the place of validation obtained through the Cryptographic Module Validation Program. - Triple-DES Sample Vectors - This file provides sample vectors that can be used to informally verify the correctness of a Triple-DES implementation, using the Monte Carlo Tests described in NIST Special Publication 800-20.
*However, use of these vectors does***not**take the place of validation obtained through the Cryptographic Module Validation Program.

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On February 15, 2000, NIST announced the approval of *FIPS 186-2 with Change Notice 1 dated October 5, 2001*, *Digital Signature Standard (DSS)*, which supersedes FIPS 186-1. This standard specifies three FIPS-approved algorithms for generating and verifying digital signatures:

**Digital Signature Algorithm (DSA),****RSA (as specified in ANSI X9.31), and****Elliptic Curve DSA (ECDSA; as specified in ANSI X9.62).**

New items in the DSS include:

- the approval of Elliptic Curve DSA (ECDSA) as specified in ANSI X9.62,
- a list of recommended elliptic curves for Federal Government use (see Appendix 6 of
*FIPS 186-2 with Change Notice 1 dated October 5, 2001*), and - an allowance for the continued acquisition of implementations of PKCS#1 for a transition period of eighteen (18) months.

Copies of the **ANSI X9.31** and **ANSI X9.62** standards are available from X9, a standards committee accredited by the American National Standards Institute (ANSI). NIST does NOT have copies of these standards available for distribution.

All three digital signature techniques in FIPS 186-2 (with Change Notice 1 dated October 5, 2001) make use of the Secure Hash Algorithms specified in FIPS 180-2 (with Change Notice 1 dated February 25, 2004), *Secure Hash Standard (SHS)* accessible via the hashing section of this webpage.

DSA, RSA, and ECDSA are currently the *only* FIPS-approved methods for digital signatures.

The testing requirements are specified in:

**Digital Signature Algorithm Validation System (DSAVS)**

**Additional testing note:** For the Domain Parameter Generation and Verification, and the Signature Generation and Verification functions, the underlying SHA-1 algorithm must be validated as part of the DSA validation. In a future release, the other SHA algorithms will be supported.

**RSA Validation System (RSAVS)**

**Beginning September 28, 2006:** Validation testing for RSA algorithm implementations of the RSASSA-PKCS1-v1_5, as specified in *Public Key Cryptography Standards (PKCS) #1 v2.1: RSA Cryptography Standard-2002*, and the RSA X9.31 algorithms include additional testing to assure the encoded message EM and the intermediate integer IR are in the correct formats. This testing verifies that an implementation under test (IUT) does not contain a potential implementation design that could introduce a vulnerability in these algorithms. This testing has been added to the Signature Verification validation test described in the RSAVS document. No modification to this document was necessary to add this feature. Below in the Test Vectors section, there are test vectors available to informally test if this vulnerability exists in an implementation.

For all validated cryptographic modules that incorporate RSA, the CMVP and CAVP strongly suggest re-testing of the RSA algorithmic implementations to determine if the vulnerability is present.

If new CAVP testing is performed and the vulnerability is determined not to be present, the CMTL can submit the new test results to the CAVP along with a letter indicating that the implementation passed the RSA testing in CAVS5.2 and the vulnerability is not present. The letter should request that a new algorithm certificate be printed to replace the already issued certificate referencing the new version of CAVS. Please indicate the already issued certificate number. This letter should be included in the zip file along with the other files. Note that the certificate number will not change. Only the reference to the version of the CAVS tool and the signatory date will be changed. (Note the validation request will be submitted using already established procedures.)

If CAVP testing is performed and the vulnerability is discovered, the following revalidation process shall be followed:

- The algorithm implementation is changed to remove the vulnerability resulting in a different version number,
- Submit the new test results to the CAVP for the new version of the implementation. A new algorithm certificate will be issued for the new version of the implementation. The certificate will reference CAVS5.2.

**Additional testing note:** For the RSA functions, all underlying SHA algorithm(s) supported by the RSA implementation must be validated as part of the RSA validation.

