Abstract: Cryptography is the oldest and effective way to provide security to computer networks and data. The very first cryptographic techniqueswere developed over 200 years ago. As technology grows there is an evolution in cryptographic techniques. A thorough understanding of cryptography and encryption will help people develop better ways to protect valuable information. In present scenario modern cryptographic techniques provides a better way of encryption. Algorithms like Symmetric and Asymmetric key, ECC cryptography techniques had tremendous advantages over classic techniques  but they are also having some drawbacks like security issues, hence did not provide full security to the network. The recent technique Quantum Cryptography is a solution to above problem but there are some issues regarding practical implantation of this approach. Bimolecular Computation has led to remarkable new dimension in secret communication i.e. DNA cryptography . It is a novel field technology that brings forward a new hope for unbreakable algorithms. DNA cryptography has much more storage and computing capabilities than the traditional cryptographic algorithms. This paper will build a comparison between old cryptographic algorithms and their issues and it also provides an overview of different approaches used in DNA Cryptography.
Keywords: Symmetric key cryptography (SKC), Asymmetric key cryptography (AKC), Quantum cryptography (QC), DNA cryptograph