org.bouncycastle.crypto.paddings

Class PaddedBufferedBlockCipher

public class PaddedBufferedBlockCipher extends BufferedBlockCipher

A wrapper class that allows block ciphers to be used to process data in a piecemeal fashion with padding. The PaddedBufferedBlockCipher 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 default padding mechanism used is the one outlined in PKCS5/PKCS7.
Constructor Summary
PaddedBufferedBlockCipher(BlockCipher cipher, BlockCipherPadding padding)
Create a buffered block cipher with the desired padding.
PaddedBufferedBlockCipher(BlockCipher cipher)
Create a buffered block cipher PKCS7 padding
Method Summary
intdoFinal(byte[] out, int outOff)
Process the last block in the buffer.
intgetOutputSize(int len)
return the minimum size of the output buffer required for an update plus a doFinal with an input of len bytes.
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.

Constructor Detail

PaddedBufferedBlockCipher

public PaddedBufferedBlockCipher(BlockCipher cipher, BlockCipherPadding padding)
Create a buffered block cipher with the desired padding.

Parameters: cipher the underlying block cipher this buffering object wraps. padding the padding type.

PaddedBufferedBlockCipher

public PaddedBufferedBlockCipher(BlockCipher cipher)
Create a buffered block cipher PKCS7 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. If the buffer is currently full and padding needs to be added a call to doFinal will produce 2 * getBlockSize() bytes.

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 we are decrypting and the input is not block size aligned. IllegalStateException if the underlying cipher is not initialised. InvalidCipherTextException if padding is expected and not found.

getOutputSize

public int getOutputSize(int len)
return the minimum 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.

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.