Adding support for SCEP renewals

[Stueypoo]

Describe your changes

A plug-in to provide SCEP renewal capabilities using client certificate authentication (as per the SCEP RFC (and earlier drafts).

To enable SCEP renewal, the following are required:

1. The SCEP configuration must allow 'Allow Client Certificate Renewal'
2. The End-Entity must be associated with an End Entity Profile that enables 'Allow renewal before expiration'. Also, ensure the
   'Days before expiration' is set to an appropriate number (the SCEP RFC suggests 50% of certificate validity).

Upon an incoming SCEP renewal message, this plug-in will perform a validation of the Signer's certificate before allowing the request. This validation must meet all these criteria:

1. Certificate is provided in the request.
2. Certificate is not expired or pending.
3. Certificate was previously issued to the end-entity identified in the request. By inference, this suggests that the certificate
   was issued by a trusted authority as the certificate was found in the EJBCA's database. Please note that the Signer's certificate could have been issued by a different CA to that which will perform the renewal.
4. Certificate is not revoked.

SCEP renewals using a previously issued key may be permitted by the SCEP configuration with the parameter 'Allow Client Certificate Renewal using old key'. However, be aware that if the CA setting 'Enforce key renewal' is enabled, then this will prevent the certificate being issued.

During SCEP processing (for initial certificate or for renewals), the User's password will be reset to a random value. This will invalidate the Challenge Password previously known to the Client. This is the recommendation in the RFC (and earlier drafts).

How has this been tested?

A SystemTest is included. Run this with "ant test:runweb"

Checklist before requesting a review

• I have performed a self-review of my code
• I have kept the patch limited to only change the parts related to the patch
• This change requires a documentation update

See also Contributing Guidelines.

[MalinRidelius]

Thanks, Stueypoo! A contribution of this size requires signing our Contributor Assignment Agreement. Please reach out to me Malin Ridelius at [email protected] so we can guide you, or your manager, through the process.