**Eliptic Curve Digial Signature Algorithm (ECDSA) Validation System (ECDSAVS)**

**Additional testing note:** For the Signature Generation and Verification functions, the underlying SHA-1 algorithm must be validated as part of the ECDSA validation. In a future release, the other SHA algorithms will be supported.

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The Secure Hash Algorithms (SHA-1, SHA-224, SHA-256, SHA-384, and SHA-512) are specified in FIPS 180-2 with Change Notice 1 dated February 25, 2004, *Secure Hash Standard (SHS)*.

- SHA Test Vectors for Hashing Bit-Oriented Messages
- SHA Test Vectors for Hashing Byte-Oriented Messages

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The algorithms for generating approved random numbers are referenced in FIPS 140-2 Annex C.

- FIPS 186-2 with Change Notice 1 dated October 5, 2001 (Appendix 3.1 and 3.2)
**ANSI X9.31**(Appendix A.2.4) -*Using 2-Key Single DES*- NIST-Recommended Random Number Generator based on ANSI X9.31 Appendix A.2.4 using the 3-Key Triple DES and AES algorithms
**ANSI X9.62**(Appendix A.4).

Copies of the ANSI X9.31 and ANSI X9.62 standards are available from X9, a standards committee accredited by the American National Standards Institute (ANSI). NIST does NOT have copies of these standards available for distribution.

The testing requirements for these algorithms can be found in the document titled The Random Number Generator Validation System (RNGVS).

*SP
800-90 Recommendation for Random Number Generation Using Deterministic
Random Bit Generators (Revised_March2007)* specifies mechanisms
for the generation of random bits using deterministic methods. There
are four mechanisms discussed in this Special Publication. These mechanisms
are based on either hash functions (Hash_DRBG, HMAC_DRBG), block cipher
algorithms using Counter mode (CTR_DRBG ) or number theoretic (Dual
EC_DRBG) problems.

DRBG Test Vectors - These files provide an electronic version of the
test vectors that can be used to informally verify the correctness of
a DRBG algorithm implementation using the DRBGVS. **However,
use of these vectors does not take the place of validation obtained
through the Cryptographic Algorithm Validation Program (CAVP). **

DRBG Test Vectors
In this zip file, there are 3 text files. * Hashbased.txt*
contains test vectors for HASH_DRBG and HMAC_DRGB.

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The CMAC algorithm is specified in Special Publication 800-38B dated May 2005, Recommendation for Block Cipher Modes of Operation: The CMAC Mode for Authentication. CMAC can be considered a mode of operation of the block cipher because it is based on an approved symmetric key block cipher, such as the Advanced Encryption Standard (AES) algorithm currently specified in Federal Information Processing Standard (FIPS) Pub. 197. CMAC is also an approved mode of the Triple Data Encryption Algorithm (TDEA).

The Counter with Cipher Block Chaining-Message Authentication Code (CCM) is specified in Special Publication 800-38C dated May, 2004, Counter with Cipher Block Chaining-Message Authentication Code (CCM). CCM is based on an approved symmetric key block cipher algorithm whose block size is 128 bits, such as the Advanced Encryption Standard (AES) algorithm currently specified in Federal Information Processing Standard (FIPS) Pub. 197 [2]; thus, CCM cannot be used with the Triple Data Encryption Algorithm [3], whose block size is 64 bits. Currently the only NIST-Approved 128 bit symmetric key algorithm is AES.

The Keyed-Hash Message Authentication Code (HMAC) is specified in FIPS 198 dated March 6, 2002, Keyed-Hash Message Authentication Code (HMAC). This algorithm utilizes the Secure Hash Algorithms as an underlying primitive.

The automated conformance tests for FIPS 113 and 171 are no longer operational. Currently, if a FIPS 140-1 or FIPS 140-2 cryptographic module implements either of these two standards, the CMT testing laboratories perform some testing that these FIPS requirements are implemented correctly in the cryptographic module.