cryptix.provider.cipher
Class DES
- Parameterized, SymmetricCipher
DES is a block cipher with an 8 byte block size. The key length
is 8 bytes, but only 56 bits are used as the parity bit in each
byte is ignored.
This algorithm has been seriously analysed over the last 30 years,
and no significant weaknesses have been reported. Its only known
flaw is that the key length of 56 bits makes it relatively easy to
brute-force it.
To overcome this near-fatal flaw, it is recommended that DES be
used in Triple DES mode. The JCA algorithm name for the recommended
form of Triple DES is "DES-EDE3/CBC", which is implemented by the
DES_EDE3
and
CBC
DES was written by IBM and first released in 1976. The algorithm is
freely usable for both single and triple encryption.
References:
- Bruce Schneier,
"Chapter 12 Data Encryption Standard,"
Applied Cryptography, 2nd edition,
John Wiley & Sons, 1996.
- NIST FIPS PUB 46-2 (supercedes FIPS PUB 46-1),
"Data Encryption Standard",
U.S. Department of Commerce, December 1993.
http://www.itl.nist.gov/div897/pubs/fip46-2.htm
Copyright © 1997
Systemics Ltd on behalf of the
Cryptix Development Team.
All rights reserved.
$Revision: 1.6 $
- Systemics Ltd
- Geoffrey Keating (this Java implementation)
- Eric Young
- David Hopwood
- Raif S. Naffah
- John F. Dumas (jdumas@zgs.com)
- Cryptix 2.2.2
DES() - Constructs a DES cipher object, in the UNINITIALIZED state.
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Object | clone() - Always throws a CloneNotSupportedException (cloning of ciphers is not
supported for security reasons).
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int[] | crypt3(int E0, int E1) - Implements the Unix crypt(3) algorithm.
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protected void | des(byte[] in, int inOffset, byte[] out, int outOffset, boolean encrypt) - Encrypts/decrypts a block, of length BLOCK_SIZE.
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int | engineBlockSize() - SPI: Returns the length of an input block, in bytes.
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void | engineInitDecrypt(Key key) - SPI: Initializes this cipher for decryption, using the
specified key.
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void | engineInitEncrypt(Key key) - SPI: Initializes this cipher for encryption, using the
specified key.
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protected int | engineUpdate(byte[] in, int inOffset, int inLen, byte[] out, int outOffset) - SPI: This is the main engine method for updating data.
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protected void | finalize() - Cleans up resources used by this instance, if necessary.
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static LinkStatus | getLinkStatus() - Gets an object representing the native linking status of this class.
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static void | main(String[] argv) - Entry point for
self_test .
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blockSize , clone , crypt , crypt , crypt , doFinal , doFinal , doFinal , doFinal , engineBlockSize , engineCiphertextBlockSize , engineCrypt , engineGetParameter , engineInBufferSize , engineInitDecrypt , engineInitEncrypt , engineOutBufferSize , enginePlaintextBlockSize , engineSetPaddingScheme , engineSetParameter , engineUpdate , getAlgorithm , getAlgorithms , getAlgorithms , getCiphertextBlockSize , getInputBlockSize , getInstance , getInstance , getInstance , getMode , getOutputBlockSize , getPadding , getPaddingScheme , getParameter , getPlaintextBlockSize , getProvider , getState , inBufferSize , inBufferSizeFinal , initDecrypt , initEncrypt , isPaddingBlockCipher , outBufferSize , outBufferSizeFinal , setParameter , toString , update , update , update , update |
DES
public DES()
Constructs a DES cipher object, in the UNINITIALIZED state.
This calls the Cipher constructor with implBuffering false,
implPadding false and the provider set to "Cryptix".
clone
public final Object clone()
throws CloneNotSupportedException
Always throws a CloneNotSupportedException (cloning of ciphers is not
supported for security reasons).
- clone in interface Cipher
crypt3
public int[] crypt3(int E0,
int E1)
Implements the Unix crypt(3) algorithm.
This method is intended only for use by the class
cryptix.tools.UnixCrypt,
and should not be used directly by applications.
E0
- first 32 bits of input.E1
- second 32 bits of input.
des
protected void des(byte[] in,
int inOffset,
byte[] out,
int outOffset,
boolean encrypt)
Encrypts/decrypts a block, of length BLOCK_SIZE.
in
- an array containing the input blockinOffset
- the starting offset of the input blockout
- an array containing the output blockencrypt
- true to encrypt, false to decrypt
engineBlockSize
public int engineBlockSize()
SPI: Returns the length of an input block, in bytes.
- engineBlockSize in interface Cipher
- the length in bytes of an input block for this cipher.
engineInitDecrypt
public void engineInitDecrypt(Key key)
throws InvalidKeyException,
CryptixException
SPI: Initializes this cipher for decryption, using the
specified key.
- engineInitDecrypt in interface Cipher
key
- the key to use for decryption.
engineInitEncrypt
public void engineInitEncrypt(Key key)
throws InvalidKeyException
SPI: Initializes this cipher for encryption, using the
specified key.
- engineInitEncrypt in interface Cipher
key
- the key to use for encryption.
engineUpdate
protected int engineUpdate(byte[] in,
int inOffset,
int inLen,
byte[] out,
int outOffset)
SPI: This is the main engine method for updating data.
in and
out may be the same array, and the input and output
regions may overlap.
- engineUpdate in interface Cipher
in
- the input data.inOffset
- the offset into in specifying where the data starts.inLen
- the length of the subarray.out
- the output array.outOffset
- the offset indicating where to start writing into
the out array.
- the number of bytes written.
finalize
protected final void finalize()
Cleans up resources used by this instance, if necessary.
getLinkStatus
public static LinkStatus getLinkStatus()
Gets an object representing the native linking status of this class.
main
public static void main(String[] argv)
Entry point for self_test
.