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 * 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

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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;

/**

 * 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");

                }

                // We are not always able to get the encoded key of the

                // premaster secret. Pass the cheking 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) {

                    /*

                     * we never checked the client_version in server side

                     * for TLS v1.0 and SSL v3.0. For compatibility, we

                     * maintain this behavior.

                     */

                    if (currentVersion.major == encoded[0] &&

                        currentVersion.minor == encoded[1]) {

                        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]));

                }

            } else {

                if (debug != null && Debug.isOn("handshake")) {

                    System.out.println(

                        "incorrect length of premaster secret: " +

                        encoded.length);

                }

            }

        }

        if (debug != null && Debug.isOn("handshake")) {

            if (failoverException != null) {

                System.out.println("Error decrypting premaster secret:");

                failoverException.printStackTrace(System.out);

            }

            System.out.println("Generating random secret");

        }

        return generateDummySecret(clientHelloVersion);

    }

    // generate a premaster secret with the specified version number

    static SecretKey generateDummySecret(ProtocolVersion version) {

        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);

    }

}