/* * Copyright (c) 1996, 2012, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package sun.security.ssl; import java.io.*; import java.security.*; import java.security.interfaces.*; import javax.crypto.*; import javax.crypto.spec.*; import javax.net.ssl.*; import sun.security.internal.spec.TlsRsaPremasterSecretParameterSpec; import sun.security.util.KeyUtil; /** * This is the client key exchange message (CLIENT --> SERVER) used with * all RSA key exchanges; it holds the RSA-encrypted pre-master secret. * * The message is encrypted using PKCS #1 block type 02 encryption with the * server's public key. The padding and resulting message size is a function * of this server's public key modulus size, but the pre-master secret is * always exactly 48 bytes. * */ final class RSAClientKeyExchange extends HandshakeMessage { /** * The TLS spec says that the version in the RSA premaster secret must * be the maximum version supported by the client (i.e. the version it * requested in its client hello version). However, we (and other * implementations) used to send the active negotiated version. The * system property below allows to toggle the behavior. */ private final static String PROP_NAME = "com.sun.net.ssl.rsaPreMasterSecretFix"; /* * Default is "false" (old behavior) for compatibility reasons in * SSLv3/TLSv1. Later protocols (TLSv1.1+) do not use this property. */ private final static boolean rsaPreMasterSecretFix = Debug.getBooleanProperty(PROP_NAME, false); /* * The following field values were encrypted with the server's public * key (or temp key from server key exchange msg) and are presented * here in DECRYPTED form. */ private ProtocolVersion protocolVersion; // preMaster [0,1] SecretKey preMaster; private byte[] encrypted; // same size as public modulus /* * Client randomly creates a pre-master secret and encrypts it * using the server's RSA public key; only the server can decrypt * it, using its RSA private key. Result is the same size as the * server's public key, and uses PKCS #1 block format 02. */ RSAClientKeyExchange(ProtocolVersion protocolVersion, ProtocolVersion maxVersion, SecureRandom generator, PublicKey publicKey) throws IOException { if (publicKey.getAlgorithm().equals("RSA") == false) { throw new SSLKeyException("Public key not of type RSA"); } this.protocolVersion = protocolVersion; int major, minor; if (rsaPreMasterSecretFix || maxVersion.v >= ProtocolVersion.TLS11.v) { major = maxVersion.major; minor = maxVersion.minor; } else { major = protocolVersion.major; minor = protocolVersion.minor; } try { String s = ((protocolVersion.v >= ProtocolVersion.TLS12.v) ? "SunTls12RsaPremasterSecret" : "SunTlsRsaPremasterSecret"); KeyGenerator kg = JsseJce.getKeyGenerator(s); kg.init(new TlsRsaPremasterSecretParameterSpec(major, minor), generator); preMaster = kg.generateKey(); Cipher cipher = JsseJce.getCipher(JsseJce.CIPHER_RSA_PKCS1); cipher.init(Cipher.WRAP_MODE, publicKey, generator); encrypted = cipher.wrap(preMaster); } catch (GeneralSecurityException e) { throw (SSLKeyException)new SSLKeyException ("RSA premaster secret error").initCause(e); } } /* * Server gets the PKCS #1 (block format 02) data, decrypts * it with its private key. */ RSAClientKeyExchange(ProtocolVersion currentVersion, ProtocolVersion maxVersion, SecureRandom generator, HandshakeInStream input, int messageSize, PrivateKey privateKey) throws IOException { if (privateKey.getAlgorithm().equals("RSA") == false) { throw new SSLKeyException("Private key not of type RSA"); } if (currentVersion.v >= ProtocolVersion.TLS10.v) { encrypted = input.getBytes16(); } else { encrypted = new byte [messageSize]; if (input.read(encrypted) != messageSize) { throw new SSLProtocolException ("SSL: read PreMasterSecret: short read"); } } try { Cipher cipher = JsseJce.getCipher(JsseJce.CIPHER_RSA_PKCS1); cipher.init(Cipher.UNWRAP_MODE, privateKey); preMaster = (SecretKey)cipher.unwrap(encrypted, "TlsRsaPremasterSecret", Cipher.SECRET_KEY); // polish the premaster secret preMaster = polishPreMasterSecretKey(currentVersion, maxVersion, generator, preMaster, null); } catch (Exception e) { // polish the premaster