Rotor cipher with time controlled key and encryption process (RTCKP)

This paper gives a new symmetric cryptosystem having a key dependent block length and key dependent rounds, enhanced by a rotor with controlled time and key. The plaintext block is divided into basic sub-blocks each of thirty-two bits in length. The new proposal can encrypt blocks of plaintext of length 256, 512, or 1024 bits into blocks of the same length. Also the key length can be 256, 512, or 1024 bits. The total number of rounds depends on the key length. It uses thirty-two bits S-boxes implemented using thirty-two bits affine transformation modulo 2³² addition and thirty-two bits XORING are used followed by modulo 2³² + 1 multiplication. The secret key is encrypted using a key rotor to avoid any weakness points in the user keys. The proposal performs a complex set of operations on the encrypted secret key to produce a set subkeys. Also it uses three banks of rotors. The first bank performs the encryption process. It uses sixteen cylinders operating on all the 256 ASCII characters arranged using a local time array. The second bank has four cylinders that are used in three operations. The first operation is to encrypt the user key. In this step, the rotor is arranged by the local time array of length t. The second operation is to encrypt the local time array. In this step, the user key arranges the rotor. The third operation is used to encrypt each letter of plaintext. The resulting output is then used in index bank to determine which cylinder in the first bank will turn after this letter is encrypted. The proposed algorithm is compared with the well known DES, AES and REBC symmetric systems and gives excellent results from the point of view of the security characteristics and the statistics of the ciphertext.