ICE (cipher) 1188540 217174969 2008-06-04T22:44:10Z Apokrif 173030 [[Category:Feistel cipher]] {{Infobox block cipher | name = ICE | image = [[Image:ICE (cipher) InfoBox Diagram.png|280px|center]] | caption = The ICE Feistel function | designers = Matthew Kwan | publish date = 1997 | derived from = [[Data Encryption Standard|DES]] | derived to = | key size = 64 bits (ICE), 64&times;''n'' bits (ICE-''n'') | block size = 64 bits | structure = [[Feistel network]] | rounds = 16 (ICE), 8 (Thin-ICE), 16&times;''n'' (ICE-''n'') | cryptanalysis = [[Differential cryptanalysis]] can break 15 out of 16 rounds of ICE with complexity 2<sup>56</sup>. Thin-ICE can be broken using 2<sup>27</sup> chosen plaintexts with a success probability of 95%. }} In [[cryptography]], '''ICE (Information Concealment Engine)''' is a [[block cipher]] published by Kwan in 1997. The algorithm is similar in structure to [[Data Encryption Standard|DES]], but with the addition of a key-dependent bit permutation in the round function. The key-dependent bit permutation is implemented efficiently in software. The ICE algorithm is not subject to patents, and the source code has been placed into the public domain. ICE is a [[Feistel network]] with a [[block size (cryptography)|block size]] of 64 bits. The standard ICE algorithm takes a 64-bit key and has 16 rounds. A fast variant, '''Thin-ICE''', uses only 8 rounds. An open-ended variant, '''ICE-''n''''', uses 16''n'' rounds with 64''n'' bit key. Van Rompay et al (1998) attempted to apply [[differential cryptanalysis]] to ICE. They described an attack on Thin-ICE which recovers the secret key using 2<sup>23</sup> [[chosen plaintext]]s with a 25% success probability. If 2<sup>27</sup> chosen plaintexts are used, the probability can be improved to 95%. For the standard version of ICE, an attack on 15 out of 16 rounds was found, requiring 2<sup>56</sup> work and at most 2<sup>56</sup> chosen plaintexts. ==References== * Matthew Kwan, The Design of the ICE Encryption Algorithm, Fast Software Encryption 1997, pp69&ndash;82 [http://www.darkside.com.au/ice/paper.html]. * Bart van Rompay, Lars R. Knudsen and Vincent Rijmen, Differential Cryptanalysis of the ICE Encryption Algorithm, Fast Software Encryption 1998, pp270&ndash;283 [http://www.cosic.esat.kuleuven.ac.be/publications/article-120.pdf (PDF)]. ==External links== * [http://www.darkside.com.au/ice/index.html The ICE Home Page] * [http://www.darkside.com.au/ice/slides/slide01.htm The ICE information slides] {{Crypto navbox | block}} [[Category:Feistel cipher]] [[fr:ICE (cryptographie)]]