OCSP_cert_to_id
id = OCSP_cert_to_id(cert_id_md, cert, issuer);
ca_id = OCSP_cert_to_id(cert_id_md, NULL, ca);
id = OCSP_cert_to_id(NULL, x, X509_OBJECT_get0_X509(obj));
OCSP_CERTID *OCSP_cert_to_id(const EVP_MD *dgst, const X509 *subject,
cid = OCSP_cert_to_id(NULL, main_cert, issuer);
cid = OCSP_cert_to_id(NULL, main_cert, X509_OBJECT_get0_X509(obj));