An error ‐ correcting stream cipher design with state ‐ hopping architecture

A new architecture of stream cipher based on state-hopping shift registers and a pseudorandom vector generator (PRVG) is introduced. The proposed stream cipher merges secrecy coding and channel coding into one processing step. It could be either a pure cryptosystem or a secrecy-channel coding by demand. Considered as cryptography, the PRVG generates pseudo random vectors which are treated as keystreams setting up the encryption scheme. This is different from the general concept in stream ciphers, state-hopping shift registers do not generate a pseudo random sequence but act as substitutions on plaintexts. Viewed as channel coding, the state-hopping shift registers play as the ones in convolution code and the PRVG generates a sequence of pseudorandom vector to determine the Trellis diagram. If the system acts as a pure cryptosystem, the decoding scheme is exactly the inverse of the encryption scheme. When the error-correcting ability is chosen, a modified sequential decoding is proposed.