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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * 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

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 * 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).

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 * You should have received a copy of the GNU General Public License version

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package com.sun.crypto.provider;

import java.util.Arrays;

import java.util.Locale;

import java.security.*;

import java.security.spec.*;

import javax.crypto.*;

import javax.crypto.spec.*;

import javax.crypto.BadPaddingException;

/**

 * This class represents the symmetric algorithms in its various modes

 * (<code>ECB</code>, <code>CFB</code>, <code>OFB</code>, <code>CBC</code>,

 * <code>PCBC</code>, <code>CTR</code>, and <code>CTS</code>) and

 * padding schemes (<code>PKCS5Padding</code>, <code>NoPadding</code>,

 * <code>ISO10126Padding</code>).

 *

 * @author Gigi Ankeny

 * @author Jan Luehe

 * @see ElectronicCodeBook

 * @see CipherFeedback

 * @see OutputFeedback

 * @see CipherBlockChaining

 * @see PCBC

 * @see CounterMode

 * @see CipherTextStealing

 */

final class CipherCore {

    /*

     * internal buffer

     */

    private byte[] buffer = null;

    /*

     * block size of cipher in bytes

     */

    private int blockSize = 0;

    /*

     * unit size (number of input bytes that can be processed at a time)

     */

    private int unitBytes = 0;

    /*

     * index of the content size left in the buffer

     */

    private int buffered = 0;

    /*

     * minimum number of bytes in the buffer required for

     * FeedbackCipher.encryptFinal()/decryptFinal() call.

     * update() must buffer this many bytes before starting

     * to encrypt/decrypt data.

     * currently, only the following cases have non-zero values:

     * 1) CTS mode - due to its special handling on the last two blocks

     * (the last one may be incomplete).

     * 2) GCM mode + decryption - due to its trailing tag bytes

     */

    private int minBytes = 0;

    /*

     * number of bytes needed to make the total input length a multiple

     * of the blocksize (this is used in feedback mode, when the number of

     * input bytes that are processed at a time is different from the block

     * size)

     */

    private int diffBlocksize = 0;

    /*

     * padding class

     */

    private Padding padding = null;

    /*

     * internal cipher engine

     */

    private FeedbackCipher cipher = null;

    /*

     * the cipher mode

     */

    private int cipherMode = ECB_MODE;

    /*

     * are we encrypting or decrypting?

     */

    private boolean decrypting = false;

    /*

     * Block Mode constants

     */

    private static final int ECB_MODE = 0;

    private static final int CBC_MODE = 1;

    private static final int CFB_MODE = 2;

    private static final int OFB_MODE = 3;

    private static final int PCBC_MODE = 4;

    private static final int CTR_MODE = 5;

    private static final int CTS_MODE = 6;

    private static final int GCM_MODE = 7;

    /*

     * variables used for performing the GCM (key+iv) uniqueness check.

     * To use GCM mode safely, the cipher object must be re-initialized

     * with a different combination of key + iv values for each

     * encryption operation. However, checking all past key + iv values

     * isn't feasible. Thus, we only do a per-instance check of the

     * key + iv values used in previous encryption.

     * For decryption operations, no checking is necessary.

     * NOTE: this key+iv check have to be done inside CipherCore class

     * since CipherCore class buffers potential tag bytes in GCM mode

     * and may not call GaloisCounterMode when there isn't sufficient

     * input to process.

     */

    private boolean requireReinit = false;

    private byte[] lastEncKey = null;

    private byte[] lastEncIv = null;

    /**

     * Creates an instance of CipherCore with default ECB mode and

     * PKCS5Padding.

     */

    CipherCore(SymmetricCipher impl, int blkSize) {

        blockSize = blkSize;

        unitBytes = blkSize;

        diffBlocksize = blkSize;

        /*

         * The buffer should be usable for all cipher mode and padding

         * schemes. Thus, it has to be at least (blockSize+1) for CTS.

         * In decryption mode, it also hold the possible padding block.

