private static void checkSignatureAlgorithm(
            X509Certificate cert) throws CertificateException {
        String oid = cert.getSigAlgOID();
        for (String blacklisted : SIGNATURE_ALGORITHM_OID_BLACKLIST) {
            if (oid.equals(blacklisted)) {
                throw new CertificateException("Signature uses an insecure hash function: " + oid);
            }
        }
    }
Analyzes the cryptographic strength of a chain of X.509 certificates.
common/src/main/java/org/conscrypt/ChainStrengthAnalyzer.java