| 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; |
| } |
| } |