java.lang.Object
- it.ipzs.cieid.AESFast

```
public class AESFast
extends java.lang.Object
```
an implementation of the AES (Rijndael), from FIPS-197.
For further details see: http://csrc.nist.gov/encryption/aes/. This implementation is based on optimizations from Dr. Brian Gladman's paper and C code at http://fp.gladman.plus.com/cryptography_technology/rijndael/ There are three levels of tradeoff of speed vs memory Because java has no preprocessor, they are written as three separate classes from which to choose The fastest uses 8Kbytes of static tables to precompute round calculations, 4 256 word tables for encryption and 4 for decryption. The middle performance version uses only one 256 word table for each, for a total of 2Kbytes, adding 12 rotate operations per round to compute the values contained in the other tables from the contents of the first The slowest version uses no static tables at all and computes the values in each round
This file contains the fast version with 8Kbytes of static tables for round precomputation

Nested Class Summary

Nested Classes
Modifier and Type Class Description

class AESFast.AESException

Field Summary

Fields
Modifier and Type	Field	Description
`private static int`	`BLOCK_SIZE`
`static int`	`BLOCK_SIZE_128`
`private int`	`C0`
`private int`	`C1`
`private int`	`C2`
`private int`	`C3`
`private boolean`	`forEncryption`
`static int`	`KEY_SIZE_128`
`static int`	`KEY_SIZE_160`
`static int`	`KEY_SIZE_192`
`static int`	`KEY_SIZE_224`
`static int`	`KEY_SIZE_256`
`private static int`	`m1`
`private static int`	`m2`
`private static int`	`m3`
`private static int[]`	`rcon`
`private int`	`ROUNDS`
`private static byte[]`	`S`
`private static byte[]`	`Si`
`private static int[]`	`T0`
`private static int[]`	`T1`
`private static int[]`	`T2`
`private static int[]`	`T3`
`private static int[]`	`Tinv0`
`private static int[]`	`Tinv1`
`private static int[]`	`Tinv2`
`private static int[]`	`Tinv3`
`private int[][]`	`WorkingKey`

Constructor Summary

Constructors
Constructor Description

AESFast()
default constructor - 128 bit block size.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`private void`	`decryptBlock(int[][] KW)`
`byte[]`	`decryptCBC(byte[] ciphertext, int nOffset, byte[] iv)`
`static byte[]`	`decryptCBC(byte[] ciphertext, int nOffset, byte[] key, int keylen, byte[] iv, int nBlockLen)`	Encrypt a palintext.
`byte[]`	`decryptECB(byte[] ciphertext, int nOffset)`	Encrypt a palintext.
`static byte[]`	`decryptECB(byte[] ciphertext, int nOffset, byte[] key, int keylen, int nBlockLen)`	Decrypt a ciphertext.
`private void`	`encryptBlock(int[][] KW)`
`private int`	`FFmulX(int x)`
`private int[][]`	`generateWorkingKey(byte[] key, boolean forEncryption)`	Calculate the necessary round keys The number of calculations depends on key size and block size AES specified a fixed block size of 128 bits and key sizes 128/192/256 bits This code is written assuming those are the only possible values
`java.lang.String`	`getAlgorithmName()`
`int`	`getBlockSize()`
`void`	`init(boolean forEncryption, byte[] key)`	initialise an AES cipher.
`private int`	`inv_mcol(int x)`
`static byte[]`	`makeSafeKey(byte[] k, int keysize)`
`private void`	`packBlock(byte[] bytes, int off)`
`int`	`processBlock(byte[] in, int inOff, byte[] out, int outOff)`
`void`	`reset()`
`private int`	`shift(int r, int shift)`
`private int`	`subWord(int x)`
`private void`	`unpackBlock(byte[] bytes, int off)`
`private byte[]`	`unpad(byte[] plaintext)`
`private void`	`xor(byte[] block, int offsetblok, byte[] iv, int offsetiv, byte[] xoredblock, int offserxored, int blocklen)`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

KEY_SIZE_256
```
public static final int KEY_SIZE_256
```
See Also:

Constant Field Values

KEY_SIZE_224
```
public static final int KEY_SIZE_224
```
See Also:

Constant Field Values

KEY_SIZE_160
```
public static final int KEY_SIZE_160
```
See Also:

Constant Field Values

KEY_SIZE_192
```
public static final int KEY_SIZE_192
```
See Also:

Constant Field Values

KEY_SIZE_128
```
public static final int KEY_SIZE_128
```
See Also:

Constant Field Values

BLOCK_SIZE_128
```
public static final int BLOCK_SIZE_128
```
See Also:

