public class

BufferedBlockCipher

extends Object
java.lang.Object
   ↳ org.bouncycastle.crypto.BufferedBlockCipher
Known Direct Subclasses

Class Overview

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.

Summary

Fields
protected byte[] buf
protected int bufOff
protected BlockCipher cipher
protected boolean forEncryption
protected boolean partialBlockOkay
protected boolean pgpCFB
Public Constructors
BufferedBlockCipher(BlockCipher cipher)
Create a buffered block cipher without padding.
Protected Constructors
BufferedBlockCipher()
constructor for subclasses
Public Methods
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 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.
[Expand]
Inherited Methods
From class java.lang.Object

Fields

protected byte[] buf

protected int bufOff

protected BlockCipher cipher

protected boolean forEncryption

protected boolean partialBlockOkay

protected boolean pgpCFB

Public Constructors

public BufferedBlockCipher (BlockCipher cipher)

Create a buffered block cipher without padding.

Parameters
cipher the underlying block cipher this buffering object wraps.

Protected Constructors

protected BufferedBlockCipher ()

constructor for subclasses

Public Methods

public int doFinal (byte[] out, int outOff)

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.

public int getBlockSize ()

return the blocksize for the underlying cipher.

Returns
  • the blocksize for the underlying cipher.

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.

public BlockCipher getUnderlyingCipher ()

return the cipher this object wraps.

Returns
  • the cipher this object wraps.

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.

public void init (boolean forEncryption, CipherParameters params)

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.

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

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.
IllegalStateException if the cipher isn't initialised.

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

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.

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).