X509v3_KU_DIGITAL_SIGNATURE
if (X509_get_key_usage(cpk->x509) & X509v3_KU_DIGITAL_SIGNATURE)
if (!(X509_get_key_usage(x) & X509v3_KU_DIGITAL_SIGNATURE)) {
if (!(X509_get_key_usage(cpk->x509) & X509v3_KU_DIGITAL_SIGNATURE))