University College of Dublin
Modifications of Arithmetic Coding (AC) is to improve the security in two methods are: RAC (Randomized Arithmetic Coding) and KSAC (AC with Key-based interval Splitting). For the security, encryption uses AC that is based on the inability of the opponent to distinguish between the encryption of one plaintext from the encryption of another. Chosen plaintext attacks are insecure in RAC, because same key is used to encrypt different messages even random key is used for compress every messages. The new encryption scheme is used for improve security in RAC that is the encryption is performed by a bit wise X-OR of the compressed output with the pseudorandom bit sequence for chosen plaintext attacks.