A Technique for DNA Cryptography Based on Dynamic Mechanisms

Abstract

This thesis proposes a dynamic technique for DNA cryptography based on dynamic sequence table and dynamic DNA encoding mechanisms along with an asymmetric cryptosystem. The main focusing area of the thesis is to deploy a completely dynamic approach which includes generating dynamic sequence table to produce ciphertext, dividing the ciphertext into a number of chunks, applying public key to encrypt each chunk and finally dynamic DNA encoding is used to merge the chunk of each ciphertext. Firstly, the plaintext is transformed into its corresponding DNA bases. Secondly, ASCII characters are randomly assigned to each sequence of DNA bases in the dynamic sequence table. Herein, the position of the DNA bases changes dynamically through iteration process. The generated ciphertext is divided into a fixed sized of chunks and to encrypt each chunk an symmetric cryptosystem is employed. Dynamic DNA encoding is formed using adequate random strings and efficient mathematical series and it is used to set how much random strings will be taken to merge all the ciphertext of chunks together. The usage of dynamic sequence table, public key cryptography, random string and dynamic DNA encoding altogether enhance the secrecy of data. According to the National Institute of Standards and Technology (NIST), an empirical test is performed to analyze the randomness of the ciphertext. Finally the encryption and decryption time is compared between the proposed technique and other existing techniques.