Certificate Authority

cryptography, body (CA or "Trusted Third Party") An entity

(typically a company) that issues digital certificates to

other entities (organisations or individuals) to allow them to

prove their identity to others. A Certificate Authority might

be an external company such as VeriSign that offers digital

certificate services or they might be an internal organisation

such as a corporate MIS department. The Certificate

Authority's chief function is to verify the identity of

entities and issue digital certificates attesting to that

identity.

The process uses public key cryptography to create a

"network of trust". If I want to prove my identity to you, I

ask a CA (who you trust to have verified my identity) to

encrypt a hash of my signed key with their private key.

Then you can use the CA's public key to decrypt the hash and

compare it with a hash you calculate yourself. Hashes are

used to decrease the amount of data that needs to be

transmitted. The hash function must be cryptographicallystrong, e.g. MD5.

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(1998-03-30)