gnu.javax.crypto.mode
Class CTR
- Cloneable, IBlockCipher, IMode
The implementation of the Counter Mode.
The algorithm steps are formally described as follows:
CTR Encryption: O[j] = E(K)(T[j]); for j = 1, 2...n;
C[j] = P[j] ˆ O[j]; for j = 1, 2...n.
CTR Decryption: O[j] = E(K)(T[j]); for j = 1, 2...n;
P[j] = C[j] ˆ O[j]; for j = 1, 2...n.
where
P is the plaintext,
C is the ciphertext,
E(K) is the underlying block cipher encryption function
parametrised with the session key
K, and
T is
the
Counter.
This implementation, uses a standard incrementing function with a step of 1,
and an initial value similar to that described in the NIST document.
References:
-
Recommendation for Block Cipher Modes of Operation Methods and Techniques,
Morris Dworkin.
Iterator<E> | blockSizes()- Returns an
Iterator over the supported block sizes.
|
Object | clone()- Returns a clone of this instance.
|
void | decryptBlock(byte[] in, int i, byte[] out, int o)- Decrypts exactly one block of ciphertext.
|
void | encryptBlock(byte[] in, int i, byte[] out, int o)- Encrypts exactly one block of plaintext.
|
void | setup()- The initialisation phase of the concrete mode implementation.
|
void | teardown()- The termination phase of the concrete mode implementation.
|
blockSizes, clone, currentBlockSize, decryptBlock, defaultBlockSize, defaultKeySize, encryptBlock, init, keySizes, name, reset, selfTest, setup, teardown, update |
clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait |
blockSizes
public Iterator<E> blockSizes()
Returns an
Iterator over the supported block sizes. Each element
returned by this object is an
Integer.
The default behaviour is to return an iterator with just one value, which
is that currently configured for the underlying block cipher. Concrete
implementations may override this behaviour to signal their ability to
support other values.
- blockSizes in interface IBlockCipher
- blockSizes in interface BaseMode
- an
Iterator over the supported block sizes.
setup
public void setup()
The initialisation phase of the concrete mode implementation.
- setup in interface BaseMode
CTR.java --
Copyright (C) 2001, 2002, 2006 Free Software Foundation, Inc.
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