| Nimbus | |
| Designers: | Alexis Machado |
| Publish Date: | 2000 |
| Key Size: | 128 bits |
| Block Size: | 64 bits |
| Rounds: | 5 |
| 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 ofencryption. 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.[1]
Nimbus was broken by Vladimir Furman; he found a differential attack using only 256 chosen plaintexts.[2]