/*

 * Copyright (c) 1996, 2010, 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.ByteArrayInputStream;

import java.io.IOException;

import java.util.Hashtable;

import java.security.*;

import javax.crypto.*;

import javax.crypto.spec.SecretKeySpec;

import javax.crypto.spec.IvParameterSpec;

import java.nio.*;

import sun.security.ssl.CipherSuite.*;

import static sun.security.ssl.CipherSuite.*;

import sun.misc.HexDumpEncoder;

/**

 * This class handles bulk data enciphering/deciphering for each SSLv3

 * message.  This provides data confidentiality.  Stream ciphers (such

 * as RC4) don't need to do padding; block ciphers (e.g. DES) need it.

 *

 * Individual instances are obtained by calling the static method

 * newCipherBox(), which should only be invoked by BulkCipher.newCipher().

 *

 * In RFC 2246, with bock ciphers in CBC mode, the Initialization

 * Vector (IV) for the first record is generated with the other keys

 * and secrets when the security parameters are set.  The IV for

 * subsequent records is the last ciphertext block from the previous

 * record.

 *

 * In RFC 4346, the implicit Initialization Vector (IV) is replaced

 * with an explicit IV to protect against CBC attacks.  RFC 4346

 * recommends two algorithms used to generated the per-record IV.

 * The implementation uses the algorithm (2)(b), as described at

 * section 6.2.3.2 of RFC 4346.

 *

 * The usage of IV in CBC block cipher can be illustrated in

 * the following diagrams.

 *

 *   (random)

 *        R         P1                    IV        C1

 *        |          |                     |         |

 *  SIV---+    |-----+    |-...            |-----    |------

 *        |    |     |    |                |    |    |     |

 *     +----+  |  +----+  |             +----+  |  +----+  |

 *     | Ek |  |  + Ek +  |             | Dk |  |  | Dk |  |

 *     +----+  |  +----+  |             +----+  |  +----+  |

 *        |    |     |    |                |    |    |     |

 *        |----|     |----|           SIV--+    |----|     |-...

 *        |          |                     |       |

 *       IV         C1                     R      P1

 *                                     (discard)

 *

 *       CBC Encryption                    CBC Decryption

 *

 * NOTE that any ciphering involved in key exchange (e.g. with RSA) is

 * handled separately.

 *

 * @author David Brownell

 * @author Andreas Sterbenz

 */

final class CipherBox {

    // A CipherBox that implements the identity operation

    final static CipherBox NULL = new CipherBox();

    /* Class and subclass dynamic debugging support */

    private static final Debug debug = Debug.getInstance("ssl");

    // the protocol version this cipher conforms to

    private final ProtocolVersion protocolVersion;

    // cipher object

    private final Cipher cipher;

    /**

     * Cipher blocksize, 0 for stream ciphers

     */

    private int blockSize;

    /**

     * secure random

     */

    private SecureRandom random;

    /**

     * Fixed masks of various block size, as the initial decryption IVs

     * for TLS 1.1 or later.

     *

     * For performance, we do not use random IVs. As the initial decryption

     * IVs will be discarded by TLS decryption processes, so the fixed masks

     * do not hurt cryptographic strength.

     */

    private static Hashtable<Integer, IvParameterSpec> masks;

    /**

     * NULL cipherbox. Identity operation, no encryption.

     */

    private CipherBox() {

        this.protocolVersion = ProtocolVersion.DEFAULT;

        this.cipher = null;

    }

    /**

     * Construct a new CipherBox using the cipher transformation.

     *

     * @exception NoSuchAlgorithmException if no appropriate JCE Cipher

     * implementation could be found.

     */

    private CipherBox(ProtocolVersion protocolVersion, BulkCipher bulkCipher,

            SecretKey key, IvParameterSpec iv, SecureRandom random,

            boolean encrypt) throws NoSuchAlgorithmException {

        try {

            this.protocolVersion = protocolVersion;

            this.cipher = JsseJce.getCipher(bulkCipher.transformation);

            int mode = encrypt ? Cipher.ENCRYPT_MODE : Cipher.DECRYPT_MODE;

            if (random == null) {

                random = JsseJce.getSecureRandom();

            }

            this.random = random;

            /*

             * RFC 4346 recommends two algorithms used to generated the

             * per-record IV. The implementation uses the algorithm (2)(b),

             * as described at section 6.2.3.2 of RFC 4346.

             *

             * As we don't care about the initial IV value for TLS 1.1 or

             * later, so if the "iv" parameter is null, we use the default

             * value generated by Cipher.init() for encryption, and a fixed

             * mask for decryption.

