gnu.crypto.cipher
public class DES extends BaseCipher
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:
Version: $Revision: 1.4 $
Nested Class Summary | |
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class | DES.Context
Simple wrapper class around the session keys. |
Field Summary | |
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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. |
Constructor Summary | |
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DES() Default 0-argument constructor. |
Method Summary | |
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static void | adjustParity(byte[] kb, int offset) Adjust the parity for a raw key array. |
Iterator | blockSizes() |
Object | clone() |
void | decrypt(byte[] in, int i, byte[] out, int o, Object K, int bs) |
void | encrypt(byte[] in, int i, byte[] out, int o, Object K, int bs) |
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() |
Object | makeKey(byte[] kb, int bs) |
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.
Parameters: kb The key array, to be parity-adjusted. offset The starting index into the key bytes.
Test if a byte array, which must be at least 8 bytes long, is parity adjusted.
Parameters: kb The key bytes. offset The starting index into the key bytes.
Returns: true
if the first 8 bytes of kb have been
parity adjusted. false
otherwise.
Test if the designated byte array represents a possibly weak key.
Parameters: kb the byte array to test.
Returns: true
if kb
represents a possibly weak key.
Returns false
otherwise.
Test if a key is a semi-weak key.
Parameters: kb The key to test.
Returns: true
if this key is semi-weak.
Test if a key is a weak key.
Parameters: kb The key to test.
Returns: true
if the key is weak.