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419 Mar 2015 - 13:52sever408? 
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You are here: UMWiki>CBI_ComputerSecurity Web>Mechanisms>MechanismsTripleDES (19 Mar 2015, sever408)

Current Activitieslock Who is Who?lock People Programs Publications CSHW_2014 Systems Events Mechanisms

Triple-DES (Data Encryption Standard)

Triple-DES is an encryption standard that describes the Triple Data Encryption Algorithm (TDEA, used interchangeably with TDES), which applies the Data Encryption Algorithm multiple times with different keys to enhance encryption strength. NIST has authorized Federal organizations to use TDEA to protect sensitive, unclassified data.(1)

Rationale behind TDES

Single DES was created in the 1970's, containing a "key size" that even then was considered small. In the late 90's, the security company RSA issued "challenges" with cash prizes for decrypting a partial known plaintext phrase, half of which was disclosed to competitors, with knowledge of the latter half serving as proof that the encryption had been broken.(2) The first challenge broke the key in less than three months, using only computers volunteered by private individuals -- home PCs, in other words. Further challenge winners broke the key in a matter of hours, using dedicated hardware well within the economic limits of a foreign government. As it became clear to US officials that DES could now be broken by both distributed and super-computing methods, NIST began developing the Advanced Encryption Standard(3), as well as exploring stopgap measures while that was being developed. The third challenge discovered the secret DES key in 22 hours on January 18th, 1999; the same year, a revision of the NIST document banned the implementation of DES in new systems.

Public Recognition

TDEA was first authorized for Federal cryptographic use in a Federal Information Processing Standards publication in 1999, replacing DEA as the preferred symmetric key encryption scheme. DEA only retained NIST approval for use in legacy systems.(4) In 2005, FIPS 46-3 was withdrawn by order of the Secretary of Commerce, downgrading the use of TDEA from a standard, to a "phase-out" stage in which DEA has been totally disallowed from securing sensitive data and TDEA is an approved method only until 2030. This 2030 sunset is intended to give organizations time to transition to AES, which has been approved for use with both unclassified and classified Federal information.(5)(6)(7)


1 : http://csrc.nist.gov/publications/nistpubs/800-67-Rev1/SP-800-67-Rev1.pdf

2 : Reports from the winners of each of the three contests can be found here: DES-I, DES-II, DES-III (and also http://www.distributed.net/DES).

3 : http://csrc.nist.gov/archive/aes/pre-round1/aes_9701.txt

4 : FIPS 46-3, section 12

5 : http://www.gpo.gov/fdsys/pkg/FR-2005-05-19/pdf/05-9945.pdf

6 : http://csrc.nist.gov/publications/nistpubs/800-67-Rev1/SP-800-67-Rev1.pdf

7 : http://csrc.nist.gov/groups/ST/toolkit/documents/aes/CNSS15FS.pdf

Topic revision: r4 - 19 Mar 2015 - 13:52:44 - sever408
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