An optional secure channel can be created for authentication to ensure credentials are encrypted
when sent to the server. To implement a secure authentication channel: - Create a key pair using the com.threerings.presents.tool.KeyPairGen tool. You will need to distribute the public key with your client, and the private key with the server. - On your server during initialization, use PresentsConnectionManager.setPrivateKey to set the private key. It can take the key string gerenated by KeyPairGen. This will return true if the key was sucessfully set and the server supports the encryption necessary. - On your client before authenticating, use Client.setPublicKey to set the public key. As with setPrivateKey, it will return true if the client supports the encryption necessary. That's it! You should now be authenticating over a secure encrypted channel. The server can still accept unsecured authentication attempts (for the purpose of telling the client it needs a new version to get the server's public key). A failure to decrypt the client credientials on the server will return a new "m.failed_to_secure" authentication code. Handshake process: - The client generates a random 128-bit key, and encodes it with the public key using a 32-bit salt (PublicKeyCredentials). This is sent to the server as a SecureRequest. - The server decrypts the i128-bit key using its private key and verifies it against the salt. If verification fails, a failed secure response is returned and the client will authenticate over a clear channel. If verification succeeds, the server generates a random 128-bit AES key and encodes it with the 128-bit key sent from the client. This is sent back to the client as a SecureResponse. - The client will decode the AES key sent from the server (using the random key it generated at the start of the handshake). Using the AES key, the client will encrypt their credentials using an AESAuthRequest and send it to the server. - The server can now decrypt the credentials from the client and pass the AESAuthRequest to the configured authenticators to complete authentication. If the server fails to decrypt the credentials a "m.failed_to_secure" authentication code is returned to the client. git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@6477 542714f4-19e9-0310-aa3c-eee0fc999fb1
This commit is contained in:
Mark Johnson
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//
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// $Id$
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//
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// Narya library - tools for developing networked games
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// Copyright (C) 2002-2011 Three Rings Design, Inc., All Rights Reserved
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// http://code.google.com/p/narya/
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//
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// This library is free software; you can redistribute it and/or modify it
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// under the terms of the GNU Lesser General Public License as published
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// by the Free Software Foundation; either version 2.1 of the License, or
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// (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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package com.threerings.presents.util;
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import java.math.BigInteger;
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import java.security.GeneralSecurityException;
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import java.security.Key;
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import java.security.KeyFactory;
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import java.security.KeyPair;
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import java.security.KeyPairGenerator;
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import java.security.PrivateKey;
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import java.security.PublicKey;
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import java.security.SecureRandom;
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import java.security.spec.RSAPrivateKeySpec;
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import java.security.spec.RSAPublicKeySpec;
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import javax.crypto.Cipher;
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import javax.crypto.spec.IvParameterSpec;
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import javax.crypto.spec.SecretKeySpec;
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import static com.threerings.presents.Log.log;
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/**
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* Security utilities for performing secure authentication.
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*/
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public class SecureUtil
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{
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/**
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* Creates our AES cipher.
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*/
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public static Cipher getAESCipher(int mode, byte[] key)
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{
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try {
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Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
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SecretKeySpec aesKey = new SecretKeySpec(key, "AES");
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cipher.init(mode, aesKey, IVPS);
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return cipher;
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} catch (GeneralSecurityException gse) {
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log.warning("Failed to create cipher", gse);
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}
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return null;
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}
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/**
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* Creates our RSA cipher.
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*/
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public static Cipher getRSACipher(PrivateKey key)
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{
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return getRSACipher(Cipher.DECRYPT_MODE, key);
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}
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/**
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* Creates our RSA cipher.
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*/
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public static Cipher getRSACipher(PublicKey key)
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{
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return getRSACipher(Cipher.ENCRYPT_MODE, key);
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}
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/**
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* Creates our RSA cipher.
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*/
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public static Cipher getRSACipher(int mode, Key key)
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{
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try {
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Cipher cipher = Cipher.getInstance("RSA");
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cipher.init(mode, key);
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return cipher;
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} catch (GeneralSecurityException gse) {
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log.warning("Failed to create cipher", gse);
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}
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return null;
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}
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/**
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* Creates an RSA key pair.
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*/
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public static KeyPair genRSAKeyPair (int bits)
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{
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try {
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KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
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kpg.initialize(bits);
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return kpg.genKeyPair();
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} catch (GeneralSecurityException gse) {
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log.warning("Failed to create key pair", gse);
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}
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return null;
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}
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/**
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* Converts an key to a string suitable for a properties file.
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*/
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public static String RSAKeyToString (PublicKey key)
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{
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try {
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KeyFactory kf = KeyFactory.getInstance("RSA");
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RSAPublicKeySpec spec = kf.getKeySpec(key, RSAPublicKeySpec.class);
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StringBuilder buf = new StringBuilder();
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buf.append(spec.getModulus().toString(16))
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.append(SPLIT)
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.append(spec.getPublicExponent().toString(16));
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return buf.toString();
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} catch (GeneralSecurityException gse) {
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log.warning("Failed to convert key to string", gse);
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}
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return null;
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}
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/**
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* Converts an key to a string suitable for a properties file.
