The mathematical science used to secure the confidentiality, integrity, authentication, and non-repudiation of messages by use of codes, ciphers and cryptograms. Also the act or art of writing in codes or ciphers. It is the pursuit of four particular goals:

The message can only be understood by the designated recipient.
No undetected alteration of the message in transit or storage is possible.
The sender and the recipient of the message can verify each other's identity.
The sender cannot disclaim his/her intentions in the creation or transmission of the message.

Procedures and protocols used to achieve (some of) these goals are known as cryptosystems.

Cryptography is divided largely into ConventionalCryptography and PublicKey cryptography.

See also:

Part of CategoryCryptography