A secure information transmission scheme with a secret key based on polar coding

In this letter, a new secure information transmission scheme based on polar codes with a pre-shared secret key is proposed. In polar codes, after the channel polarization is induced, good split channels are used to transmit the user message and bad channels are utilized to support the reconstruction of the message by sharing fixed information. If the fixed information in bad channels is secret, an adversary gets difficulty in reconstructing the user message in good channels without knowledge of the fixed information. From this observation, we construct a secure information transmission scheme. By appending pre-/post-processing that imposes a dependency between the transmitted message sub-blocks, the adversary's difficulty can be changed to an intractability, since only partial information can be decodable by attackers. A new class of secret key scheme is developed in such a way.