New Rotor Based Symmetric Cipher

This paper introduces a new cryptosystem developed on the concept of rotor enhanced block cipher which was proposed by the authors in NRSC 2002. The rotor enhanced block cipher concept was considered from a new point of view, which is to use rotors to achieve two basic cryptographic operations; permutation, and substitution. Round key is generated using rotor too. That generated key is used to achieve ciphertext key dependency. To enhance non-linearity and to resist linear cryptanalysis, the proposed cipher has a variable block, and key lengths. Each round has its own block length which depends on round the key and round key length. Dependency is based upon the pervious round generated key. Another feature of the proposed cipher is that the used rotors are not ordinary rotating arrays containing large amount of static data, but they are implemented using round key dependent mathematical linear expressions, which was firstly proposed by authors in KAMFEE. This achieved memory-less, equally ciphertext statistics, and small processing speed trend. The new proposed cipher can be considered as the second generation of REBC which was introduced by the authors.