secret preMaster = polishPreMasterSecretKey(currentVersion, maxVersion, generator, null, e); } } /** * To avoid vulnerabilities described by section 7.4.7.1, RFC 5246, * treating incorrectly formatted message blocks and/or mismatched * version numbers in a manner indistinguishable from correctly * formatted RSA blocks. * * RFC 5246 describes the approach as : * * 1. Generate a string R of 46 random bytes * * 2. Decrypt the message to recover the plaintext M * * 3. If the PKCS#1 padding is not correct, or the length of message * M is not exactly 48 bytes: * pre_master_secret = ClientHello.client_version || R * else If ClientHello.client_version <= TLS 1.0, and version * number check is explicitly disabled: * pre_master_secret = M * else: * pre_master_secret = ClientHello.client_version || M[2..47] */ private SecretKey polishPreMasterSecretKey(ProtocolVersion currentVersion, ProtocolVersion clientHelloVersion, SecureRandom generator, SecretKey secretKey, Exception failoverException) { this.protocolVersion = clientHelloVersion; if (failoverException == null && secretKey != null) { // check the length byte[] encoded = secretKey.getEncoded(); if (encoded == null) { // unable to get the encoded key if (debug != null && Debug.isOn("handshake")) { System.out.println( "unable to get the plaintext of the premaster secret"); } int keySize = KeyUtil.getKeySize(secretKey); if (keySize > 0 && keySize != 384) { // 384 = 48 * 8 if (debug != null && Debug.isOn("handshake")) { System.out.println( "incorrect length of premaster secret: " + (keySize/8)); } return generateDummySecret(clientHelloVersion); } // The key size is exactly 48 bytes or not accessible. // // Conservatively, pass the checking to master secret // calculation. return secretKey; } else if (encoded.length == 48) { // check the version if (clientHelloVersion.major == encoded[0] && clientHelloVersion.minor == encoded[1]) { return secretKey; } else if (clientHelloVersion.v <= ProtocolVersion.TLS10.v && currentVersion.major == encoded[0] && currentVersion.minor == encoded[1]) { /* * For compatibility, we maintain the behavior that the * version in pre_master_secret can be the negotiated * version for TLS v1.0 and SSL v3.0. */ this.protocolVersion = currentVersion; return secretKey; } if (debug != null && Debug.isOn("handshake")) { System.out.println("Mismatching Protocol Versions, " + "ClientHello.client_version is " + clientHelloVersion + ", while PreMasterSecret.client_version is " + ProtocolVersion.valueOf(encoded[0], encoded[1])); } return generateDummySecret(clientHelloVersion); } else { if (debug != null && Debug.isOn("handshake")) { System.out.println( "incorrect length of premaster secret: " + encoded.length); } return generateDummySecret(clientHelloVersion); } } if (debug != null && Debug.isOn("handshake") && failoverException != null) { System.out.println("Error decrypting premaster secret:"); failoverException.printStackTrace(System.out); } return generateDummySecret(clientHelloVersion); } // generate a premaster secret with the specified version number static SecretKey generateDummySecret(ProtocolVersion version) { if (debug != null && Debug.isOn("handshake")) { System.out.println("Generating a random fake premaster secret"); } try { String s = ((version.v >= ProtocolVersion.TLS12.v) ? "SunTls12RsaPremasterSecret" : "SunTlsRsaPremasterSecret"); KeyGenerator kg = JsseJce.getKeyGenerator(s); kg.init(new TlsRsaPremasterSecretParameterSpec (version.major, version.minor)); return kg.generateKey(); } catch (GeneralSecurityException e) { throw new RuntimeException("Could not generate dummy secret", e); } } @Override int messageType() { return ht_client_key_exchange; } @Override int messageLength() { if (protocolVersion.v >= ProtocolVersion.TLS10.v) { return encrypted.length + 2; } else { return encrypted.length; } } @Override void send(HandshakeOutStream s) throws IOException { if (protocolVersion.v >= ProtocolVersion.TLS10.v) { s.putBytes16(encrypted); } else { s.write(encrypted); } } @Override void print(PrintStream s) throws IOException { s.println("*** ClientKeyExchange, RSA PreMasterSecret, " + protocolVersion); } }