de.uniks.networkparser.bytes.checksum

Class AES

java.lang.Object

de.uniks.networkparser.bytes.checksum.AES

public class AES
extends java.lang.Object

AES - implementation of the AES block cipher in Java.

Illustrative code for the AES block cipher (Rijndael). Handles a single block encryption or decryption, with diagnostic logging of intermediate values if required.

AES is a block cipher with a key length of 16/24/32 bytes and a block length 16 bytes.

AES (Rijndael) was designed by Joan Daemen and Vincent Rijmen, and was accepted as the US NIST's Advanced Encryption Standard in 2000.

This is the slow, obvious code version, written to follow the algorithm specification as closely and clearly as possible. It's code was originally derived from the illustrative Rijndael Java implementation submitted to the AES process, and sourced from the Rijndael sample Java code, but has been extensively adapted by Lawrie Brown to suit the illustrative requirements of the crypto calc applets he has written for his Cryptography courses at ADFA. The code has been tested using the AES triples published in FIPS-197 App C.

See Also:

Lawrie Brown, AES home page, FIPS-197 Standard, Rijndael Home Page, Rijndael example Java code

Field Summary

Fields

Modifier and Type	Field and Description
static int	BLOCK_SIZE AES constants and variables.
static int	COL_SIZE Internal AES constants and variables.
static int	KEY_LENGTH AES constants and variables.
static int	NUM_COLS Internal AES constants and variables.
static int	ROOT Internal AES constants and variables.
static int	ROUNDS AES constants and variables.

Constructor Summary

Constructors

Constructor and Description
AES()

Method Summary

Modifier and Type	Method and Description
CharacterBuffer	decode(java.lang.String data)
byte[]	decodeBlock(byte[] cipher) AES decrypt 128-bit ciphertext using key previously set.
byte[]	decodeBlock(char[] plain, int from) AES encrypt 128-bit plaintext using key previously set.
byte[]	decodeString(java.lang.String value)
CharacterBuffer	encode(BufferedBuffer plain)
CharacterBuffer	encode(java.lang.String data)
byte[]	encodeBlock(byte[] plain) AES encrypt 128-bit plaintext using key previously set.
byte[]	encodeBlock(char[] plain, int from) AES encrypt 128-bit plaintext using key previously set.
static int	getRounds(int keySize) return number of rounds for a given AES key size.
void	setKey(byte[] key) Expand a user-supplied key material into a session key.
void	setKey(java.lang.String key)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

ROUNDS

public static final int ROUNDS

AES constants and variables.

See Also:

Constant Field Values

BLOCK_SIZE

public static final int BLOCK_SIZE

AES constants and variables.

See Also:

Constant Field Values

KEY_LENGTH

public static final int KEY_LENGTH

AES constants and variables.

See Also:

Constant Field Values

COL_SIZE

public static final int COL_SIZE

Internal AES constants and variables.

See Also:

Constant Field Values

NUM_COLS

public static final int NUM_COLS

Internal AES constants and variables.

See Also:

Constant Field Values

ROOT

public static final int ROOT

Internal AES constants and variables.

See Also:

Constant Field Values

Constructor Detail

AES

public AES()

Method Detail

getRounds

public static int getRounds(int keySize)

return number of rounds for a given AES key size.

Parameters:

keySize - size of the user key material in bytes.

Returns:

number of rounds for a given AES key size.

encode

public CharacterBuffer encode(BufferedBuffer plain)

encode

public CharacterBuffer encode(java.lang.String data)

encodeBlock

public byte[] encodeBlock(char[] plain,
                          int from)

AES encrypt 128-bit plaintext using key previously set.

Follows cipher specification given in FIPS-197 section 5.1 See pseudo code in Fig 5, and details in this section.

Parameters:

plain - the 128-bit plaintext value to encrypt.

from - fromIndex of Array

Returns:

the encrypted 128-bit ciphertext value.

encodeBlock

public byte[] encodeBlock(byte[] plain)

AES encrypt 128-bit plaintext using key previously set.

Follows cipher specification given in FIPS-197 section 5.1 See pseudo code in Fig 5, and details in this section.

Parameters:

plain - the 128-bit plaintext value to encrypt.

Returns:

the encrypted 128-bit ciphertext value.

decode

public CharacterBuffer decode(java.lang.String data)

decodeString

public byte[] decodeString(java.lang.String value)

decodeBlock

public byte[] decodeBlock(char[] plain,
                          int from)

AES encrypt 128-bit plaintext using key previously set.

Follows cipher specification given in FIPS-197 section 5.1 See pseudo code in Fig 5, and details in this section.

Parameters:

plain - the 128-bit plaintext value to encrypt.

from - fromIndex of Array

Returns:

the encrypted 128-bit ciphertext value.

decodeBlock

public byte[] decodeBlock(byte[] cipher)

AES decrypt 128-bit ciphertext using key previously set.

Follows cipher specification given in FIPS-197 section 5.3 See pseudo code in Fig 5, and details in this section.

Parameters:

cipher - the 128-bit ciphertext value to decrypt.

Returns:

the decrypted 128-bit plaintext value.

setKey

public void setKey(java.lang.String key)

setKey

public void setKey(byte[] key)
            throws java.lang.IllegalArgumentException

Expand a user-supplied key material into a session key.

See FIPS-197 Section 5.3 Fig 11 for details of the key expansion.

Session keys will be saved in Ke and Kd instance variables, along with numRounds being the number of rounds for this sized key.

Parameters:

key - The 128/192/256-bit AES key to use.

Throws:

java.lang.IllegalArgumentException