This identifies a signature containing the SHA256 hash of an X.509 certificate's
To-Be-Signed contents, and a time of revocation. The SignatureHeader size shall
always be 0. The SignatureSize shall always be 16 (size of the SignatureOwner component)
+ 48 bytes for an EFI_CERT_X509_SHA256 structure. If the TimeOfRevocation is non-zero,
the certificate should be considered to be revoked from that time and onwards, and
otherwise the certificate shall be considered to always be revoked.
This identifies a signature containing the SHA256 hash of an X.509 certificate's To-Be-Signed contents, and a time of revocation. The SignatureHeader size shall always be 0. The SignatureSize shall always be 16 (size of the SignatureOwner component) + 48 bytes for an EFI_CERT_X509_SHA256 structure. If the TimeOfRevocation is non-zero, the certificate should be considered to be revoked from that time and onwards, and otherwise the certificate shall be considered to always be revoked.