         */

        buffer = new byte[blockSize*2];

        // set mode and padding

        cipher = new ElectronicCodeBook(impl);

        padding = new PKCS5Padding(blockSize);

    }

    /**

     * Sets the mode of this cipher.

     *

     * @param mode the cipher mode

     *

     * @exception NoSuchAlgorithmException if the requested cipher mode does

     * not exist for this cipher

     */

    void setMode(String mode) throws NoSuchAlgorithmException {

        if (mode == null)

            throw new NoSuchAlgorithmException("null mode");

        String modeUpperCase = mode.toUpperCase(Locale.ENGLISH);

        if (modeUpperCase.equals("ECB")) {

            return;

        }

        SymmetricCipher rawImpl = cipher.getEmbeddedCipher();

        if (modeUpperCase.equals("CBC")) {

            cipherMode = CBC_MODE;

            cipher = new CipherBlockChaining(rawImpl);

        } else if (modeUpperCase.equals("CTS")) {

            cipherMode = CTS_MODE;

            cipher = new CipherTextStealing(rawImpl);

            minBytes = blockSize+1;

            padding = null;

        } else if (modeUpperCase.equals("CTR")) {

            cipherMode = CTR_MODE;

            cipher = new CounterMode(rawImpl);

            unitBytes = 1;

            padding = null;

        }  else if (modeUpperCase.startsWith("GCM")) {

            // can only be used for block ciphers w/ 128-bit block size

            if (blockSize != 16) {

                throw new NoSuchAlgorithmException

                    ("GCM mode can only be used for AES cipher");

            }

            cipherMode = GCM_MODE;

            cipher = new GaloisCounterMode(rawImpl);

            padding = null;

        } else if (modeUpperCase.startsWith("CFB")) {

            cipherMode = CFB_MODE;

            unitBytes = getNumOfUnit(mode, "CFB".length(), blockSize);

            cipher = new CipherFeedback(rawImpl, unitBytes);

        } else if (modeUpperCase.startsWith("OFB")) {

            cipherMode = OFB_MODE;

            unitBytes = getNumOfUnit(mode, "OFB".length(), blockSize);

            cipher = new OutputFeedback(rawImpl, unitBytes);

        } else if (modeUpperCase.equals("PCBC")) {

            cipherMode = PCBC_MODE;

            cipher = new PCBC(rawImpl);

        }

        else {

            throw new NoSuchAlgorithmException("Cipher mode: " + mode

                                               + " not found");

        }

    }

    private static int getNumOfUnit(String mode, int offset, int blockSize)

        throws NoSuchAlgorithmException {

        int result = blockSize; // use blockSize as default value

        if (mode.length() > offset) {

            int numInt;

            try {

                Integer num = Integer.valueOf(mode.substring(offset));

                numInt = num.intValue();

                result = numInt >> 3;

            } catch (NumberFormatException e) {

                throw new NoSuchAlgorithmException

                    ("Algorithm mode: " + mode + " not implemented");

            }

            if ((numInt % 8 != 0) || (result > blockSize)) {

                throw new NoSuchAlgorithmException

                    ("Invalid algorithm mode: " + mode);

            }

        }

        return result;

    }

    /**

     * Sets the padding mechanism of this cipher.

     *

     * @param padding the padding mechanism

     *

     * @exception NoSuchPaddingException if the requested padding mechanism

     * does not exist

     */

    void setPadding(String paddingScheme)

        throws NoSuchPaddingException

    {

        if (paddingScheme == null) {

            throw new NoSuchPaddingException("null padding");

        }

        if (paddingScheme.equalsIgnoreCase("NoPadding")) {

            padding = null;

        } else if (paddingScheme.equalsIgnoreCase("ISO10126Padding")) {

            padding = new ISO10126Padding(blockSize);

        } else if (!paddingScheme.equalsIgnoreCase("PKCS5Padding")) {

            throw new NoSuchPaddingException("Padding: " + paddingScheme

                                             + " not implemented");

