alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Java example source code file (FingerprintTrustManagerFactory.java)

This example Java source code file (FingerprintTrustManagerFactory.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

certificateexception, fastthreadlocal, fingerprinttrustmanagerfactory, illegalargumentexception, list, messagedigest, net, nullpointerexception, override, pattern, regex, security, sha1, sha1_byte_len, sha1_hex_len, ssl, string, util, x509certificate

The FingerprintTrustManagerFactory.java Java example source code

/*
 * Copyright 2014 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */

package io.netty.handler.ssl.util;

import io.netty.buffer.ByteBufUtil;
import io.netty.buffer.Unpooled;
import io.netty.util.internal.EmptyArrays;
import io.netty.util.concurrent.FastThreadLocal;
import io.netty.util.internal.InternalThreadLocalMap;

import javax.net.ssl.ManagerFactoryParameters;
import javax.net.ssl.TrustManager;
import javax.net.ssl.TrustManagerFactory;
import javax.net.ssl.X509TrustManager;
import java.security.KeyStore;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.cert.CertificateEncodingException;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import java.util.Arrays;
import java.util.List;
import java.util.regex.Pattern;

/**
 * An {@link TrustManagerFactory} that trusts an X.509 certificate whose SHA1 checksum matches.
 * <p>
 * <strong>NOTE: It is recommended to verify certificates and their chain to prevent
 * <a href="https://en.wikipedia.org/wiki/Man-in-the-middle_attack">Man-in-the-middle attacks.
 * This {@link TrustManagerFactory} will <strong>only verify that the fingerprint of certificates match one
 * of the given fingerprints. This procedure is called
 * <a href="https://en.wikipedia.org/wiki/Transport_Layer_Security#Certificate_pinning">certificate pinning and
 * is an effective protection. For maximum security one should verify that the whole certificate chain is as expected.
 * It is worth mentioning that certain firewalls, proxies or other appliances found in corporate environments,
 * actually perform Man-in-the-middle attacks and thus present a different certificate fingerprint.
 * </p>
 * <p>
 * The SHA1 checksum of an X.509 certificate is calculated from its DER encoded format.  You can get the fingerprint of
 * an X.509 certificate using the {@code openssl} command.  For example:
 *
 * <pre>
 * $ openssl x509 -fingerprint -sha1 -in my_certificate.crt
 * SHA1 Fingerprint=4E:85:10:55:BC:7B:12:08:D1:EA:0A:12:C9:72:EE:F3:AA:B2:C7:CB
 * -----BEGIN CERTIFICATE-----
 * MIIBqjCCAROgAwIBAgIJALiT3Nvp0kvmMA0GCSqGSIb3DQEBBQUAMBYxFDASBgNV
 * BAMTC2V4YW1wbGUuY29tMCAXDTcwMDEwMTAwMDAwMFoYDzk5OTkxMjMxMjM1OTU5
 * WjAWMRQwEgYDVQQDEwtleGFtcGxlLmNvbTCBnzANBgkqhkiG9w0BAQEFAAOBjQAw
 * gYkCgYEAnadvODG0QCiHhaFZlLHtr5gLIkDQS8ErZ//KfqeCHTC/KJsl3xYFk0zG
 * aCv2FcmkOlokm77qV8qOW2DZdND7WuYzX6nLVuLb+GYxZ7b45iMAbAajvGh8jc9U
 * o07fUIahGqTDAIAGCWsoLUOQ9nMzO/8GRHcXJAeQ2MGY2VpCcv0CAwEAATANBgkq
 * hkiG9w0BAQUFAAOBgQBpRCnmjmNM0D7yrpkUJpBTNiqinhKLbeOvPWm+YmdInUUs
 * LoMu0mZ1IANemLwqbwJJ76fknngeB+YuVAj46SurvVCV6ekwHcbgpW1u063IRwKk
 * tQhOBO0HQxldUS4+4MYv/kuvnKkbjfgh5qfWw89Kx4kD+cycpP4yPtgDGk8ZMA==
 * -----END CERTIFICATE-----
 * </pre>
 * </p>
 */
public final class FingerprintTrustManagerFactory extends SimpleTrustManagerFactory {

    private static final Pattern FINGERPRINT_PATTERN = Pattern.compile("^[0-9a-fA-F:]+$");
    private static final Pattern FINGERPRINT_STRIP_PATTERN = Pattern.compile(":");
    private static final int SHA1_BYTE_LEN = 20;
    private static final int SHA1_HEX_LEN = SHA1_BYTE_LEN * 2;

    private static final FastThreadLocal<MessageDigest> tlmd = new FastThreadLocal() {
        @Override
        protected MessageDigest initialValue() {
            try {
                return MessageDigest.getInstance("SHA1");
            } catch (NoSuchAlgorithmException e) {
                // All Java implementation must have SHA1 digest algorithm.
                throw new Error(e);
            }
        }
    };

    private final TrustManager tm = new X509TrustManager() {

        @Override
        public void checkClientTrusted(X509Certificate[] chain, String s) throws CertificateException {
            checkTrusted("client", chain);
        }