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*/
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public static String RSAKeyToString (PrivateKey key)
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{
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try {
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KeyFactory kf = KeyFactory.getInstance("RSA");
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RSAPrivateKeySpec spec = kf.getKeySpec(key, RSAPrivateKeySpec.class);
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StringBuilder buf = new StringBuilder();
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buf.append(spec.getModulus().toString(16))
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.append(SPLIT)
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.append(spec.getPrivateExponent().toString(16));
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return buf.toString();
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} catch (GeneralSecurityException gse) {
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log.warning("Failed to convert key to string", gse);
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}
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return null;
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}
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/**
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* Creates a public key from the supplied string.
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*/
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public static PublicKey stringToRSAPublicKey (String str)
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{
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try {
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BigInteger mod = new BigInteger(str.substring(0, str.indexOf(SPLIT)), 16);
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BigInteger exp = new BigInteger(str.substring(str.indexOf(SPLIT) + 1), 16);
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RSAPublicKeySpec keySpec = new RSAPublicKeySpec(mod, exp);
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KeyFactory kf = KeyFactory.getInstance("RSA");
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return kf.generatePublic(keySpec);
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} catch (NumberFormatException nfe) {
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log.warning("Failed to read key from string.", "str", str, nfe);
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} catch (GeneralSecurityException gse) {
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log.warning("Failed to read key from string.", "str", str, gse);
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}
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return null;
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}
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/**
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* Creates a private key from the supplied string.
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*/
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public static PrivateKey stringToRSAPrivateKey (String str)
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{
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try {
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BigInteger mod = new BigInteger(str.substring(0, str.indexOf(SPLIT)), 16);
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BigInteger exp = new BigInteger(str.substring(str.indexOf(SPLIT) + 1), 16);
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RSAPrivateKeySpec keySpec = new RSAPrivateKeySpec(mod, exp);
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KeyFactory kf = KeyFactory.getInstance("RSA");
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return kf.generatePrivate(keySpec);
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} catch (NumberFormatException nfe) {
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log.warning("Failed to read key from string.", "str", str, nfe);
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} catch (GeneralSecurityException gse) {
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log.warning("Failed to read key from string.", "str", str, gse);
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}
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return null;
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}
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/**
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* Returns true if we can generate our ciphers.
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*/
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public static boolean ciphersSupported (PrivateKey key)
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{
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return getRSACipher(key) != null && getAESCipher(Cipher.ENCRYPT_MODE, new byte[16]) != null;
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}
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/**
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* Returns true if we can generate our ciphers.
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*/
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public static boolean ciphersSupported (PublicKey key)
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{
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return getRSACipher(key) != null && getAESCipher(Cipher.ENCRYPT_MODE, new byte[16]) != null;
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}
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/**
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* Creates a random key.
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*/
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public static byte[] createRandomKey (int length)
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{
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byte[] secret = new byte[length];
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_rand.nextBytes(secret);
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return secret;
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}
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/**
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* Encrypts a secret key and salt with a public key.
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*/
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public static byte[] encryptBytes (PublicKey key, byte[] secret, byte[] salt)
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{
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byte[] encrypt = new byte[secret.length + salt.length];
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for (int ii = 0; ii < secret.length; ii++) {
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encrypt[ii] = secret[ii];
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}
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for (int ii = 0; ii < salt.length; ii++) {
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encrypt[secret.length + ii] = salt[ii];
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}
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try {
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return getRSACipher(key).doFinal(encrypt);
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} catch (GeneralSecurityException gse) {
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log.warning("Failed to encrypt bytes", gse);
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}
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return encrypt;
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}
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/**
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* Decrypts a secret key and checks for tailing salt.
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*
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* @return the secret key, or null on failure or non-matching salt.
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*/
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public static byte[] decryptBytes (PrivateKey key, byte[] encrypted, byte[] salt)
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{
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try {
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byte[] decrypted = getRSACipher(key).doFinal(encrypted);
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for (int ii = 0; ii < salt.length; ii++) {
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if (decrypted[decrypted.length - salt.length + ii] != salt[ii]) {
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return null;
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}
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}
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byte[] secret = new byte[decrypted.length - salt.length];
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for (int ii = 0; ii < secret.length; ii++) {
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secret[ii] = decrypted[ii];
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}
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return secret;
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} catch (GeneralSecurityException gse) {
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log.warning("Failed to dencrypt bytes", gse);
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}
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return null;
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}
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/**
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* XORs a byte array against a key.
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*/
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public static byte[] xorBytes (byte[] data, byte[] key)
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{
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byte[] xored = new byte[data.length];
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for (int ii = 0; ii < data.length; ii++) {
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xored[ii] = (byte)(data[ii] ^ key[ii % key.length]);
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}
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return xored;
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}
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protected static final SecureRandom _rand = new SecureRandom();
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/** Our split character. */
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protected static final char SPLIT = '#';
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/** Our initialization vector. */
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protected static final byte[] IV = new byte[] {
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0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
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0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08
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};
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protected static final IvParameterSpec IVPS = new IvParameterSpec(IV);
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}
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