REBC2 cipher

Abstract

REBC2 is a new cryptosystem based on the rotor enhanced block cipher which was proposed by the authors in NRSC 2002. The concept of a rotor enhanced block cipher is considered from a new point of view, which is to use rotors to achieve two basic cryptographic operations: permutation, and substitution. A round key is generated using rotor too from the previos rounds' key. That generated key is used to achieve ciphertext key dependency. To enhance non-linearity and to resist linear cryptanalysis, REBC2 has variable block and key lengths. Each round has its own block length which depends on rounds' key length Another feature of REBC2 is that the used rotors are not ordinary rotating arrays containing large amount of static data, but are rather implemented using round key dependent mathematical linear expressions, which was firstly proposed by the authors in KAMFEE. This produced less memory for implementation, normalized ciphertext statistics, and low processing speed trend.