org.bouncycastle.crypto.modes

Class CTSBlockCipher

public class CTSBlockCipher extends BufferedBlockCipher

A Cipher Text Stealing (CTS) mode cipher. CTS allows block ciphers to be used to produce cipher text which is the same length as the plain text.
Constructor Summary
CTSBlockCipher(BlockCipher cipher)
Create a buffered block cipher that uses Cipher Text Stealing
Method Summary
intdoFinal(byte[] out, int outOff)
Process the last block in the buffer.
intgetOutputSize(int len)
return the 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.
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

CTSBlockCipher

public CTSBlockCipher(BlockCipher cipher)
Create a buffered block cipher that uses Cipher Text Stealing

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. IllegalStateException if the underlying cipher is not initialised. InvalidCipherTextException if cipher text decrypts wrongly (in case the exception will never get thrown).

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.

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.

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.