High Performance Implementation of Snow3G Algorithm in Memory Limited Environments

SNOW 3G is a stream cipher which forms the basis of the ciphering and integrity protection algorithms that have been mandated by 3GPP for protection of data over the air interface. The software implementation of this cipher is known to run very fast if a lookup table based approach is used. However, the use of look up tables introduces a need for 10 kB of memory to achieve optimal performance. This paper describes how the symmetry in the look up tables can be exploited in software implementation that uses only 4 kB of memory, without any significant loss in performance.