edu.vt.middleware.crypt.symmetric
Class RC4

java.lang.Object
  edu.vt.middleware.crypt.AbstractAlgorithm
      edu.vt.middleware.crypt.AbstractEncryptionAlgorithm
          edu.vt.middleware.crypt.symmetric.SymmetricAlgorithm
              edu.vt.middleware.crypt.symmetric.RC4

All Implemented Interfaces:

Algorithm, EncryptionAlgorithm

public class RC4
extends SymmetricAlgorithm

Provider of symmetric encryption/decryption operations using RC4 cipher.

Version:

$Revision: 2744 $

Author:

Middleware Services

Field Summary

static String	ALGORITHM Algorithm name.
static int[]	KEY_LENGTHS Available key lengths in bits.

Fields inherited from class edu.vt.middleware.crypt.symmetric.SymmetricAlgorithm

DEFAULT_MODE, DEFAULT_PADDING, iv, paramSpec

Fields inherited from class edu.vt.middleware.crypt.AbstractEncryptionAlgorithm

cipher, cipherMode, key, mode, padding

Fields inherited from class edu.vt.middleware.crypt.AbstractAlgorithm

algorithm, logger, randomByteSize, randomProvider

Constructor Summary

RC4()
Creates a RC4 symmetric encryption algorithm.

RC4(String mode, String padding)
Creates a RC4 symmetric encryption algorithm.

Method Summary

int[]	getAllowedKeyLengths() Gets an array of key lengths that are acceptable for the cipher algorithm.
boolean	isValidKeyLength(int bitLength) Determines whether the given key size in bits is valid for this symmetric cipher algorithm.
void	setIV(byte[] ivBytes) Sets the encryption initialization vector.

Methods inherited from class edu.vt.middleware.crypt.symmetric.SymmetricAlgorithm

clone, getAlgorithmParameterSpec, getChunkSize, getMaxKeyLength, getMinKeyLength, getRandomIV, hasIV, newInstance, newInstance, newInstance, newInstance

Methods inherited from class edu.vt.middleware.crypt.AbstractEncryptionAlgorithm

crypt, crypt, decrypt, decrypt, decrypt, encrypt, encrypt, encrypt, getBlockSize, getCipherMode, getMode, getPadding, init, initCipher, initDecrypt, initEncrypt, setKey, toString

Methods inherited from class edu.vt.middleware.crypt.AbstractAlgorithm

getAlgorithm, getRandomData, setRandomProvider

Methods inherited from class java.lang.Object

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

Methods inherited from interface edu.vt.middleware.crypt.Algorithm

getAlgorithm, getRandomData, setRandomProvider

Field Detail

ALGORITHM

public static final String ALGORITHM

Algorithm name.

See Also:

Constant Field Values

KEY_LENGTHS

public static final int[] KEY_LENGTHS

Available key lengths in bits.

Constructor Detail

RC4

public RC4()

Creates a RC4 symmetric encryption algorithm.

RC4

public RC4(String mode,
           String padding)

Creates a RC4 symmetric encryption algorithm. The mode and padding arguments are ignored since this is a stream cipher and does not support a block mode or padding; it is provided for consistency with other ciphers only.

Parameters:

mode - Cipher mode name -- ignored.

padding - Cipher padding style name -- ignored.

Method Detail

setIV

public void setIV(byte[] ivBytes)

Sets the encryption initialization vector. A unique IV should be specified for each encryption operation using the same key for good security. Use the SymmetricAlgorithm.getRandomIV() method to obtain random initialization data of the appropriate size for the chosen cipher.

IV data is used upon calling either AbstractEncryptionAlgorithm.initEncrypt() or AbstractEncryptionAlgorithm.initDecrypt().

Overrides:

setIV in class SymmetricAlgorithm

Parameters:

ivBytes - Initialization bytes; in many cases the size of data should be equal to the cipher block size.

getAllowedKeyLengths

public int[] getAllowedKeyLengths()

Gets an array of key lengths that are acceptable for the cipher algorithm. By convention the lengths are returned in descending sort order from longest to shortest. There are some ciphers (e.g. Blowfish) that allow key sizes to be any integral value in a range; in those cases only key sizes that are multiple of the cipher block length are returned. Thus this method always returns lengths that are acceptable, but not necessarily all possible lengths.

Overrides:

getAllowedKeyLengths in class SymmetricAlgorithm

Returns:

Array of key lengths in bits.

isValidKeyLength

public boolean isValidKeyLength(int bitLength)

Determines whether the given key size in bits is valid for this symmetric cipher algorithm.

Overrides:

isValidKeyLength in class SymmetricAlgorithm

Parameters:

bitLength - Key size in bits.

Returns:

True if given value is a valid key size for this algorithm, false otherwise.