  Sosemanuk is a new synchronous software-oriented stream cipher, corresponding
to Profile 1 of the ECRYPT call for stream cipher primitives. Its key length is
variable between 128 and 256 bits. It ac- commodates a 128-bit initial value.
Any key length is claimed to achieve 128-bit security. The Sosemanuk cipher
uses both some basic design principles from the stream cipher SNOW 2.0 and some
transformations derived from the block cipher SERPENT. Sosemanuk aims at
improv- ing SNOW 2.0 both from the security and from the efficiency points of
view. Most notably, it uses a faster IV-setup procedure. It also requires a
reduced amount of static data, yielding better performance on several
architectures.
