Key History refers to:

• A. An archive of certificate information that allows older keys to be used
• B. A log of all key revocations
• C. A policy for key rotation
• D. A real-time key generation service

Answer: (A)

Key History is the archive of information about previously issued keys and certificates, kept so that data signed or encrypted with older keys can still be verified or decrypted after those keys have been rotated or retired. This history links old key identifiers to their actual key material and validity periods, enabling long-term validation of past communications and records. It helps maintain trust across the life of a PKI by ensuring that signatures made with earlier keys remain verifiable and that historical data remains accessible. This concept is different from keeping a log of revocations, which tracks why a key is no longer trusted, from a policy that governs how keys should be rotated, or from a real-time key generation service that creates new keys on demand.