The '''Data Authentication Algorithm''' ('''DAA''') is a former [[Federal Information Processing Standard|U.S. government standard]] for producing cryptographic [[message authentication code]]s. According to the standard, a code produced by the DAA is called a '''Data Authentication Code''' ('''DAC'''). The algorithm is not considered secure by today's standards.▼
{{More citations needed|date=July 2021}}
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▲The '''Data Authentication Algorithm''' ('''DAA''') is a former [[Federal Information Processing Standard|U.S. government standard]] for producing cryptographic [[message authentication code]]s. DAA Accordingis todefined thein standardFIPS PUB 113,<ref>[http://csrc.nist.gov/publications/fips/fips113/fips113.html aFIPS codePUB produced113 by– Computer Data Authentication] – the DAA[[Federal isInformation calledProcessing aStandard]] publication that defines the '''Data Authentication Code'''Algorithm</ref> ('''DAC''')which was withdrawn on September 1, 2008.{{Citation needed|date=July 2021}} The algorithm is not considered secure by today's standards.{{Citation needed|date=July 2021}}
According to the standard, a code produced by the DAA is called a '''Data Authentication Code''' ('''DAC'''). The algorithm [[Block cipher mode of operation#Cipher block chaining (CBC)|chain encrypts]] the data, with the last cipher block truncated and used as the DAC.
The DAA is equivalent to [[ISO/IEC 9797-1]] MAC algorithm 1, or [[CBC-MAC]], with [[Data Encryption Standard|DES]] as the underlying cipher, truncated to between 24 and 56 bits (inclusive).
==Sources==
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* [http://www.itl.nist.gov/fipspubs/fip113.htm FIPS PUB 113 - Computer Data Authentication] - the [[Federal Information Processing Standard]] publication that defines the Data Authentication Algorithm
Explanation: This standard specifies a Data Authentication Algorithm (DAA) which may be used to detect unauthorized modifications, both intentional and accidental, to data, The standard is based on the algorithm specified in the Data Encryption Standard (DES) Federal Information Processing Standards Publication (FIPS PUB) 46, and is compatible with both the Department of the Treasury's Electronic Funds and Security Transfer Policy and the American National Standards Institute (ANSI) Standard for Financial Institution Message Authentication (see cross index). The Message Authentication Code (MAC) as specified in ANSI X9.9 is computed in the same manner as the Data Authentication Code (DAC) specified in this standard. Similarly, the Data Identifier (DID) specified in this standard is sometimes referred to as a Message Identifier (MID) in standards related to message communications. The example given in Appendix 2 may be used when validating implementations of this standard.
