Specifying an OCSP Signature Certificate Authority List

OCSP signing certificate trust is established by matching a signing certificate with a local configuration of the OCSP signing authority in question. This option is specified in Section 4.2.2.2 Authorized Responders of RFC 2560, X.509 Internet Public Key Infrastructure Online Certificate Status Protocol - OCSP, as a way of verifying that the entity which issued the OCSP signing certificate is actually authorized to sign a particular certificate‘s OCSP response message. The OCSP CA list is only required for TRM; it is not used for DTM and common issuer.

The specified PKI certificate list is configured using the set pki certificate command. This list must contain the expected OCSP Response signing certificate. Additionally, this certificate must contain a trusted use extension which permits OCSP signing.

A “trusted use extension” can be appended to a certificate using OpenSSL. The following example appends a trusted use extension specifying an original file and the trusted file: ocsp-sig-ca.pem is the original certificate file and the output file trusted-ocsp-sig-ca.pem is the trusted file:

% openssl x509 -in ocsp-sig-ca.pem -addtrust OCSPSigning -out trusted-ocsp-sig-ca.pem

What follows is an example of an original certificate followed by the openssl command output trusted certificate with the modifications to the original certificate bolded:

-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
-----BEGIN TRUSTED CERTIFICATE-----
MIICgTCCAeqgAwIBAgIJAMng4JQ0MOeIMA0GCSqGSIb3DQEBBQUAMGAxCzAJBgNV
BAYTAlVTMRIwEAYDVQQKEwlFbnRlcmFzeXMxDDAKBgNVBAsTA0RvRDEMMAoGA1UE
CxMDUEtJMSEwHwYDVQQDExhFc3lzIEpJVEMgT0NTUCBSZXNwb25kZXIwHhcNMTIw
MjE3MTg0MzEwWhcNMjIwMjE0MTg0MzEwWjBgMQswCQYDVQQGEwJVUzESMBAGA1UE
ChMJRW50ZXJhc3lzMQwwCgYDVQQLEwNEb0QxDDAKBgNVBAsTA1BLSTEhMB8GA1UE
AxMYRXN5cyBKSVRDIE9DU1AgUmVzcG9uZGVyMIGfMA0GCSqGSIb3DQEBAQUAA4GN
ADCBiQKBgQCuyC9QHBpP/n6aOS+Cx0mbgsQTS1LAUUCwxjvJdILGVfdjFB8PKG+o
W4jm7FKuRHR7uzBvAFzD9DbVkziHl2yIsy4SeiSBTQpNvHPjvUcec3rTlw7saiTw
B+CTqEm1pxcEdRKTvawK2k1ujHML1MABP2CA3SEptO+Ude4UkXMBywIDAQABo0Mw
QTAdBgNVHQ4EFgQUYFhsLiklZh0riJ1Hg7d4HPcLlBUwCwYDVR0PBAQDAgGGMBMG
A1UdJQQMMAoGCCsGAQUFBwMJMA0GCSqGSIb3DQEBBQUAA4GBADU4aQ6f8pHWLd7z
vZ8pJ8e8UCvKok1LmdXbax5TBonyyLmb7AjLrOWjZ7LKSufJL1KOBsetd5Q49LFK
h70V2fRWpGNQszpAV60WfidkNvQ0koZczEjYRQOCtMDUqxMHxsMv2MLEVE9QuGLt
+NWjeeF03E1DT3C4mnbVsTyWPZijMAwwCgYIKwYBBQUHAwk=
-----END TRUSTED CERTIFICATE-----

Trusted certificates are added to a PKI certificate list the same as any other certificate using the set pki certificate command.

Use the set pki oscp signature-ca-list command to specify a list of trusted CA certificates used to verify OCSP response signatures.