Nimbus (cipher)
Appearance
General | |
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Designers | Alexis Machado |
First published | 2000 |
Cipher detail | |
Key sizes | 128 bits |
Block sizes | 64 bits |
Rounds | 5 |
Best public cryptanalysis | |
Differential cryptanalysis can break Nimbus with 256 chosen plaintexts. |
In cryptography, Nimbus is a block cipher invented by Alexis Machado in 2000. It was submitted to the NESSIE project, but was not selected.
The algorithm uses a 128-bit key. It operates on blocks of 64 bits and consists of 5 rounds of encryption. The round function is exceedingly simple. In each round the block is XORed with a subkey, the order of its bits is reversed, and then it is multiplied mod 264 by another subkey, which is forced to be odd.
Nimbus was broken by Vladimir Furman; he found a differential attack using only 256 chosen plaintexts.
References
- Security evaluation of NESSIE first phase (PDF)
- Eli Biham, Vladimir Furman (November 29, 2000). "Differential Cryptanalysis of Nimbus" (PDF/PostScript). Retrieved February 8, 2007.
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