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ICE (cipher) - Definition and Overview |
| Related Words: Greek, X, Add, Allegory, Argot, Autograph, Bit, Break, Calculate, Cant, Cast, Character, Code |
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| ICE
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ICE_(cipher)_InfoBox_Diagram.png
The ICE f-function.
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| General
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| Designer(s) | Matthew Kwan
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| First published | 1997
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| Derived from | (DES)
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| Cipher(s) based on this design | -
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| Algorithm detail
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| Block size(s) | 64 bits
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| Key size(s) | 64 bits for ICE, 64n for ICE-n
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| Structure | Feistel network
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| Number of rounds | 16 for ICE, 8 for Thin-ICE, 16n for ICE-n
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| Best cryptanalysis
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| Differential cryptanalysis can break 15 out of 16 rounds of ICE with complexity 256. Thin-ICE can be broken using 227 chosen plaintexts with a success probability of 95%.
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In cryptography, ICE (Information Concealment Engine) is a block cipher published by Kwan in 1997. The algorithm is similar in structure to DES, but with the addition of a key-dependent bit permutation in the round function. The ICE algorithm is not subject to patents, and the source code has been place into the public domain.
ICE is a Feistel network with a 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. A open-ended variant, ICE-n, uses 16n rounds with 64n 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 223 chosen plaintexts with a 25% success probability. If 227 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 256 work and at most 256 chosen plaintexts.
References
- Matthew Kwan, The Design of the ICE Encryption Algorithm, Fast Software Encryption 1997, pp69–82 [1] (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, pp270–283 (PDF) (http://www.cosic.esat.kuleuven.ac.be/publications/article-120.pdf).
External links
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