org.bouncycastle.crypto

Class BufferedBlockCipher

java.lang.Object

org.bouncycastle.crypto.BufferedBlockCipher

Direct Known Subclasses:

CTSBlockCipher, PaddedBufferedBlockCipher

public class BufferedBlockCipher
extends Object

A wrapper class that allows block ciphers to be used to process data in a piecemeal fashion. The BufferedBlockCipher outputs a block only when the buffer is full and more data is being added, or on a doFinal.

Note: in the case where the underlying cipher is either a CFB cipher or an OFB one the last block may not be a multiple of the block size.

Field Summary

Fields

Modifier and Type	Field and Description
protected byte[]	buf
protected int	bufOff
protected BlockCipher	cipher
protected boolean	forEncryption
protected boolean	partialBlockOkay
protected boolean	pgpCFB

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	BufferedBlockCipher() constructor for subclasses
	BufferedBlockCipher(BlockCipher cipher) Create a buffered block cipher without padding.

Method Summary

Modifier and Type	Method and Description
int	doFinal(byte[] out, int outOff) Process the last block in the buffer.
int	getBlockSize() return the blocksize for the underlying cipher.
int	getOutputSize(int length) return the size of the output buffer required for an update plus a doFinal with an input of 'length' bytes.
BlockCipher	getUnderlyingCipher() return the cipher this object wraps.
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 necessary.
int	processBytes(byte[] in, int inOff, int len, byte[] out, int outOff) process an array of bytes, producing output if necessary.
void	reset() Reset the buffer and cipher.

Methods inherited from class java.lang.Object

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

Field Detail

buf

protected byte[] buf

bufOff

protected int bufOff

forEncryption

protected boolean forEncryption

cipher

protected BlockCipher cipher

partialBlockOkay

protected boolean partialBlockOkay

pgpCFB

protected boolean pgpCFB

Constructor Detail

BufferedBlockCipher

protected BufferedBlockCipher()

constructor for subclasses

BufferedBlockCipher

public BufferedBlockCipher(BlockCipher cipher)

Create a buffered block cipher without padding.

Parameters:

cipher - the underlying block cipher this buffering object wraps.

Method Detail

getUnderlyingCipher

public BlockCipher getUnderlyingCipher()

return the cipher this object wraps.

Returns:

the cipher this object wraps.

init

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

initialise the cipher.

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.

getBlockSize

public int getBlockSize()

return the blocksize for the underlying cipher.

Returns:

the blocksize for the underlying cipher.

getUpdateOutputSize

public int getUpdateOutputSize(int len)

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

Parameters:

len - the length of the input.

Returns:

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

getOutputSize

public int getOutputSize(int length)

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

Parameters:

length - the length of the input.

Returns:

the space required to accommodate a call to update and doFinal with 'length' 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 necessary.

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.

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.

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 the input is not block size aligned and should be.

IllegalStateException - if the underlying cipher is not initialised.

InvalidCipherTextException - if padding is expected and not found.

DataLengthException - if the input is not block size aligned.

reset

public void reset()

Reset the buffer and cipher. After resetting the object is in the same state as it was after the last init (if there was one).