Simultaneous Compression and Encryption using Arithmetic Coding with Randomized Bits

—Providing compression and security simultaneously is important because of increased use of compressed media files in many applications such as the internet, digital cameras, and portable music players . We first give a definition for security of encryption using arithmetic coding that is based on the inability of the adversary to distinguish between the encryption of one plaintext from the encryption of another.we prove that randomized arithmetic coding is insecure even if a new random key is used to compress every message.Our proof assumes that the adversary can only eavesdrop on the cipher text and cannot request encryptions of chosen-plaintexts. In this paper we proposed a new method first-compress-then-encrypt,where compression is performed using arithmetic coding with equal interval splitting and encryption is performed by a bitwise XOR of the compressed output with a pseudorandom bit sequence, is provably secure with respect to chosen-plaintext attacks.Our proposed work reduces delay during transmission of data and increase security