Cryptography

The discipline that embodies the principles, means, and methods for the transformation of data in order to hide their semantic content, prevent their unauthorized use, or prevent their undetected modification.
SOURCE: SP 800-59

The discipline that embodies principles, means, and methods for providing information security, including confidentiality, data integrity, non-repudiation, and authenticity.
SOURCE: SP 800-21

Is categorized as either secret key or public key. Secret key cryptography is based on the use of a single cryptographic key shared between two parties. The same key is used to encrypt and decrypt data. This key is kept secret by the two parties. Public key cryptography is a form of cryptography which makes use of two keys: a public key and a private key. The two keys are related but have the property that, given the public key, it is computationally infeasible to derive the private key [FIPS 140-1]. In a public key cryptosystem, each party has its own public/private key pair. The public key can be known by anyone; the private key is kept secret.
SOURCE: FIPS 191

Art or science concerning the principles, means, and methods for rendering plain information unintelligible and for restoring encrypted information to intelligible form.
SOURCE: CNSSI-4009