Joint Encryption and Channel Coding Scheme Based on Balancing Indices and Polar Codes

A joint encryption and channel coding scheme is proposed in this paper. The proposed scheme takes advantage of the structure of balanced codes to reduce the encryption cost. We easily encrypt each codeword of polar codes to a stream cipher with its balancing index as the secret key and encrypt the balancing indices with a novel private-key cryptosystem which is based on the special structure of polar codes. Our private-key cryptosystem has the same timing complexity as polar codes with a shorter key size than the existing cryptosystems, as well as is quite secure against brute force attack and some well-known chosen-plaintext attacks. The proposed joint scheme makes the encryption easily and can efficiently reduce the error diffusion than the traditional schemes in which encryption and channel coding are handled separately. Compared with the original polar codes, it will only have a negligible loss in the code rate while remaining the same error-correcting ability, which is suitable for processing large volumes of data.