org.bouncycastle.crypto

Class BufferedBlockCipher

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
protected byte[]buf
protected intbufOff
protected BlockCiphercipher
protected booleanforEncryption
protected booleanpartialBlockOkay
protected booleanpgpCFB
Constructor Summary
protected BufferedBlockCipher()
constructor for subclasses
BufferedBlockCipher(BlockCipher cipher)
Create a buffered block cipher without padding.
Method Summary
intdoFinal(byte[] out, int outOff)
Process the last block in the buffer.
intgetBlockSize()
return the blocksize for the underlying cipher.
intgetOutputSize(int len)
return the size of the output buffer required for an update plus a doFinal with an input of len bytes.
BlockCiphergetUnderlyingCipher()
return the cipher this object wraps.
intgetUpdateOutputSize(int len)
return the size of the output buffer required for an update an input of len bytes.
voidinit(boolean forEncryption, CipherParameters params)
initialise the cipher.
intprocessByte(byte in, byte[] out, int outOff)
process a single byte, producing an output block if neccessary.
intprocessBytes(byte[] in, int inOff, int len, byte[] out, int outOff)
process an array of bytes, producing output if necessary.
voidreset()
Reset the buffer and cipher.

Field Detail

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 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

doFinal

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.

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)
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.

processByte

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.

processBytes

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.

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).