Cryptographic turbo code for image transmission over mobile networks

Abstract

Mobile communication has become an essential part of our daily life for accessing and sharing data over internet in addition to voice communication. Mobile communication channel is an open network and hence maintaining the confidentiality and reliability of the data has always been an area of concern. Reliability of data against channel noise can be ensured by various error correcting codes. Turbo Code (TC) is an excellent channel encoder with near Shannon limit error correction performance. However, TC does not guarantee the security of the transmitted image against intruders on the wireless channel. Proposed Cryptographic Turbo Code (CTC) is a modification of the existing TC to provide encryption and error correction as a single entity. Encryption of data is achieved by the proposed Elliptic Curve Cryptographic Interleaver (ECCI) of CTC. The ECCI is an asymmetric private key interleaver which shuffles the input bit sequence based on the Elliptic Curve (EC) arithmetic and a private key. Shuffling the bits also reduces its correlation and improves the error correction performance of the code. The CTC ensures the secrecy of the shared private keys over an insecure wireless channel by Elliptic Curve Diffie-Hellman Key Exchange (ECDHKE). This makes the CTC robust against cryptographic attacks. The qualitative and quantitative performance analysis of the proposed code is evaluated to validate its effectiveness for image transmission over a mobile network in contrast to other state-of-art methods. Simulation results illustrate a similar coding gain, Peak Signal to Noise Ratio (PSNR) and Mean Square Error (MSE) for images retrieved by the proposed CTC, encrypted TC and TC for authorized users. Additionally, it ensures security of the data from unauthorized users as compared to TC. Investigation results also depict the strength of CTC against Brute Force, known plaintext, chosen plaintext and cipher text attacks.