public void checkServerTrusted(X509Certificate[] chain, String authType) throws CertificateException {
        if (chain == null) {
            throw new IllegalArgumentException(
                    "checkServerTrusted: X509Certificate array is null");
        }
        if (!(chain.length > 0)) {
            throw new IllegalArgumentException(
                    "checkServerTrusted: X509Certificate is empty");
        }

        // Perform customary SSL/TLS checks
        TrustManagerFactory tmf;
        try {
            tmf = TrustManagerFactory.getInstance("X509");
            tmf.init((KeyStore) null);

            for (TrustManager trustManager : tmf.getTrustManagers()) {
                ((X509TrustManager) trustManager).checkServerTrusted(
                        chain, authType);
            }

        } catch (Exception e) {
            throw new CertificateException(e.toString());
        }

        // Hack ahead: BigInteger and toString(). We know a DER encoded Public
        // Key starts with 0x30 (ASN.1 SEQUENCE and CONSTRUCTED), so there is
        // no leading 0x00 to drop.
        RSAPublicKey pubkey = (RSAPublicKey) chain[0].getPublicKey();
//        String encoded = new BigInteger(1 /* positive */, pubkey.getEncoded())
//                .toString(16);
        String encoded = null;
        try {
            encoded = new String(Base64.encode(pubkey.getEncoded(), Base64.DEFAULT),"UTF-8");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }


        // Pin it!
        final boolean expected = publicKey.equalsIgnoreCase(encoded);
        // fail if expected public key is different from our public key
        if (!expected) {
            throw new CertificateException(
                    "Not trusted");
        }
    }