X509_get0_subject_key_id
if (!set_senderKID(ctx, msg, X509_get0_subject_key_id(ctx->cert)))
if (!check_kid(ctx, X509_get0_subject_key_id(cert), msg->header->senderKID))
const ASN1_OCTET_STRING *cert_keyid = X509_get0_subject_key_id(cert);
cert_keyid = X509_get0_subject_key_id(cert);
const ASN1_OCTET_STRING *X509_get0_subject_key_id(X509 *x);