package org.bouncycastle.crypto.paddings;import org.bouncycastle.crypto.BlockCipher;import org.bouncycastle.crypto.BufferedBlockCipher;import org.bouncycastle.crypto.CipherParameters;import org.bouncycastle.crypto.DataLengthException;import org.bouncycastle.crypto.InvalidCipherTextException;import org.bouncycastle.crypto.params.ParametersWithRandom;/** * A wrapper class that allows block ciphers to be used to process data in * a piecemeal fashion with padding. The PaddedBufferedBlockCipher * outputs a block only when the buffer is full and more data is being added, * or on a doFinal (unless the current block in the buffer is a pad block). * The default padding mechanism used is the one outlined in PKCS5/PKCS7. */public class PaddedBufferedBlockCipher    extends BufferedBlockCipher{    BlockCipherPadding  padding;    /**     * Create a buffered block cipher with the desired padding.     *     * @param cipher the underlying block cipher this buffering object wraps.     * @param padding the padding type.     */    public PaddedBufferedBlockCipher(        BlockCipher         cipher,        BlockCipherPadding  padding)    {        this.cipher = cipher;        this.padding = padding;        buf = new byte[cipher.getBlockSize()];        bufOff = 0;    }    /**     * Create a buffered block cipher PKCS7 padding     *     * @param cipher the underlying block cipher this buffering object wraps.     */    public PaddedBufferedBlockCipher(        BlockCipher     cipher)    {        this(cipher, new PKCS7Padding());    }    /**     * initialise the cipher.     *     * @param forEncryption if true the cipher is initialised for     *  encryption, if false for decryption.     * @param params the key and other data required by the cipher.     * @exception IllegalArgumentException if the params argument is     * inappropriate.     */    public void init(        boolean             forEncryption,        CipherParameters    params)        throws IllegalArgumentException    {        this.forEncryption = forEncryption;        reset();        if (params instanceof ParametersWithRandom)        {            ParametersWithRandom    p = (ParametersWithRandom)params;            padding.init(p.getRandom());            cipher.init(forEncryption, p.getParameters());        }        else        {            padding.init(null);            cipher.init(forEncryption, params);        }    }    /**     * return the minimum size of the output buffer required for an update     * plus a doFinal with an input of len bytes.     *     * @param len the length of the input.     * @return the space required to accommodate a call to update and doFinal     * with len bytes of input.     */    public int getOutputSize(        int len)    {        int total       = len + bufOff;        int leftOver    = total % buf.length;        if (leftOver == 0)        {            if (forEncryption)            {                return total + buf.length;            }            return total;        }        return total - leftOver + buf.length;    }    /**     * return the size of the output buffer required for an update      * an input of len bytes.     *     * @param len the length of the input.     * @return the space required to accommodate a call to update     * with len bytes of input.     */    public int getUpdateOutputSize(        int len)    {        int total       = len + bufOff;        int leftOver    = total % buf.length;        if (leftOver == 0)        {            return total - buf.length;        }        return total - leftOver;    }    /**     * process a single byte, producing an output block if neccessary.     *     * @param in the input byte.     * @param out the space for any output that might be produced.     * @param outOff the offset from which the output will be copied.     * @return the number of output bytes copied to out.     * @exception DataLengthException if there isn't enough space in out.     * @exception IllegalStateException if the cipher isn't initialised.     */    public int processByte(        byte        in,        byte[]      out,        int         outOff)        throws DataLengthException, IllegalStateException    {        int         resultLen = 0;        if (bufOff == buf.length)        {            resultLen = cipher.processBlock(buf, 0, out, outOff);            bufOff = 0;        }        buf[bufOff++] = in;        return resultLen;    }    /**     * process an array of bytes, producing output if necessary.     *     * @param in the input byte array.     * @param inOff the offset at which the input data starts.     * @param len the number of bytes to be copied out of the input array.     * @param out the space for any output that might be produced.     * @param outOff the offset from which the output will be copied.     * @return the number of output bytes copied to out.     * @exception DataLengthException if there isn't enough space in out.     * @exception IllegalStateException if the cipher isn't initialised.     */    public int processBytes(        byte[]      in,        int         inOff,        int         len,        byte[]      out,        int         outOff)        throws DataLengthException, IllegalStateException    {        if (len < 0)        {            throw new IllegalArgumentException("Can't have a negative input length!");        }        int blockSize   = getBlockSize();        int length      = getUpdateOutputSize(len);                if (length > 0)        {            if ((outOff + length) > out.length)            {                throw new DataLengthException("output buffer too short");            }        }        int resultLen = 0;        int gapLen = buf.length - bufOff;        if (len > gapLen)        {            System.arraycopy(in, inOff, buf, bufOff, gapLen);            resultLen += cipher.processBlock(buf, 0, out, outOff);            bufOff = 0;            len -= gapLen;            inOff += gapLen;            while (len > buf.length)            {                resultLen += cipher.processBlock(in, inOff, out, outOff + resultLen);                len -= blockSize;                inOff += blockSize;            }        }        System.arraycopy(in, inOff, buf, bufOff, len);        bufOff += len;        return resultLen;    }    /**     * Process the last block in the buffer. If the buffer is currently     * full and padding needs to be added a call to doFinal will produce     * 2 * getBlockSize() bytes.     *     * @param out the array the block currently being held is copied into.     * @param outOff the offset at which the copying starts.     * @return the number of output bytes copied to out.     * @exception DataLengthException if there is insufficient space in out for     * the output or we are decrypting and the input is not block size aligned.     * @exception IllegalStateException if the underlying cipher is not     * initialised.     * @exception InvalidCipherTextException if padding is expected and not found.     */    public int doFinal(        byte[]  out,        int     outOff)        throws DataLengthException, IllegalStateException, InvalidCipherTextException    {        int blockSize = cipher.getBlockSize();        int resultLen = 0;        if (forEncryption)        {            if (bufOff == blockSize)            {                if ((outOff + 2 * blockSize) > out.length)                {                    reset();                    throw new DataLengthException("output buffer too short");                }                resultLen = cipher.processBlock(buf, 0, out, outOff);                bufOff = 0;            }            padding.addPadding(buf, bufOff);            resultLen += cipher.processBlock(buf, 0, out, outOff + resultLen);            reset();        }        else        {            if (bufOff == blockSize)            {                resultLen = cipher.processBlock(buf, 0, buf, 0);                bufOff = 0;            }            else            {                reset();                throw new DataLengthException("last block incomplete in decryption");            }            try            {                resultLen -= padding.padCount(buf);                System.arraycopy(buf, 0, out, outOff, resultLen);            }            finally            {                reset();            }        }        return resultLen;    }}