/*
 * Copyright (c) 1996, 2016, 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 javax.crypto.*;

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.
/**
 * 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 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.
     */
    @SuppressWarnings("deprecation")
    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: " +
                publicKey.getAlgorithm());
        }
        this.protocolVersion = protocolVersion;

        try {
            String s = protocolVersion.useTLS12PlusSpec() ?
                "SunTls12RsaPremasterSecret" : "SunTlsRsaPremasterSecret";
            KeyGenerator kg = JsseJce.getKeyGenerator(s);
            kg.init(new TlsRsaPremasterSecretParameterSpec(
                    maxVersion.v, protocolVersion.v), 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);
        }
    }

    /*
     * Retrieving the cipher's provider name for the debug purposes
     * can throw an exception by itself.
     */
    private static String safeProviderName(Cipher cipher) {
        try {
            return cipher.getProvider().toString();
        } catch (Exception e) {
            if (debug != null && Debug.isOn("handshake")) {
                System.out.println("Retrieving The Cipher provider name" +
                        " caused exception " + e.getMessage());
            }
        }
        try {
            return cipher.toString() + " (provider name not available)";
        } catch (Exception e) {
            if (debug != null && Debug.isOn("handshake")) {
                System.out.println("Retrieving The Cipher name" +
                        " caused exception " + e.getMessage());
            }
        }
        return "(cipher/provider names not available)";
    }

    /*
     * Server gets the PKCS #1 (block format 02) data, decrypts
     * it with its private key.
     */
    @SuppressWarnings("deprecation")
    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: " +
                 privateKey.getAlgorithm());
        }

        if (currentVersion.useTLS10PlusSpec()) {
            encrypted = input.getBytes16();
        } else {
            encrypted = new byte [messageSize];
            if (input.read(encrypted) != messageSize) {
                throw new SSLProtocolException(
                        "SSL: read PreMasterSecret: short read");
            }
        }

        byte[] encoded = null;
        try {
            boolean needFailover = false;
            Cipher cipher = JsseJce.getCipher(JsseJce.CIPHER_RSA_PKCS1);
            try {
                // Try UNWRAP_MODE mode firstly.
                cipher.init(Cipher.UNWRAP_MODE, privateKey,
                        new TlsRsaPremasterSecretParameterSpec(
                                maxVersion.v, currentVersion.v),
                        generator);

                // The provider selection can be delayed, please don't call
                // any Cipher method before the call to Cipher.init().
                needFailover = !KeyUtil.isOracleJCEProvider(
                        cipher.getProvider().getName());
            } catch (InvalidKeyException | UnsupportedOperationException iue) {
                if (debug != null && Debug.isOn("handshake")) {
                    System.out.println("The Cipher provider "
                            + safeProviderName(cipher)
                            + " caused exception: " + iue.getMessage());
                }

                needFailover = true;
            }

            if (needFailover) {
                // The cipher might be spoiled by unsuccessful call to init(),
                // so request a fresh instance
                cipher = JsseJce.getCipher(JsseJce.CIPHER_RSA_PKCS1);

                // Use DECRYPT_MODE and dispose the previous initialization.
                cipher.init(Cipher.DECRYPT_MODE, privateKey);
                boolean failed = false;
                try {
                    encoded = cipher.doFinal(encrypted);
                } catch (BadPaddingException bpe) {
                    // Note: encoded == null
                    failed = true;
                }
                encoded = KeyUtil.checkTlsPreMasterSecretKey(
                                maxVersion.v, currentVersion.v,
                                generator, encoded, failed);
                preMaster = generatePreMasterSecret(
                                maxVersion.v, currentVersion.v,
                                encoded, generator);
            } else {
                // the cipher should have been initialized
                preMaster = (SecretKey)cipher.unwrap(encrypted,
                        "TlsRsaPremasterSecret", Cipher.SECRET_KEY);
            }
        } catch (InvalidKeyException ibk) {
            // the message is too big to process with RSA
            throw new SSLException(
                "Unable to process PreMasterSecret", ibk);
        } catch (Exception e) {
            // unlikely to happen, otherwise, must be a provider exception
            if (debug != null && Debug.isOn("handshake")) {
                System.out.println("RSA premaster secret decryption error:");
                e.printStackTrace(System.out);
            }
            throw new RuntimeException("Could not generate dummy secret", e);
        }
    }

    // generate a premaster secret with the specified version number
    @SuppressWarnings("deprecation")
    private static SecretKey generatePreMasterSecret(
            int clientVersion, int serverVersion,
            byte[] encodedSecret, SecureRandom generator) {

        if (debug != null && Debug.isOn("handshake")) {
            System.out.println("Generating a premaster secret");
        }

        try {
            String s = ((clientVersion >= ProtocolVersion.TLS12.v) ?
                "SunTls12RsaPremasterSecret" : "SunTlsRsaPremasterSecret");
            KeyGenerator kg = JsseJce.getKeyGenerator(s);
            kg.init(new TlsRsaPremasterSecretParameterSpec(
                    clientVersion, serverVersion, encodedSecret),
                    generator);
            return kg.generateKey();
        } catch (InvalidAlgorithmParameterException |
                NoSuchAlgorithmException iae) {
            // unlikely to happen, otherwise, must be a provider exception
            if (debug != null && Debug.isOn("handshake")) {
                System.out.println("RSA premaster secret generation error:");
                iae.printStackTrace(System.out);
            }
            throw new RuntimeException("Could not generate premaster secret", iae);
        }
    }

    @Override
    int messageType() {
        return ht_client_key_exchange;
    }

    @Override
    int messageLength() {
        if (protocolVersion.useTLS10PlusSpec()) {
            return encrypted.length + 2;
        } else {
            return encrypted.length;
        }
    }

    @Override
    void send(HandshakeOutStream s) throws IOException {
        if (protocolVersion.useTLS10PlusSpec()) {
            s.putBytes16(encrypted);
        } else {
            s.write(encrypted);
        }
    }

    @Override
    void print(PrintStream s) throws IOException {
        String version = "version not available/extractable";

        byte[] ba = preMaster.getEncoded();
        if (ba != null && ba.length >= 2) {
            version = ProtocolVersion.valueOf(ba[0], ba[1]).name;
        }

        s.println("*** ClientKeyExchange, RSA PreMasterSecret, " + version);
    }
}