Joint Encryption and Error Correction for Steganography

Abstract

Steganography is a technique to communicate secret data by embedding it in an appropriate multimedia carrier such as image, audio, and video files. Embedding is achieved at the cost of modifying some of the bits of the cover media. High amount of embedding distorts the cover media, making it evident to an attacker. It also results in a permanent loss of the modified bits in the cover media. Reversible Data Hiding (RDH) scheme is a steganography scheme which recovers all the modified bits and the exact cover media. However, the existing schemes embed the location map of the modified bits within the cover media which reduces the embedding capacity for the secret data. In contrast to steganography, encryption protects the secret data by converting it into a meaningless and distorted message. Though, encryption and data hiding secure the secret data over an insecure communication channel, it is still vulnerable to channel noise. Thus, it is essential to provide reliability to the transmitted data in addition to its security. newlineConventional systems, deploy error correction codes for the reliability of the transmitted data against channel noise. Turbo code is an excellent error correction code. However, it does not provide security to the transmitted data. An encryption algorithm along with turbo code provides security and reliability at the cost of reduced error correction performance. Also, the scrambled appearance of the encrypted secret data makes it vulnerable to security attacks. A combination of steganography, encryption and error correction code improves the security and reliability of the secret data. However, the three-step process increases the computational cost of the overall system. Moreover, transmission of the location map of modified bits of cover image for exact recovery of the cover media reduces the embedding capacity. This thesis proposes a Modified Cryptographic Turbo Code (MCTC) to provide improved security and reliability to the secret data.