        }

        if ((padding != null) &&

            ((cipherMode == CTR_MODE) || (cipherMode == CTS_MODE)

             || (cipherMode == GCM_MODE))) {

            padding = null;

            String modeStr = null;

            switch (cipherMode) {

            case CTR_MODE:

                modeStr = "CTR";

                break;

            case GCM_MODE:

                modeStr = "GCM";

                break;

            case CTS_MODE:

                modeStr = "CTS";

                break;

            default:

                // should never happen

            }

            if (modeStr != null) {

                throw new NoSuchPaddingException

                    (modeStr + " mode must be used with NoPadding");

            }

        }

    }

    /**

     * Returns the length in bytes that an output buffer would need to be in

     * order to hold the result of the next <code>update</code> or

     * <code>doFinal</code> operation, given the input length

     * <code>inputLen</code> (in bytes).

     *

     * <p>This call takes into account any unprocessed (buffered) data from a

     * previous <code>update</code> call, padding, and AEAD tagging.

     *

     * <p>The actual output length of the next <code>update</code> or

     * <code>doFinal</code> call may be smaller than the length returned by

     * this method.

     *

     * @param inputLen the input length (in bytes)

     *

     * @return the required output buffer size (in bytes)

     */

    int getOutputSize(int inputLen) {

        int totalLen = buffered + inputLen;

        // GCM: this call may be for either update() or doFinal(), so have to

        // return the larger value of both

        // Encryption: based on doFinal value: inputLen + tag

        // Decryption: based on update value: inputLen

        if (!decrypting && (cipherMode == GCM_MODE)) {

            return (totalLen + ((GaloisCounterMode) cipher).getTagLen());

        }

        if (padding == null) {

            return totalLen;

        }

        if (decrypting) {

            return totalLen;

        }

        if (unitBytes != blockSize) {

            if (totalLen < diffBlocksize) {

                return diffBlocksize;

            } else {

                return (totalLen + blockSize -

                        ((totalLen - diffBlocksize) % blockSize));

            }

        } else {

            return totalLen + padding.padLength(totalLen);

        }

    }

    private int getOutputSizeByOperation(int inputLen, boolean isDoFinal) {

        int totalLen = 0;

        switch (cipherMode) {

        case GCM_MODE:

            totalLen = buffered + inputLen;

            if (isDoFinal) {

                int tagLen = ((GaloisCounterMode) cipher).getTagLen();

                if (decrypting) {

                    // need to get the actual value from cipher??

                    // deduct tagLen

                    totalLen -= tagLen;

                } else {

                    totalLen += tagLen;

                }

            }

            if (totalLen < 0) {

                totalLen = 0;

            }

            break;

        default:

             totalLen  = getOutputSize(inputLen);

             break;

        }

        return totalLen;

    }

    /**

     * Returns the initialization vector (IV) in a new buffer.

     *

     * <p>This is useful in the case where a random IV has been created

     * (see <a href = "#init">init</a>),

     * or in the context of password-based encryption or

     * decryption, where the IV is derived from a user-provided password.

     *

     * @return the initialization vector in a new buffer, or null if the

     * underlying algorithm does not use an IV, or if the IV has not yet

     * been set.

     */

    byte[] getIV() {

        byte[] iv = cipher.getIV();

        return (iv == null) ? null : iv.clone();

    }

    /**

     * Returns the parameters used with this cipher.

     *

     * <p>The returned parameters may be the same that were used to initialize

     * this cipher, or may contain the default set of parameters or a set of

     * randomly generated parameters used by the underlying cipher

     * implementation (provided that the underlying cipher implementation

     * uses a default set of parameters or creates new parameters if it needs

     * parameters but was not initialized with any).

     *

     * @return the parameters used with this cipher, or null if this cipher

     * does not use any parameters.

