invalidity date

An X.509 CRL entry extension that "indicates the date at which it is known or suspected that the [revoked certificate's private key] was compromised or that the certificate should otherwise be considered invalid." [X509].

Tutorial: This date may be earlier than the revocation date in the CRL entry, and may even be earlier than the date of issue of earlier CRLs. However, the invalidity date is not, by itself,

sufficient for purposes of non-repudiation service. For example, to fraudulently repudiate a validly generated signature, a private key holder may falsely claim that the key was compromised at some time in the past.