Constant Field Values

S
```
private static final byte[] S
```

Si
```
private static final byte[] Si
```

rcon
```
private static final int[] rcon
```

T0
```
private static final int[] T0
```

T1
```
private static final int[] T1
```

T2
```
private static final int[] T2
```

T3
```
private static final int[] T3
```

Tinv0
```
private static final int[] Tinv0
```

Tinv1
```
private static final int[] Tinv1
```

Tinv2
```
private static final int[] Tinv2
```

Tinv3
```
private static final int[] Tinv3
```

m1
```
private static final int m1
```
See Also:

Constant Field Values

m2
```
private static final int m2
```
See Also:

Constant Field Values

m3
```
private static final int m3
```
See Also:

Constant Field Values

ROUNDS
```
private int ROUNDS
```

WorkingKey
```
private int[][] WorkingKey
```

C0
```
private int C0
```

C1
```
private int C1
```

C2
```
private int C2
```

C3
```
private int C3
```

forEncryption
```
private boolean forEncryption
```

BLOCK_SIZE
```
private static final int BLOCK_SIZE
```
See Also:

Constant Field Values

Constructor Detail
- AESFast
```
public AESFast()
```
  default constructor - 128 bit block size.

Method Detail

shift

private int shift(int r,
                  int shift)

FFmulX
```
private int FFmulX(int x)
```

inv_mcol
```
private int inv_mcol(int x)
```

subWord
```
private int subWord(int x)
```

generateWorkingKey
```
private int[][] generateWorkingKey(byte[] key,
                                   boolean forEncryption)
```
Calculate the necessary round keys The number of calculations depends on key size and block size AES specified a fixed block size of 128 bits and key sizes 128/192/256 bits This code is written assuming those are the only possible values

init
```
public void init(boolean forEncryption,
                 byte[] key)
```
initialise an AES cipher.

Parameters:

forEncryption - whether or not we are for encryption.

params - the parameters required to set up the cipher.

Throws:

java.lang.IllegalArgumentException - if the params argument is inappropriate.

getAlgorithmName

public java.lang.String getAlgorithmName()

getBlockSize
```
public int getBlockSize()
```

processBlock

public int processBlock(byte[] in,
                        int inOff,
                        byte[] out,
                        int outOff)

reset
```
public void reset()
```

unpackBlock

private final void unpackBlock(byte[] bytes,
                               int off)

packBlock

private final void packBlock(byte[] bytes,
                             int off)

encryptBlock

private final void encryptBlock(int[][] KW)

decryptBlock

private final void decryptBlock(int[][] KW)

decryptECB
```
public byte[] decryptECB(byte[] ciphertext,
                         int nOffset)
```
Encrypt a palintext.

Parameters:

ciphertext - The ciphertext.

nOffset - Index of in from which to start considering data.

sessionKey - The session key to use for encryption.

blockSize - The block size in bytes of this Rijndael.

Returns:

The plaintext generated from ciphertext using the session key.

decryptCBC

public byte[] decryptCBC(byte[] ciphertext,
                         int nOffset,
                         byte[] iv)

unpad

private byte[] unpad(byte[] plaintext)

xor

private void xor(byte[] block,
                 int offsetblok,
                 byte[] iv,
                 int offsetiv,
                 byte[] xoredblock,
                 int offserxored,
                 int blocklen)

decryptECB
```
public static byte[] decryptECB(byte[] ciphertext,
                                int nOffset,
                                byte[] key,
                                int keylen,
                                int nBlockLen)
```
Decrypt a ciphertext.

Parameters:

ciphertext - The ciphertext.

nOffset - Index of in from which to start considering data.

key - The session key to use for encryption.

blockSize - The block size in bytes of this Rijndael.

Returns:

The plaintext generated from ciphertext using the session key.

decryptCBC
```
public static byte[] decryptCBC(byte[] ciphertext,
                                int nOffset,
                                byte[] key,
                                int keylen,
                                byte[] iv,
                                int nBlockLen)
```
Encrypt a palintext.

Parameters:

ciphertext - The ciphertext.

nOffset - Index of in from which to start considering data.

key - The session key to use for encryption.

blockSize - The block size in bytes of this Rijndael.

Returns:

The plaintext generated from ciphertext using the session key.

makeSafeKey

public static byte[] makeSafeKey(byte[] k,
                                 int keysize)

Class AESFast

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

KEY_SIZE_256

KEY_SIZE_224

KEY_SIZE_160

KEY_SIZE_192

KEY_SIZE_128

BLOCK_SIZE_128

S

Si

rcon

T0

T1

T2

T3

Tinv0

Tinv1

Tinv2

Tinv3

m1

m2

m3

ROUNDS

WorkingKey

C0

C1

C2

C3

forEncryption

BLOCK_SIZE

Constructor Detail

AESFast

Method Detail

shift

FFmulX

inv_mcol

subWord

generateWorkingKey

init

getAlgorithmName

getBlockSize

processBlock

reset

unpackBlock

packBlock

encryptBlock

decryptBlock

decryptECB

decryptCBC

unpad

xor

decryptECB

decryptCBC

makeSafeKey