# Certificate validation

RSE daemon starts certificate processing by validating the certificate. Some key aspects that are checked are the dates the certificate is valid and the trust-worthiness of the Certificate Authority (CA) used to sign the certificate. Optionally, a (third party) Certificate Revocation List (CRL) can be consulted also. After this validation, the certificate is processed for the authentication step, as described in Certificate authentication.

RSE daemon uses z/OS System SSL services to validate the certificate. Therefore, ensure that `SYS1.SIEALNKE` is accessible by the RSE daemon, either via LPA, LINKLIST or via the STEPLIB directive in `rsed.envvars`.

Also ensure that `ssl.properties` is set up correctly (SSL must be enabled), as described in the Rational Developer for System z Host Configuration Guide (SC23-7658).

- Developer for System z v7510 maintenance note
- Certificate Authority (CA) validation
- (Optional) Query a Certificate Revocation List (CRL)

Parent topic: Enhanced client authentication support