public class CTR extends BaseMode implements java.lang.Cloneable
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] ^ O[j]; for j = 1, 2...n. CTR Decryption: O[j] = E(K)(T[j]); for j = 1, 2...n; P[j] = C[j] ^ 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:
algorithmParams, cipher, cipherBlockSize, iv, lock, modeBlockSize, name, state
ALGORITHM_PARAMS, DECRYPTION, ENCRYPTION, IV, MODE_BLOCK_SIZE, STATE
CIPHER_BLOCK_SIZE, KEY_MATERIAL
Modifier and Type | Method and Description |
---|---|
java.lang.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, currentBlockSize, defaultBlockSize, defaultKeySize, init, keySizes, name, reset, selfTest, update
public java.lang.Object clone()
IBlockCipher
Returns a clone of this instance.
clone
in interface IBlockCipher
clone
in class BaseMode
public void setup()
BaseMode
public void teardown()
BaseMode
public void encryptBlock(byte[] in, int i, byte[] out, int o)
IBlockCipher
Encrypts exactly one block of plaintext.
encryptBlock
in interface IBlockCipher
encryptBlock
in class BaseMode
in
- the plaintext.i
- index of in
from which to start considering
data.out
- the ciphertext.o
- index of out
from which to store result.public void decryptBlock(byte[] in, int i, byte[] out, int o)
IBlockCipher
Decrypts exactly one block of ciphertext.
decryptBlock
in interface IBlockCipher
decryptBlock
in class BaseMode
in
- the plaintext.i
- index of in
from which to start considering
data.out
- the ciphertext.o
- index of out
from which to store result.Copyright © 2025. All rights reserved.