org.bouncycastle.crypto.modes

Class PaddedBlockCipher


public class PaddedBlockCipher
extends BufferedBlockCipher

A wrapper class that allows block ciphers to be used to process data in a piecemeal fashion with PKCS5/PKCS7 padding. The PaddedBlockCipher 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 padding mechanism used is the one outlined in PKCS5/PKCS7.

Field Summary

Fields inherited from class org.bouncycastle.crypto.BufferedBlockCipher

buf, bufOff, cipher, forEncryption, partialBlockOkay, pgpCFB

Constructor Summary

PaddedBlockCipher(BlockCipher cipher)
Create a buffered block cipher with, or without, padding.

Method Summary

int
doFinal(byte[] out, int outOff)
Process the last block in the buffer.
int
getOutputSize(int len)
return the 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.
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.bouncycastle.crypto.BufferedBlockCipher

doFinal, getBlockSize, getOutputSize, getUnderlyingCipher, getUpdateOutputSize, init, processByte, processBytes, reset

Constructor Details

PaddedBlockCipher

public PaddedBlockCipher(BlockCipher cipher)
Create a buffered block cipher with, or without, padding.

Parameters:
cipher - the underlying block cipher this buffering object wraps.

Method Details

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 interface BufferedBlockCipher

Parameters:
out - the array the block currently being held is copied into.
outOff - the offset at which the copying starts.

Throws:
InvalidCipherTextException - if padding is expected and not found.


getOutputSize

public int getOutputSize(int len)
return the size of the output buffer required for an update plus a doFinal with an input of len bytes.
Overrides:
getOutputSize in interface 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 interface 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 interface 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.

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


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 interface 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.

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