Threefish

Three Fish is a block cipher that was developed as part of the design of cryptographic hash function Skein, which at the NIST - selection (English NIST hash function competition) participated to SHA -3. Three Fish does not use S-boxes or other lookup tables to temporal side-channel attacks ( attacks computation time ) to more difficult. The necessary non-linearities can be realized by alternating additions and logical XOR operations.

Fish is a so-called three tweakable Blockverschlüssung, which means that an additional control input of the nature of the permutations can be changed to a certain extent. This allows the operation for time-critical applications such as hard disk encryption to go cyclical changes in the encryption without the expense of data throughput, as in the comparatively time-consuming change of the primary key.

A part of the development team has worked together in the design of block ciphers Twofish and Blowfish, however, have a different structure.