Cryptography from Quantum mechanical viewpoint

Cryptography is an art and science of secure communication. Here the sender and receiver are guaranteed the security through encryption of their data, with the help of a common key. Both the parties should agree on this key prior to communication. The cryptographic systems which perform these tasks are designed to keep the key secret while assuming that the algorithm used for encryption and decryption is public. Thus key exchange is a very sensitive issue. In modern cryptographic algorithms this security is based on the mathematical complexity of the algorithm. But quantum computation is expected to revolutionize computing paradigm in near future. This presents a challenge amongst the researchers to develop new cryptographic techniques that can survive the quantum computing era. This paper reviews the radical use of quantum mechanics for cryptography.