Cryptography: A Technique to Maintain Network Security
Cryptography is the science of writing in secret code. In data and telecommunications, cryptography is necessary when communicating over any entrusted medium, which includes just about any network, particularly the Internet. Cryptography, then, not only protects data from theft or alteration, but it can also be used for user authentication. There are, in general, three types of cryptographic schemes typically used to accomplish these goals: secret key (or symmetric) cryptography, public key (or asymmetric) cryptography, and hash functions, in all cases, the initial unencrypted data is referred to as plaintext. It is encrypted into cipher text, which will in turn (usually) be decrypted into usable plaintext.