             */

            if (iv == null && bulkCipher.ivSize != 0 &&

                    mode == Cipher.DECRYPT_MODE &&

                    protocolVersion.v >= ProtocolVersion.TLS11.v) {

                iv = getFixedMask(bulkCipher.ivSize);

            }

            cipher.init(mode, key, iv, random);

            // Do not call getBlockSize until after init()

            // otherwise we would disrupt JCE delayed provider selection

            blockSize = cipher.getBlockSize();

            // some providers implement getBlockSize() incorrectly

            if (blockSize == 1) {

                blockSize = 0;

            }

        } catch (NoSuchAlgorithmException e) {

            throw e;

        } catch (Exception e) {

            throw new NoSuchAlgorithmException

                    ("Could not create cipher " + bulkCipher, e);

        } catch (ExceptionInInitializerError e) {

            throw new NoSuchAlgorithmException

                    ("Could not create cipher " + bulkCipher, e);

        }

    }

    /*

     * Factory method to obtain a new CipherBox object.

     */

    static CipherBox newCipherBox(ProtocolVersion version, BulkCipher cipher,

            SecretKey key, IvParameterSpec iv, SecureRandom random,

            boolean encrypt) throws NoSuchAlgorithmException {

        if (cipher.allowed == false) {

            throw new NoSuchAlgorithmException("Unsupported cipher " + cipher);

        }

        if (cipher == B_NULL) {

            return NULL;

        } else {

            return new CipherBox(version, cipher, key, iv, random, encrypt);

        }

    }

    /*

     * Get a fixed mask, as the initial decryption IVs for TLS 1.1 or later.

     */

    private static IvParameterSpec getFixedMask(int ivSize) {

        if (masks == null) {

            masks = new Hashtable<Integer, IvParameterSpec>(5);

        }

        IvParameterSpec iv = masks.get(ivSize);

        if (iv == null) {

            iv = new IvParameterSpec(new byte[ivSize]);

            masks.put(ivSize, iv);

        }

        return iv;

    }

    /*

     * Encrypts a block of data, returning the size of the

     * resulting block.

     */

    int encrypt(byte[] buf, int offset, int len) {

        if (cipher == null) {

            return len;

        }

        try {

            if (blockSize != 0) {

                // TLSv1.1 needs a IV block

                if (protocolVersion.v >= ProtocolVersion.TLS11.v) {

                    // generate a random number

                    byte[] prefix = new byte[blockSize];

                    random.nextBytes(prefix);

                    // move forward the plaintext

                    System.arraycopy(buf, offset,

                                     buf, offset + prefix.length, len);

                    // prefix the plaintext

                    System.arraycopy(prefix, 0,

                                     buf, offset, prefix.length);

                    len += prefix.length;

                }

                len = addPadding(buf, offset, len, blockSize);

            }

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

                try {

                    HexDumpEncoder hd = new HexDumpEncoder();

                    System.out.println(

                        "Padded plaintext before ENCRYPTION:  len = "

                        + len);

                    hd.encodeBuffer(

                        new ByteArrayInputStream(buf, offset, len),

                        System.out);

                } catch (IOException e) { }

            }

            int newLen = cipher.update(buf, offset, len, buf, offset);

            if (newLen != len) {

                // catch BouncyCastle buffering error

                throw new RuntimeException("Cipher buffering error " +

                    "in JCE provider " + cipher.getProvider().getName());

            }

            return newLen;

        } catch (ShortBufferException e) {

            throw new ArrayIndexOutOfBoundsException(e.toString());

        }

    }

    /*

     * Encrypts a ByteBuffer block of data, returning the size of the

     * resulting block.

     *

     * The byte buffers position and limit initially define the amount

     * to encrypt.  On return, the position and limit are

     * set to last position padded/encrypted.  The limit may have changed

     * because of the added padding bytes.

     */

    int encrypt(ByteBuffer bb) {

        int len = bb.remaining();

        if (cipher == null) {

            bb.position(bb.limit());

            return len;

        }

        try {

            int pos = bb.position();

            if (blockSize != 0) {

                // TLSv1.1 needs a IV block

                if (protocolVersion.v >= ProtocolVersion.TLS11.v) {

                    // generate a random number

                    byte[] prefix = new byte[blockSize];

                    random.nextBytes(prefix);

                    // move forward the plaintext

                    byte[] buf = null;

                    int limit = bb.limit();

                    if (bb.hasArray()) {

                        buf = bb.array();

                        System.arraycopy(buf, pos,

                                buf, pos + prefix.length, limit - pos);

                        bb.limit(limit + prefix.length);

                    } else {

                        buf = new byte[limit - pos];

                        bb.get(buf, 0, limit - pos);

                        bb.position(pos + prefix.length);

                        bb.limit(limit + prefix.length);

                        bb.put(buf);

                    }

                    bb.position(pos);

                    // prefix the plaintext

                    bb.put(prefix);

                    bb.position(pos);

                }

                // addPadding adjusts pos/limit

                len = addPadding(bb, blockSize);

                bb.position(pos);

            }

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

                try {

                    HexDumpEncoder hd = new HexDumpEncoder();

                    System.out.println(

                        "Padded plaintext before ENCRYPTION:  len = "

                        + len);

                    hd.encodeBuffer(bb, System.out);

                } catch (IOException e) { }

                /*

                 * reset back to beginning

                 */

                bb.position(pos);

            }

            /*

             * Encrypt "in-place".  This does not add its own padding.

