CertiGuide to Security+  9  Chapter 4:  Basics of Cryptography (Domain 4.0; 15%)

FIPS 1 4.5.1  Centralized vs. Decentralized

Key pairs and their associated certificates have a defined life cycle. They are initially requested by the individuals or entities requiring them. Typically, this request is made to a Certificate Authority (CA), which is responsible for verifying the requester’s identity and generating a key pair and certificate for them. The CA then sends those items to the requester.

The certificate is then valid for use by the requester until its expiration date, at which point the certificate is automatically revoked. Private keys are typically stored in a secure location, possibly including hardware designed expressly for this purpose. If a key is lost, your PKI may allow for its retrieval via a process known as key recovery.

It is possible to revoke a certificate prior to its expiration, for reasons including compromise of the private key, using a process known as certificate revocation, which permanently invalidates the certificate. You can also temporarily disable a certificate through certificate suspension; you might do this if you suspect key compromise but don’t know for sure yet whether it occurred. Revoked, suspended and expired certificates are placed into one or more certificate revocation notice systems such as a Certificate Revocation List (or CRL).

More information on these and other related topics is included below.

FIPS 1 4.5.1  Centralized vs. Decentralized