Advanced Encryption Standard (AES), Data Encryption Standard (DES), Triple-DES, and Skipjack Algorithms

• Overview:
  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.

  • FIPS 46-3, Data Encryption Standard (DES), specifies the DES and Triple-DES algorithms. For the complete specification of Triple-DES, the standard ANSI X9.52-1998, Triple Data Encryption Algorithm Modes of Operation, must be used in conjunction with FIPS 46-3. 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.

    Details on the security of DES and the migration from DES to Triple-DES are discussed in FIPS 46-3.

  • 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).

  FIPS 81, DES Modes of Operation, specifies several modes of operation for the DES and Skipjack algorithms. ANSI X9.52-1998 specifies seven (7) modes of operation for Triple-DES.

• Testing Requirements:
  Validation testing for AES, Triple-DES, DES, and Skipjack algorithms are handled by the Cryptographic Module Validation (CMV) Program's CMT labs.
  • 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.

  • DES and Skipjack tests are described in NIST Special Publication 800-17, Modes of Operation Validation System (MOVS): Requirements and Procedures. The DES algorithm also requires the completion of the MMT tests.

• Validation List:
  NIST maintains validation lists for AES, Triple-DES, DES, and Skipjack. These lists identify the algorithm implementations which have been tested as correctly implementing the AES, Triple-DES, DES, and Skipjack algorithms. Points of contact and implementation descriptions are also included.

• Other Information:
  
  • 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.

  • The announcement of FIPS 46-3 is available, which specifies the use of Triple-DES.

  • Additional information on DES (including a list of "dual" keys) may be found in FIPS 74, "Guidelines for Implementing and Using DES"

Last Modified: April 17, 2002
Computer Security Division
National Institute of Standards and Technology