The readme mentions keeping a database of revoked certificates. Would you instead be interested in a pull request that uses crlDistributionPoints CRL and / or authorityInfoAccess OCSP to determine if a certificate is revoked? These are available as an array of X509::Certificate.extensions and as far as I am aware any issued certificate by a CA will include these extensions on their certificates and could be used to validate a certificate by performing CRL / OCSP request at the time of validation. Some CRLs can get large 10MB+ so OCSP should probably be preferred when the certificate provides authorityInfoAccess.