Читать книгу Optical Cryptosystems - Naveen K. Nishchal - Страница 13

Depending on the common uses, cryptography can be classified into two categories; symmetric key cryptography and asymmetric key cryptography. Symmetric key cryptography is a classical encryption method. It is referred to as a situation in which the key used for encryption is as used for decryption. In this case, key distribution must be performed prior to data transfer. Therefore, the security key plays a highly significant role because security directly depends on the nature of the key. Asymmetric key cryptography is an advanced encryption method. It is referred to as a situation in which the key used for encryption is different than the key used for decryption. In this case, a pair of keys, public and private keys, are used. The security is very high compared to the classical method of encryption.

Of late, hash functions are also considered as a type of cryptography, which establishes the authenticity of the user [7].