/*
* 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.KeyLength;
/**
* 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.
*
* Default is "false" (old behavior) for compatibility reasons. This
* will be changed in the future.
*/
private final static String PROP_NAME =
"com.sun.net.ssl.rsaPreMasterSecretFix";
private final static boolean rsaPreMasterSecretFix =
Debug.getBooleanProperty(PROP_NAME, false);
int messageType() {
return ht_client_key_exchange;
}
/*
* 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) {
major = maxVersion.major;
minor = maxVersion.minor;
} else {
major = protocolVersion.major;
minor = protocolVersion.minor;
}
try {
KeyGenerator kg = JsseJce.getKeyGenerator("SunTlsRsaPremasterSecret");
kg.init(new TlsRsaPremasterSecretParameterSpec(major, minor));
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, HandshakeInStream input,
int messageSize, PrivateKey privateKey) throws IOException {
if (privateKey.getAlgorithm().equals("RSA") == false) {
throw new SSLKeyException("Private key not of type RSA");
}
this.protocolVersion = currentVersion;
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, preMaster, null);
} catch (Exception e) {
// polish the premaster secret
preMaster = polishPreMasterSecretKey(
currentVersion, maxVersion, preMaster, 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]
*
* Note that although TLS 1.2 is not supported in this release, we still
* want to make use of the above approach to provide better protection.
*/
private SecretKey polishPreMasterSecretKey(
ProtocolVersion currentVersion, ProtocolVersion clientHelloVersion,
SecretKey secretKey, Exception failoverException) {
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 = KeyLength.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(currentVersion);
}
// 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.
*/
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(currentVersion);
} else {
if (debug != null && Debug.isOn("handshake")) {
System.out.println(
"incorrect length of premaster secret: " +
encoded.length);
}
return generateDummySecret(currentVersion);
}
}
if (debug != null && Debug.isOn("handshake") &&
failoverException != null) {
System.out.println("Error decrypting premaster secret:");
failoverException.printStackTrace(System.out);
}
return generateDummySecret(currentVersion);
}
// 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 {
KeyGenerator kg =
JsseJce.getKeyGenerator("SunTlsRsaPremasterSecret");
kg.init(new TlsRsaPremasterSecretParameterSpec
(version.major, version.minor));
return kg.generateKey();
} catch (GeneralSecurityException e) {
throw new RuntimeException("Could not generate dummy secret", e);
}
}
int messageLength() {
if (protocolVersion.v >= ProtocolVersion.TLS10.v) {
return encrypted.length + 2;
} else {
return encrypted.length;
}
}
void send(HandshakeOutStream s) throws IOException {
if (protocolVersion.v >= ProtocolVersion.TLS10.v) {
s.putBytes16(encrypted);
} else {
s.write(encrypted);
}
}
void print(PrintStream s) throws IOException {
s.println("*** ClientKeyExchange, RSA PreMasterSecret, " + protocolVersion);
}
}