Method and system for performing permutations usin

专利名称：Method and system for performing

permutations using permutation instructionsbased on butterfly networks

发明人：Ruby B. Lee,Xiao Yang,Manish Vachharajani申请号：US09850237申请日：20010507

公开号：US20020031220A1公开日：20020314

专利附图：

摘要：The present invention provides permutation instructions which can be used insoftware executed in a programmable processor for solving permutation problems in

cryptography, multimedia and other applications. The permute instructions are based ona Benes network comprising two butterfly networks of the same size connected back-to-back. Intermediate sequences of bits are defined that an initial sequence of bits from asource register are transformed into. Each intermediate sequence of bits is used as inputto a subsequent permutation instruction. Permutation instructions are determined forpermitting the initial source sequence of bits into one or more intermediate sequence ofbits until a desired sequence is obtained. The intermediate sequences of bits aredetermined by configuration bits. The permutation instructions form a permutationinstruction sequence of at least one instruction. At most 21gr/m permutation instructionsare used in the permutation instruction sequence, where r is the number of k-bitsubwords to be permuted, and m is the number of network stages executed in oneinstruction. The permutation instructions can be used to permute k-bit subwords packedinto an n-bit word, where k can be 1, 2, . . . , or n bits, and k*r=n.

申请人：LEE RUBY B.,YANG XIAO,VACHHARAJANI MANISH

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