26-11-2012, 06:11 PM
A SIMPLE MESSAGE ENCRYPTION SCHEME BASED ON AMINO ACID PROTEIN SEQUENCE
INTRODUCTION
Recently, biological techniques become more and more popular, as they are applied to many kinds of applications, authentication protocols, biochemistry, and cryptography. . Bioinformatics plays a very important role on molecular datasets. Encrypting secret data in peptide sequence or amino-acid sequence becomes an important and interesting research topic. This paper presents a simple, secure and reversible encryption scheme that converts the message into an amino-acid protein sequence to provide security.
KEY TERMS
1.Amino-acids
Amino-acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids.The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen[5]. Amino acids are critical to life, and have many functions in metabolism. One particularly important function is to serve as the building blocks of proteins, which are linear chains of amino acids. Amino acids can be linked together in varying sequences to form a vast variety of proteins. Twenty-two amino acids are naturally incorporated into polypeptides[6] and are called proteinogenic or standard amino acids
2.Cryptography
Today, network technologies have improved a lot so that more and more people access the remote facilities and send or receive various kinds of digital data over the Internet. However, the Internet is public but insecure channel to transmit data. Thus, important information must be converted into a non-readable form while delivered via the Internet such that only the authorized receiver can read it. Different methods of encryption and decryption techniques were used from ancient times. Nowadays biology techniques are proposed for encryption and decryption.
TYPES OF CRYPTOGRAPHIC ALGORITHMS
There are several ways of classifying cryptographic algorithms. For purposes
of this paper, they will be categorized based on the number of keys that are
employed for encryption and decryption, and further defined by their
application and use. The three types of algorithms are
Secret Key Cryptography (SKC): Uses a single key for both encryption
and decryption
Public Key Cryptography (PKC): Uses one key for encryption and
another for decryption
Hash Functions: Uses a mathematical transformation to irreversibly
"encrypt" information
3.Encryption
Transforms plaintext into ciphertext.
Protects the confidentiality of the message
Reverse process is decryption.
Explain the figure.
4.Bioinformatics
The term can be considered to mean information technology applied to the management and analysis of biological data; this has implications in diverse areas, ranging from artificial intelligence and robotics.
Bioinformatics is conceptualizing biology in terms of molecules (in the sense of Phy-sical chemistry) and applying “informatics techniques” (derived from disciplines such as applied mathematics, computer science and statistics) to understand and organize the information associated with these molecules, on a large scale.In short, bioinformatics is a management information system for molecular biology and has many practical applications. Also, it is often defined as the application of computational techniques to understand and organize the information associated with biological macromolecules.
ENCRYPTION ALGORITHM
From the 22-aminoacid sequence a user can always randomly select one permutation among 22!
Permutations .The present work discusses a symmetric key encryption technology using the above aminoacid sequence. The sender selects a random permutation of the above sequence as a key and generates a dynamic look-up table for encryption and decryption. As this is a symmetric key algorithm, the sender transmits the key to the receiver as this secret key that should be used for both encryption and decryption.
KEY GENERATION
1) Alice divide the above sequence into two subsets randomly.
i){A,C,D,E,F,G,H,I,K,L,M,N,O,P,Q,R,S,T,W,Y,U } and ii) { V }.
2) As Alice wants to transmit secure information to BOB, he selects a random permutation of the first subset ,
say selecting a random number in the range { 1,21!} as secret key. Say he selects the permutation
“HGFCADILNMYTSWFERPOQU”.
3) Alice also selects a random character as a second subset.
4) Alice sends the key { “HGFCADILNMYTSWFERPOQU”, “V” } to Bob.
Alice generates a look-up table that represents amino acid sequence[4] for standard ASCII character-set that range from 32 to
ENCRYPTION
Alice now represents each character in the plaintext with not more than two characters to generate the ciphertext. Since he chooses {V} as the second subset, V represents a single character representation in the ciphertext. Alice generates the ciphertext of each character by subtracting 32 from the ASCII value of the character and gets the amino-acid sequence for the character.
Decryption
The decryption process is just the reverse of the encryption process with the same key. After receiving the cipher text, Bob generates the same look-up table to decrypt the cipher. He decrypts the cipher by taking 2 characters at a time to get a plaintext character and whenever he encounters the character “V” he takes single character to get a plaintext character.
Security Analysis:
This Encryption Scheme is secured as along as the algorithm is kept secret or else this scheme is subjected to known cipher text and Brute-force attack as there 21! Permutations are to be experimented by the cryptanalyst to get the secret key.
Performance:
As the proposed algorithm is simple and based on ASCII decimal codes of the characters, the encryption and decryption times are very less.
Future Work:
The algorithm can be also used to hide or embed a text in an amino-acid sequence.
This Scheme can be made more complex to provide more security if we permit more permutations in the key-generation and encryption algorithms.