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gnu.javax.crypto.pad
Class TBC  view TBC download TBC.java

java.lang.Object
  extended bygnu.javax.crypto.pad.BasePad
      extended bygnu.javax.crypto.pad.TBC
All Implemented Interfaces:
IPad

public final class TBC
extends BasePad

The implementation of the Trailing Bit Complement (TBC) padding algorithm.

In this mode, "...the data string is padded at the trailing end with the complement of the trailing bit of the unpadded message: if the trailing bit is 1, then 0 bits are appended, and if the trailing bit is 0, then 1 bits are appended. As few bits are added as are necessary to meet the formatting size requirement."

References:
Recommendation for Block Cipher Modes of Operation Methods and Techniques, Morris Dworkin.


Field Summary
private static boolean DEBUG
           
private static int debuglevel
           
private static java.io.PrintWriter err
           
private static java.lang.String NAME
           
 
Fields inherited from class gnu.javax.crypto.pad.BasePad
blockSize, name
 
Constructor Summary
(package private) TBC()
          Trivial package-private constructor for use by the Factory class.
 
Method Summary
private static void debug(java.lang.String s)
           
 byte[] pad(byte[] in, int offset, int length)
          Returns the byte sequence that should be appended to the designated input.
 void setup()
          If any additional checks or resource setup must be done by the subclass, then this is the hook for it.
 int unpad(byte[] in, int offset, int length)
          Returns the number of bytes to discard from a designated input buffer.
 
Methods inherited from class gnu.javax.crypto.pad.BasePad
init, name, reset, selfTest
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

NAME

private static final java.lang.String NAME
See Also:
Constant Field Values

DEBUG

private static final boolean DEBUG
See Also:
Constant Field Values

debuglevel

private static final int debuglevel
See Also:
Constant Field Values

err

private static final java.io.PrintWriter err
Constructor Detail

TBC

TBC()
Trivial package-private constructor for use by the Factory class.

Method Detail

debug

private static void debug(java.lang.String s)

setup

public void setup()
Description copied from class: BasePad

If any additional checks or resource setup must be done by the subclass, then this is the hook for it. This method will be called before the BasePad.init(int) 55 method returns.

Specified by:
setup in class BasePad

pad

public byte[] pad(byte[] in,
                  int offset,
                  int length)
Description copied from interface: IPad
Returns the byte sequence that should be appended to the designated input.

Specified by:
pad in interface IPad
Specified by:
pad in class BasePad

unpad

public int unpad(byte[] in,
                 int offset,
                 int length)
          throws WrongPaddingException
Description copied from interface: IPad
Returns the number of bytes to discard from a designated input buffer.

Specified by:
unpad in interface IPad
Specified by:
unpad in class BasePad