User guide

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Appendix A. Encryption Standards
A.1. Synchronous Encryption
A.1.1. Advanced Encryption Standard - AES
In cryptography, the Advanced Encryption Standard (AES) is an encryption standard adopted by the
U.S. government. The standard comprises three block ciphers, AES-128, AES-192 and AES-256,
adopted from a larger collection originally published as Rijndael. Each AES cipher has a 128-bit block
size, with key sizes of 128, 192 and 256 bits, respectively. The AES ciphers have been analyzed
extensively and are now used worldwide, as was the case with its predecessor, the Data Encryption
Standard (DES).
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A.1.1.1. AES Uses
A.1.1.2. AES History
AES was announced by National Institute of Standards and Technology (NIST) as U.S. FIPS PUB 197
(FIPS 197) on November 26, 2001 after a 5-year standardization process in which fifteen competing
designs were presented and evaluated before Rijndael was selected as the most suitable (see
Advanced Encryption Standard process for more details). It became effective as a standard May 26,
2002. It is available in many different encryption packages. AES is the first publicly accessible and
open cipher approved by the NSA for top secret information (see Security of AES, below).
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The Rijndael cipher was developed by two Belgian cryptographers, Joan Daemen and Vincent
Rijmen, and submitted by them to the AES selection process. Rijndael (pronounced [r�inda�l]) is a
portmanteau of the names of the two inventors.
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A.1.2. Data Encryption Standard - DES
The Data Encryption Standard (DES) is a block cipher (a form of shared secret encryption) that
was selected by the National Bureau of Standards as an official Federal Information Processing
Standard (FIPS) for the United States in 1976 and which has subsequently enjoyed widespread use
internationally. It is based on a symmetric-key algorithm that uses a 56-bit key. The algorithm was
initially controversial with classified design elements, a relatively short key length, and suspicions
about a National Security Agency (NSA) backdoor. DES consequently came under intense academic
scrutiny which motivated the modern understanding of block ciphers and their cryptanalysis.
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A.1.2.1. DES Uses
A.1.2.2. DES History
DES is now considered to be insecure for many applications. This is chiefly due to the 56-bit key
size being too small; in January, 1999, distributed.net and the Electronic Frontier Foundation
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"Advanced Encryption Standard." Wikipedia. 14 November 2009 http://en.wikipedia.org/wiki/Advanced_Encryption_Standard
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"Advanced Encryption Standard." Wikipedia. 14 November 2009 http://en.wikipedia.org/wiki/Advanced_Encryption_Standard
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"Advanced Encryption Standard." Wikipedia. 14 November 2009 http://en.wikipedia.org/wiki/Advanced_Encryption_Standard
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"Data Encryption Standard." Wikipedia. 14 November 2009 http://en.wikipedia.org/wiki/Data_Encryption_Standard