org.bouncycastle.crypto

Class BufferedBlockCipher

Known Direct Subclasses:
CTSBlockCipher, PaddedBlockCipher, PaddedBufferedBlockCipher

public class BufferedBlockCipher
extends java.lang.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

protected byte[]
buf
protected int
bufOff
protected BlockCipher
cipher
protected boolean
forEncryption
protected boolean
partialBlockOkay
protected boolean
pgpCFB

Constructor Summary

BufferedBlockCipher()
constructor for subclasses
BufferedBlockCipher(BlockCipher cipher)
Create a buffered block cipher without padding.

Method Summary

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

Field Details

buf

protected byte[] buf

bufOff

protected int bufOff

cipher

protected BlockCipher cipher

forEncryption

protected boolean forEncryption

partialBlockOkay

protected boolean partialBlockOkay

pgpCFB

protected boolean pgpCFB

Constructor Details

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 Details

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:
InvalidCipherTextException - if padding is expected and not found.

getBlockSize

public int getBlockSize()
return the blocksize for the underlying cipher.
Returns:
the blocksize for the underlying cipher.

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.
Parameters:
len - the length of the input.
Returns:
the space required to accommodate a call to update and doFinal with len bytes of input.

getUnderlyingCipher

public BlockCipher getUnderlyingCipher()
return the cipher this object wraps.
Returns:
the cipher this object wraps.

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.

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.

processByte

public int processByte(byte in,
                       byte[] out,
                       int outOff)
            throws DataLengthException,
                   IllegalStateException
process a single byte, producing an output block if neccessary.
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.

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.

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).