             */

            ByteBuffer dup = bb.duplicate();

            int newLen = cipher.update(dup, bb);

            if (bb.position() != dup.position()) {

                throw new RuntimeException("bytebuffer padding error");

            }

            if (newLen != len) {

                // catch BouncyCastle buffering error

                throw new RuntimeException("Cipher buffering error " +

                    "in JCE provider " + cipher.getProvider().getName());

            }

            return newLen;

        } catch (ShortBufferException e) {

            RuntimeException exc = new RuntimeException(e.toString());

            exc.initCause(e);

            throw exc;

        }

    }

    /*

     * Decrypts a block of data, returning the size of the

     * resulting block if padding was required.

     *

     * For SSLv3 and TLSv1.0, with block ciphers in CBC mode the

     * Initialization Vector (IV) for the first record is generated by

     * the handshake protocol, the IV for subsequent records is the

     * last ciphertext block from the previous record.

     *

     * From TLSv1.1, the implicit IV is replaced with an explicit IV to

     * protect against CBC attacks.

     *

     * Differentiating between bad_record_mac and decryption_failed alerts

     * may permit certain attacks against CBC mode. It is preferable to

     * uniformly use the bad_record_mac alert to hide the specific type of

     * the error.

     */

    int decrypt(byte[] buf, int offset, int len) throws BadPaddingException {

        if (cipher == null) {

            return len;

        }

        try {

            int newLen = cipher.update(buf, offset, len, buf, offset);

            if (newLen != len) {

                // catch BouncyCastle buffering error

                throw new RuntimeException("Cipher buffering error " +

                    "in JCE provider " + cipher.getProvider().getName());

            }

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

                try {

                    HexDumpEncoder hd = new HexDumpEncoder();

                    System.out.println(

                        "Padded plaintext after DECRYPTION:  len = "

                        + newLen);

                    hd.encodeBuffer(

                        new ByteArrayInputStream(buf, offset, newLen),

                        System.out);

                } catch (IOException e) { }

            }

            if (blockSize != 0) {

                newLen = removePadding(buf, offset, newLen,

                             blockSize, protocolVersion);

                if (protocolVersion.v >= ProtocolVersion.TLS11.v) {

                    if (newLen < blockSize) {

                        throw new BadPaddingException("invalid explicit IV");

                    }

                    // discards the first cipher block, the IV component.

                    System.arraycopy(buf, offset + blockSize,

                                     buf, offset, newLen - blockSize);

                    newLen -= blockSize;

                }

            }

            return newLen;

        } catch (ShortBufferException e) {

            throw new ArrayIndexOutOfBoundsException(e.toString());

        }

    }

    /*

     * Decrypts a block of data, returning the size of the

     * resulting block if padding was required.  position and limit

     * point to the end of the decrypted/depadded data.  The initial

     * limit and new limit may be different, given we may

     * have stripped off some padding bytes.

     *

     *  @see decrypt(byte[], int, int)

     */

    int decrypt(ByteBuffer bb) throws BadPaddingException {

        int len = bb.remaining();

        if (cipher == null) {

            bb.position(bb.limit());

            return len;

        }

        try {

            /*

             * Decrypt "in-place".

             */

            int pos = bb.position();

            ByteBuffer dup = bb.duplicate();

            int newLen = cipher.update(dup, bb);

            if (newLen != len) {

                // catch BouncyCastle buffering error

                throw new RuntimeException("Cipher buffering error " +

                    "in JCE provider " + cipher.getProvider().getName());

            }

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

                bb.position(pos);

                try {

                    HexDumpEncoder hd = new HexDumpEncoder();

                    System.out.println(

                        "Padded plaintext after DECRYPTION:  len = "

                        + newLen);

                    hd.encodeBuffer(bb, System.out);

                } catch (IOException e) { }

            }

            /*

             * Remove the block padding.

             */

            if (blockSize != 0) {

                bb.position(pos);

                newLen = removePadding(bb, blockSize, protocolVersion);

                if (protocolVersion.v >= ProtocolVersion.TLS11.v) {

                    if (newLen < blockSize) {

                        throw new BadPaddingException("invalid explicit IV");

                    }

                    // discards the first cipher block, the IV component.

                    byte[] buf = null;

                    int limit = bb.limit();

                    if (bb.hasArray()) {

                        buf = bb.array();

                        System.arraycopy(buf, pos + blockSize,

                                         buf, pos, limit - pos - blockSize);

                        bb.limit(limit - blockSize);

                    } else {

                        buf = new byte[limit - pos - blockSize];

                        bb.position(pos + blockSize);

                        bb.get(buf);

                        bb.position(pos);

                        bb.put(buf);

                        bb.limit(limit - blockSize);

                    }

                    // reset the position to the end of the decrypted data

                    limit = bb.limit();

                    bb.position(limit);

                }

            }

            return newLen;