CA - See certifying authority.

CAPI - Cryptographic Application Programming Interface.

Capstone - The U.S. government's project to develop a set of standards for publicly available cryptography, as authorized by the Computer Security Act of 1987. See Clipper, DSA, DSS, and Skipjack.

certificate - In cryptography, an electronic document binding some pieces of information together, such as a user's identity and public key. Certifying Authorities (CA's) provide certificates.

certificate revocation list - A list of certificates that have been revoked before their expiration date.

Certifying Authority (CA) - A person or organization that creates certificates.

checksum - Used in error detection, a checksum is a computation done on the message and transmitted with the message; similar to using parity bits.

chosen ciphertext attack - An attack where the cryptanalyst may choose the ciphertext to be decrypted.

chosen plaintext attack - A form of cryptanalysis where the cryptanalyst may choose the plaintext to be encrypted.

cipher - An encryption - decryption algorithm.

ciphertext - Encrypted data.

ciphertext-only attack - A form of cryptanalysis where the cryptanalyst has some ciphertext but nothing else.

Clipper - Clipper is an encryption chip developed and sponsored by the U.S. government as part of the Capstone project.

compression function - A function that takes a fixed length input and returns a shorter, fixed length output. See also hash functions.

compromise - The united disclosure or discovery of a cryptographic key or secret.

concatenate - To place two (or more) things together one directly after the other. For example, treehouse is the concatenation of the words tree and house.

covert channel - A hidden communication medium. See also subliminal channel.

CRL - Certificate Revocation List.

cryptanalysis - The art and science of breaking encryption or any form of cryptography. See attack.

cryptography - The art and science of using mathematics to secure information and create a high degree of trust in the electronic realm. See also public-key, symmetric-key, and threshold cryptography.

cryptology - The branch of mathematics concerned with cryptography and cryptanalysis.

cryptosystem - An encryption decryption algorithm (cipher), together with all possible plaintexts, ciphertexts and keys.