certification path

A linked sequence of one or more public-key certificates, or one or more public-key certificates and one attribute certificate, that enables a certificate user to verify the signature on the last certificate in the path, and thus enables the user to obtain (from that last certificate) a certified public key, or certified attributes, of the system entity that is the subject of that last certificate. (See: trust anchor, certificate validation, valid certificate.)

"An ordered sequence of certificates of objects in the [X.500 Directory Information Tree] which, together with the public key of the initial object in the path, can be processed to obtain that of the final object in the path." [R3647, X509]

Tutorial: The list is "linked" in the sense that the digital signature of each certificate (except possibly the first) is verified by the public key contained in the preceding certificate; i.e., the private key used to sign a certificate and the public key contained in the preceding certificate form a key pair that has previously been bound to the authority that signed.

The path is the "list of certificates needed to [enable] a particular user to obtain the public key [or attributes] of another [user]." [X509] Here, the word "particular" points out that a certification path that can be validated by one certificate user might not be able to be validated by another. That is because either the first certificate needs to be a trusted certificate or the signature on the first certificate needs to be verifiable by a trusted key (e.g., a root key), but such trust is established only

relative to a "particular" (i.e., specific) user, not absolutely for all users.