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Class cryptix.provider.cipher.DES
java.lang.Object
|
+----java.security.IJCE_Traceable
|
+----java.security.Cipher
|
+----cryptix.provider.cipher.DES
- public final class DES
- extends Cipher
- implements 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: 1.5 $
- Author:
- Systemics Ltd, Geoffrey Keating (this Java implementation), Eric Young, David Hopwood, Raif S. Naffah, John F. Dumas (jdumas@zgs.com)
-
DES()
- Constructs a DES cipher object, in the UNINITIALIZED state.
-
clone()
- Always throws a CloneNotSupportedException (cloning of ciphers is not
supported for security reasons).
-
crypt3(int, int)
- Implements the Unix crypt(3) algorithm.
-
des(byte[], int, byte[], int, boolean)
- Encrypts/decrypts a block, of length BLOCK_SIZE.
-
engineBlockSize()
- SPI: Returns the length of an input block, in bytes.
-
engineInitDecrypt(Key)
- SPI: Initializes this cipher for decryption, using the
specified key.
-
engineInitEncrypt(Key)
- SPI: Initializes this cipher for encryption, using the
specified key.
-
engineUpdate(byte[], int, int, byte[], int)
- SPI: This is the main engine method for updating data.
-
finalize()
- Cleans up resources used by this instance, if necessary.
-
getLinkStatus()
- Gets an object representing the native linking status of this class.
-
main(String[])
- Entry point for
self_test
.
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".
getLinkStatus
public static LinkStatus getLinkStatus()
- Gets an object representing the native linking status of this class.
finalize
protected final void finalize()
- Cleans up resources used by this instance, if necessary.
- Overrides:
- finalize in class Object
clone
public final Object clone() throws CloneNotSupportedException
- Always throws a CloneNotSupportedException (cloning of ciphers is not
supported for security reasons).
- Overrides:
- clone in class Cipher
engineBlockSize
public int engineBlockSize()
- SPI: Returns the length of an input block, in bytes.
- Returns:
- the length in bytes of an input block for this cipher.
- Overrides:
- engineBlockSize in class Cipher
engineInitEncrypt
public void engineInitEncrypt(Key key) throws InvalidKeyException
- SPI: Initializes this cipher for encryption, using the
specified key.
- Parameters:
- key - the key to use for encryption.
- Throws: InvalidKeyException
- if one of the following occurs:
- key.getEncoded() == null;
- The length of the user key array is not KEY_LENGTH.
- Overrides:
- engineInitEncrypt in class Cipher
engineInitDecrypt
public void engineInitDecrypt(Key key) throws InvalidKeyException, CryptixException
- SPI: Initializes this cipher for decryption, using the
specified key.
- Parameters:
- key - the key to use for decryption.
- Throws: InvalidKeyException
- if one of the following occurs:
- key.getEncoded() == null;
- The length of the user key array is not KEY_LENGTH.
- Overrides:
- engineInitDecrypt in class Cipher
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.
- Parameters:
- 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.
- Returns:
- the number of bytes written.
- Throws: CryptixException
- if the native library is being used, and it
reports an error.
- Overrides:
- engineUpdate in class Cipher
des
protected void des(byte in[],
int inOffset,
byte out[],
int outOffset,
boolean encrypt)
- Encrypts/decrypts a block, of length BLOCK_SIZE.
- Parameters:
- in - an array containing the input block
- inOffset - the starting offset of the input block
- out - an array containing the output block
- inOffset - the starting offset of the output block
- encrypt - true to encrypt, false to decrypt
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.
- Parameters:
- E0 - first 32 bits of input.
- E1 - second 32 bits of input.
main
public static void main(String argv[])
- Entry point for
self_test
.
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