        @Override
        public void checkServerTrusted(X509Certificate[] chain, String s) throws CertificateException {
            checkTrusted("server", chain);
        }

        private void checkTrusted(String type, X509Certificate[] chain) throws CertificateException {
            X509Certificate cert = chain[0];
            byte[] fingerprint = fingerprint(cert);
            boolean found = false;
            for (byte[] allowedFingerprint: fingerprints) {
                if (Arrays.equals(fingerprint, allowedFingerprint)) {
                    found = true;
                    break;
                }
            }

            if (!found) {
                throw new CertificateException(
                        type + " certificate with unknown fingerprint: " + cert.getSubjectDN());
            }
        }

        private byte[] fingerprint(X509Certificate cert) throws CertificateEncodingException {
            MessageDigest md = tlmd.get();
            md.reset();
            return md.digest(cert.getEncoded());
        }

        @Override
        public X509Certificate[] getAcceptedIssuers() {
            return EmptyArrays.EMPTY_X509_CERTIFICATES;
        }
    };

    private final byte[][] fingerprints;

    /**
     * Creates a new instance.
     *
     * @param fingerprints a list of SHA1 fingerprints in heaxdecimal form
     */
    public FingerprintTrustManagerFactory(Iterable<String> fingerprints) {
        this(toFingerprintArray(fingerprints));
    }

    /**
     * Creates a new instance.
     *
     * @param fingerprints a list of SHA1 fingerprints in heaxdecimal form
     */
    public FingerprintTrustManagerFactory(String... fingerprints) {
        this(toFingerprintArray(Arrays.asList(fingerprints)));
    }

    /**
     * Creates a new instance.
     *
     * @param fingerprints a list of SHA1 fingerprints
     */
    public FingerprintTrustManagerFactory(byte[]... fingerprints) {
        if (fingerprints == null) {
            throw new NullPointerException("fingerprints");
        }

        List<byte[]> list = InternalThreadLocalMap.get().arrayList();
        for (byte[] f: fingerprints) {
            if (f == null) {
                break;
            }
            if (f.length != SHA1_BYTE_LEN) {
                throw new IllegalArgumentException("malformed fingerprint: " +
                        ByteBufUtil.hexDump(Unpooled.wrappedBuffer(f)) + " (expected: SHA1)");
            }
            list.add(f.clone());
        }

        this.fingerprints = list.toArray(new byte[list.size()][]);
    }

    private static byte[][] toFingerprintArray(Iterable<String> fingerprints) {
        if (fingerprints == null) {
            throw new NullPointerException("fingerprints");
        }

        List<byte[]> list = InternalThreadLocalMap.get().arrayList();
        for (String f: fingerprints) {
            if (f == null) {
                break;
            }

            if (!FINGERPRINT_PATTERN.matcher(f).matches()) {
                throw new IllegalArgumentException("malformed fingerprint: " + f);
            }
            f = FINGERPRINT_STRIP_PATTERN.matcher(f).replaceAll("");
            if (f.length() != SHA1_HEX_LEN) {
                throw new IllegalArgumentException("malformed fingerprint: " + f + " (expected: SHA1)");
            }

            byte[] farr = new byte[SHA1_BYTE_LEN];
            for (int i = 0; i < farr.length; i ++) {
                int strIdx = i << 1;
                farr[i] = (byte) Integer.parseInt(f.substring(strIdx, strIdx + 2), 16);
            }
            list.add(farr);
        }

        return list.toArray(new byte[list.size()][]);
    }

    @Override
    protected void engineInit(KeyStore keyStore) throws Exception { }

    @Override
    protected void engineInit(ManagerFactoryParameters managerFactoryParameters) throws Exception { }

    @Override
    protected TrustManager[] engineGetTrustManagers() {
        return new TrustManager[] { tm };
    }
}

Other Java examples (source code examples)

Here is a short list of links related to this Java FingerprintTrustManagerFactory.java source code file:

... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.