Security is an important issue related to the storage and communication of data and information. In data and information security, cryptography and steganography are two of the most common security techniques. On one hand, there is cryptography, which is the secret communication between two parties by message scrambling on the sender's side and message unscrambling on the receiver's side so that only the intended receiver gets the secret message. On the other hand, there is steganography, which is the hiding of information in a medium in such a way that no one other than the sender or the intended receiver realizes there is a hidden message. Successful reverse engineering of cryptography and steganography give cryptanalysis and steganalysis respectively. Cryptography and cryptanalysis constitute cryptology (or crypto) while steganography and steganalysis make up steganology (or stegano). This dissertation consists of three parts needed for a scientific study of a cryptanalysis problem. The first part lays out a comparative survey of various cryptology and steganology techniques by analyzing and comparing different methodologies using a set of predefined parameters. This part offers valuable knowledge on the state of the art techniques used on cryptanalysis. The second part proposes a new lossless synthetic stegano-crypto methodology that blends together five cryptography, steganography and compression techniques to form a single methodology for mutual information encryption and hiding in images. The methods that compose the synthetic methodology are SCAN Encryption, SCAN Compression, SCAN Steganography, Least Significant Bit (LSB) Steganography and Regional Steganography with Segmentation. The synthetic methodology plays the role of a complex and difficult technique that we have to work on in an attempt to break it by using a reverse engineering approach. In the third part, a cryptanalysis attack against the proposed synthetic stegano-crypto methodology is presented in order for the important features (weak points) related to the method to be extracted and assist in the reverse engineering process of encrypted information in images.
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