org.gudy.bouncycastle.crypto.paddings
Class PaddedBufferedBlockCipher

java.lang.Object
  org.gudy.bouncycastle.crypto.BufferedBlockCipher
      org.gudy.bouncycastle.crypto.paddings.PaddedBufferedBlockCipher

public class PaddedBufferedBlockCipher
extends BufferedBlockCipher

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.

Field Summary

Fields inherited from class org.gudy.bouncycastle.crypto.BufferedBlockCipher

buf, bufOff, cipher, forEncryption, partialBlockOkay, pgpCFB

Constructor Summary

PaddedBufferedBlockCipher(BlockCipher cipher)
Create a buffered block cipher PKCS7 padding

PaddedBufferedBlockCipher(BlockCipher cipher, BlockCipherPadding padding)
Create a buffered block cipher with the desired padding.

Method Summary

int	doFinal(byte[] out, int outOff) Process the last block in the buffer.
int	getOutputSize(int len) return the minimum size of the output buffer required for an update plus a doFinal with an input of len bytes.
int	getUpdateOutputSize(int len) return the size of the output buffer required for an update an input of len bytes.
void	init(boolean forEncryption, CipherParameters params) initialise the cipher.
int	processByte(byte in, byte[] out, int outOff) process a single byte, producing an output block if neccessary.
int	processBytes(byte[] in, int inOff, int len, byte[] out, int outOff) process an array of bytes, producing output if necessary.

Methods inherited from class org.gudy.bouncycastle.crypto.BufferedBlockCipher

getBlockSize, getUnderlyingCipher, reset

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PaddedBufferedBlockCipher

public PaddedBufferedBlockCipher(BlockCipher cipher,
                                 BlockCipherPadding padding)

Create a buffered block cipher with the desired padding.

Parameters:

cipher - the underlying block cipher this buffering object wraps.

padding - the padding type.

PaddedBufferedBlockCipher

public PaddedBufferedBlockCipher(BlockCipher cipher)

Create a buffered block cipher PKCS7 padding

Parameters:

cipher - the underlying block cipher this buffering object wraps.

Method Detail

init

public void init(boolean forEncryption,
                 CipherParameters params)
          throws IllegalArgumentException

initialise the cipher.

Overrides:

init in class BufferedBlockCipher

Parameters:

forEncryption - if true the cipher is initialised for encryption, if false for decryption.

params - the key and other data required by the cipher.

Throws:

IllegalArgumentException - if the params argument is inappropriate.

getOutputSize

public int getOutputSize(int len)

return the minimum size of the output buffer required for an update plus a doFinal with an input of len bytes.

Overrides:

getOutputSize in class BufferedBlockCipher

Parameters:

len - the length of the input.

Returns:

the space required to accommodate a call to update and doFinal with len bytes of input.

getUpdateOutputSize

public int getUpdateOutputSize(int len)

return the size of the output buffer required for an update an input of len bytes.

Overrides:

getUpdateOutputSize in class BufferedBlockCipher

Parameters:

len - the length of the input.

Returns:

the space required to accommodate a call to update with len bytes of input.

processByte

public int processByte(byte in,
                       byte[] out,
                       int outOff)
                throws DataLengthException,
                       IllegalStateException

process a single byte, producing an output block if neccessary.

Overrides:

processByte in class BufferedBlockCipher

Parameters:

in - the input byte.

out - the space for any output that might be produced.

outOff - the offset from which the output will be copied.

Returns:

the number of output bytes copied to out.

Throws:

DataLengthException - if there isn't enough space in out.

IllegalStateException - if the cipher isn't initialised.

processBytes

public int processBytes(byte[] in,
                        int inOff,
                        int len,
                        byte[] out,
                        int outOff)
                 throws DataLengthException,
                        IllegalStateException

process an array of bytes, producing output if necessary.

Overrides:

processBytes in class BufferedBlockCipher

Parameters:

in - the input byte array.

inOff - the offset at which the input data starts.

len - the number of bytes to be copied out of the input array.

out - the space for any output that might be produced.

outOff - the offset from which the output will be copied.

Returns:

the number of output bytes copied to out.

Throws:

DataLengthException - if there isn't enough space in out.

IllegalStateException - if the cipher isn't initialised.

doFinal

public int doFinal(byte[] out,
                   int outOff)
            throws DataLengthException,
                   IllegalStateException,
                   InvalidCipherTextException

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.

Overrides:

doFinal in class BufferedBlockCipher

Parameters:

out - the array the block currently being held is copied into.

outOff - the offset at which the copying starts.

Returns:

the number of output bytes copied to out.

Throws:

DataLengthException - if there is insufficient space in out for the output or we are decrypting and the input is not block size aligned.

IllegalStateException - if the underlying cipher is not initialised.

InvalidCipherTextException - if padding is expected and not found.