This paper proposes a block crypto system that uses cyclic geometric progressions over polynomial rings as encryption function, and its encryption diagram is based on unbalanced Feistel network with four branches. All the sub keys in encryption steps are also elements in cyclic geometric progressions over polynomial ring with two cyclotomic cosets. By using this crypto system, we apply to a hash function with 512 bits output length. Some diffusion simulations of the proposed crypto system and hash function are also presented. | A method of buiding a crypto system based on unbalanced feistel network and its application in hash functions
