A Comparative Survey on Cryptology-Based Methodologies

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. Cryptography and cryptanalysis constitute cryptology (or crypto) while steganography and steganalysis make up steganology (or stegano). This paper presents a comparative survey of various cryptology and steganology techniques by analyzing and comparing different methodologies using a set of predefined parameters. It also offers to the reader valuable knowledge on the state of the art techniques used on cryptanalysis. DOI: 10.4018/jisp.2012070101 2 International Journal of Information Security and Privacy, 6(3), 1-37, July-September 2012 Copyright © 2012, IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global is prohibited. Basic Cryptology Concepts Cryptography is the process where an individual or party sends a message to another individual or party in a scrambled unintelligible manner such that only the intended party will get the scrambled message, which will be unscrambled to get the original message. The reverse engineering of cryptography is known as cryptanalysis. Cryptography and cryptanalysis together constitute cryptology. A cryptography system is known as a cryptosystem, or a cipher. Any cryptosystem must have a sender, plaintext, an enciphering (encrypting) function, an enciphering (encrypting) key, an algorithm, ciphertext, a transmission medium, a decrypting (deciphering) function, a decrypting (deciphering) key and a receiver (Figure 1). Plaintext is the original intelligible message a sender sends to the receiver. In order to scramble the plaintext to make it unintelligible to the potential attacker, an algorithm, along with a key, maps the plaintext to the unintelligible message known as ciphertext. This plaintext to ciphertext scrambling is known as enciphering. An algorithm is a mathematical function that maps one message to another message. A key is a variable that gives a unique output map when used with an algorithm. In enciphering, the function is referred to as an enciphering function and the key is referred to as an enciphering key. After encryption, the ciphertext is sent through a transmission medium to the receiver. When a receiver receives the ciphertext, he reverses the encryption to get the original plaintext. This reversing is referred to as deciphering. A deciphering function and a deciphering key are synonymous to their corresponding counterparts in encryption.