Threefish Algorithm

Threefish is a symmetric-key tweakable block cipher designed as part of the Skein hash function, an entry in the NIST hash function competition. It uses no S-boxes or other table lookups, drawing its nonlinearity instead from alternating additions with exclusive-or operations to avoid cache-timing attacks, placing it in the same family of approach as Salsa20 and TEA. Threefish and Skein were designed by a team including Bruce Schneier and Niels Ferguson, and the cipher is unpatented and license-free.