CRC Press eBooks
- Quantum Cryptography
S. Rajasekar, R. Velusamy
Abstract
Users of communication channels wish to have their transactions secured. Therefore, it is necessary to develop techniques which can ensure that eavesdroppers cannot intercept the messages transmitted. The technology concerned with the secure communication of data is termed as cryptography [1-3]. It is the art of hiding information in the form of a string of bits to an unauthorized party. To achieve this goal, in a classical cryptography system the message bits are combined with random bits of equal length called a key. The combined data is known as cryptogram. This technique is called encryption. A key can be public or private. The public key is to encode plaintext, while the private key is for decoding the previously encoded plaintext or cryptogram. The cryptogram is generally sent through the communication channel. Because of the randomness of the key the encoded message is completely random. Consequently, the message is untraceable to an eavesdropper. The safety of the transmission completely depends on the safety of the key. Therefore, the key should be kept secret by the users.