gnu.crypto.cipher
Class DES
- Cloneable, IBlockCipher, IBlockCipherSpi
The Data Encryption Standard. DES is a 64-bit block cipher with a 56-bit
key, developed by IBM in the 1970's for the standardization process begun by
the National Bureau of Standards (now NIST).
New applications should not use DES except for compatibility.
This version is based upon the description and sample implementation in
[1].
References:
- Bruce Schneier, Applied Cryptography: Protocols, Algorithms, and
Source Code in C, Second Edition. (1996 John Wiley and Sons) ISBN
0-471-11709-9. Pages 265--301, 623--632.
Version:
(package private) class | DES.Context - Simple wrapper class around the session keys.
|
static int | BLOCK_SIZE - DES operates on 64 bit blocks.
|
static int | KEY_SIZE - DES uses 56 bits of a 64 bit parity-adjusted key.
|
static byte[][] | POSSIBLE_WEAK_KEYS - Possible weak keys (parity adjusted) --produce 4 instead of 16 subkeys.
|
static byte[][] | SEMIWEAK_KEYS - Semi-weak keys (parity adjusted): Some pairs of keys encrypt plain text
to identical cipher text.
|
static byte[][] | WEAK_KEYS - Weak keys (parity adjusted): If all the bits in each half are either 0
or 1, then the key used for any cycle of the algorithm is the same as
all other cycles.
|
DES() - Default 0-argument constructor.
|
static void | adjustParity(byte[] kb, int offset) - Adjust the parity for a raw key array.
|
Iterator | blockSizes() - Returns an
java.util.Iterator over the supported block sizes.
|
Object | clone()
|
void | decrypt(byte[] in, int i, byte[] out, int o, Object K, int bs) - Decrypts exactly one block of ciphertext.
|
void | encrypt(byte[] in, int i, byte[] out, int o, Object K, int bs) - Encrypts exactly one block of plaintext.
|
static boolean | isParityAdjusted(byte[] kb, int offset) - Test if a byte array, which must be at least 8 bytes long, is parity
adjusted.
|
static boolean | isPossibleWeak(byte[] kb) - Test if the designated byte array represents a possibly weak key.
|
static boolean | isSemiWeak(byte[] kb) - Test if a key is a semi-weak key.
|
static boolean | isWeak(byte[] kb) - Test if a key is a weak key.
|
Iterator | keySizes() - Returns an
java.util.Iterator over the supported key sizes.
|
Object | makeKey(byte[] kb, int bs) - Expands a user-supplied key material into a session key for a
designated block size.
|
clone , currentBlockSize , decryptBlock , defaultBlockSize , defaultKeySize , encryptBlock , init , name , reset , selfTest , testKat , testKat |
BLOCK_SIZE
public static final int BLOCK_SIZE
DES operates on 64 bit blocks.
- 8
KEY_SIZE
public static final int KEY_SIZE
DES uses 56 bits of a 64 bit parity-adjusted key.
- 8
POSSIBLE_WEAK_KEYS
public static final byte[][] POSSIBLE_WEAK_KEYS
Possible weak keys (parity adjusted) --produce 4 instead of 16 subkeys.
SEMIWEAK_KEYS
public static final byte[][] SEMIWEAK_KEYS
Semi-weak keys (parity adjusted): Some pairs of keys encrypt plain text
to identical cipher text. In other words, one key in the pair can decrypt
messages that were encrypted with the other key. These keys are called
semi-weak keys. This occurs because instead of 16 different sub-keys being
generated, these semi-weak keys produce only two different sub-keys.
WEAK_KEYS
public static final byte[][] WEAK_KEYS
Weak keys (parity adjusted): If all the bits in each half are either 0
or 1, then the key used for any cycle of the algorithm is the same as
all other cycles.
DES
public DES()
Default 0-argument constructor.
adjustParity
public static void adjustParity(byte[] kb,
int offset)
Adjust the parity for a raw key array. This essentially means that each
byte in the array will have an odd number of '1' bits (the last bit in
each byte is unused.
kb
- The key array, to be parity-adjusted.offset
- The starting index into the key bytes.
blockSizes
public Iterator blockSizes()
Returns an java.util.Iterator
over the supported block sizes.
Each element returned by this object is a java.lang.Integer
.
- blockSizes in interface IBlockCipher
- blockSizes in interface IBlockCipherSpi
- an
Iterator
over the supported block sizes.
decrypt
public void decrypt(byte[] in,
int i,
byte[] out,
int o,
Object K,
int bs)
Decrypts exactly one block of ciphertext.
- decrypt in interface IBlockCipherSpi
in
- the ciphertext.out
- the plaintext.bs
- the block size to use.
encrypt
public void encrypt(byte[] in,
int i,
byte[] out,
int o,
Object K,
int bs)
Encrypts exactly one block of plaintext.
- encrypt in interface IBlockCipherSpi
in
- the plaintext.out
- the ciphertext.bs
- the block size to use.
isParityAdjusted
public static boolean isParityAdjusted(byte[] kb,
int offset)
Test if a byte array, which must be at least 8 bytes long, is parity
adjusted.
kb
- The key bytes.offset
- The starting index into the key bytes.
true
if the first 8 bytes of kb have been
parity adjusted. false
otherwise.
isPossibleWeak
public static boolean isPossibleWeak(byte[] kb)
Test if the designated byte array represents a possibly weak key.
kb
- the byte array to test.
true
if kb
represents a possibly weak key.
Returns false
otherwise.
isSemiWeak
public static boolean isSemiWeak(byte[] kb)
Test if a key is a semi-weak key.
kb
- The key to test.
true
if this key is semi-weak.
isWeak
public static boolean isWeak(byte[] kb)
Test if a key is a weak key.
kb
- The key to test.
true
if the key is weak.
keySizes
public Iterator keySizes()
Returns an java.util.Iterator
over the supported key sizes.
Each element returned by this object is a java.lang.Integer
.
- keySizes in interface IBlockCipher
- keySizes in interface IBlockCipherSpi
- an
Iterator
over the supported key sizes.
makeKey
public Object makeKey(byte[] kb,
int bs)
throws InvalidKeyException
Expands a user-supplied key material into a session key for a
designated block size.
- makeKey in interface IBlockCipherSpi
bs
- the desired block size in bytes.
- an Object encapsulating the session key.
Copyright © 2001, 2002, 2003
Free Software Foundation,
Inc. All Rights Reserved.