Symmetric Key Cryptosystem Based on Randomized Block Cipher

Multimedia data encryption attempts to prevent unauthorized disclosure of confidential multimedia information in transit or storage. Security of multimedia files attracts more and more attention and many encryption methods have been proposed in literature. If we call a multimedia data stream (message) plaintext , the process of transforming the plaintext into unintelligible data stream is referred to as multimedia encryption (MME) where the encrypted message (data stream) is often named ciphertext. The process of transforming the ciphertext back into plaintext is termed decryption. We propose a new block cipher based on randomized key of size n × n where n is the block size and the block undergoes n² iterations with the plaintext. Every iteration generates the pseudo cipher text. The encryption process generate the ciphertext C with the help of the randomized key. The decryption apply the key in reverse order on the cipher text, to get back the plain text. This work deals with the problem of efficient multimedia data encryption.