     */

    AlgorithmParameters getParameters(String algName) {

        if (cipherMode == ECB_MODE) {

            return null;

        }

        AlgorithmParameters params = null;

        AlgorithmParameterSpec spec;

        byte[] iv = getIV();

        if (iv == null) {

            // generate spec using default value

            if (cipherMode == GCM_MODE) {

                iv = new byte[GaloisCounterMode.DEFAULT_IV_LEN];

            } else {

                iv = new byte[blockSize];

            }

            SunJCE.getRandom().nextBytes(iv);

        }

        if (cipherMode == GCM_MODE) {

            algName = "GCM";

            spec = new GCMParameterSpec

                (((GaloisCounterMode) cipher).getTagLen()*8, iv);

        } else {

           if (algName.equals("RC2")) {

               RC2Crypt rawImpl = (RC2Crypt) cipher.getEmbeddedCipher();

               spec = new RC2ParameterSpec

                   (rawImpl.getEffectiveKeyBits(), iv);

           } else {

               spec = new IvParameterSpec(iv);

           }

        }

        try {

        } catch (NoSuchAlgorithmException nsae) {

            // should never happen

            throw new RuntimeException("Cannot find " + algName +

                " AlgorithmParameters implementation in SunJCE provider");

        } catch (InvalidParameterSpecException ipse) {

            // should never happen

            throw new RuntimeException(spec.getClass() + " not supported");

        }

        return params;

    }

    /**

     * Initializes this cipher with a key and a source of randomness.

     *

     * <p>The cipher is initialized for one of the following four operations:

     * encryption, decryption, key wrapping or key unwrapping, depending on

     * the value of <code>opmode</code>.

     *

     * <p>If this cipher requires an initialization vector (IV), it will get

     * it from <code>random</code>.

     * This behaviour should only be used in encryption or key wrapping

     * mode, however.

     * When initializing a cipher that requires an IV for decryption or

     * key unwrapping, the IV

     * (same IV that was used for encryption or key wrapping) must be provided

     * explicitly as a

     * parameter, in order to get the correct result.

     *

     * <p>This method also cleans existing buffer and other related state

     * information.

     *

     * @param opmode the operation mode of this cipher (this is one of

     * the following:

     * <code>ENCRYPT_MODE</code>, <code>DECRYPT_MODE</code>,

     * <code>WRAP_MODE</code> or <code>UNWRAP_MODE</code>)

     * @param key the secret key

     * @param random the source of randomness

     *

     * @exception InvalidKeyException if the given key is inappropriate for

     * initializing this cipher

     */

    void init(int opmode, Key key, SecureRandom random)

            throws InvalidKeyException {

        try {

            init(opmode, key, (AlgorithmParameterSpec)null, random);

        } catch (InvalidAlgorithmParameterException e) {

            throw new InvalidKeyException(e.getMessage());

        }

    }

    /**

     * Initializes this cipher with a key, a set of

     * algorithm parameters, and a source of randomness.

     *

     * <p>The cipher is initialized for one of the following four operations:

     * encryption, decryption, key wrapping or key unwrapping, depending on

     * the value of <code>opmode</code>.

     *

     * <p>If this cipher (including its underlying feedback or padding scheme)

     * requires any random bytes, it will get them from <code>random</code>.

     *

     * @param opmode the operation mode of this cipher (this is one of

     * the following:

     * <code>ENCRYPT_MODE</code>, <code>DECRYPT_MODE</code>,

     * <code>WRAP_MODE</code> or <code>UNWRAP_MODE</code>)

     * @param key the encryption key

     * @param params the algorithm parameters

     * @param random the source of randomness

     *

     * @exception InvalidKeyException if the given key is inappropriate for

     * initializing this cipher

     * @exception InvalidAlgorithmParameterException if the given algorithm

     * parameters are inappropriate for this cipher

     */

    void init(int opmode, Key key, AlgorithmParameterSpec params,

            SecureRandom random)

            throws InvalidKeyException, InvalidAlgorithmParameterException {

        decrypting = (opmode == Cipher.DECRYPT_MODE)

                  || (opmode == Cipher.UNWRAP_MODE);

        byte[] keyBytes = getKeyBytes(key);

        int tagLen = -1;

        byte[] ivBytes = null;