How to Construct Cryptographic Primitives from Stream Ciphers

Abstract

A general stream cipher with memory (SCM) mode in which each ciphertext symbol depends both on the current and on the previous plaintext symbols is pointed out. It is shown how to convert any keystream generator into the SCM mode and the security of both the modes is discussed. It is proposed how to construct secure self-synchronizing stream ciphers, keyed hash functions, hash functions, and block ciphers from any secure stream cipher in the SCM mode. Rather new and unusual designs can thus be obtained, such as the designs of block ciphers and (keyed) hash functions based on clock-controlled shift registers only.