org.logi.crypto.keys
Class DESKey

java.lang.Object
  |
  +--org.logi.crypto.Crypto
        |
        +--org.logi.crypto.keys.K
              |
              +--org.logi.crypto.keys.SymmetricKey
                    |
                    +--org.logi.crypto.keys.DESKey

All Implemented Interfaces:

CipherKey, DecryptionKey, EncryptionKey, Key, java.security.Key, PrettyPrintable, java.io.Serializable

public class DESKey

extends org.logi.crypto.keys.SymmetricKey

implements CipherKey

This is the class for Data Encryption Standard (DES) keys. See FIPS PUB 46-1 or DEA defined in ANSI X3.92-1981 for a complete specification.

DES is the most widely used block cipher, although it is nowadays normally used repeatedly for each piece of plain-text and is called triple-DES. This is because the 56-bit key-size of the normal DES is too small to offer complete security.

The CDS for a DES key is DESKey(key) with key a string of 16 hexadecimal digits to create a specific key or DESKey(?) for a random DESKey object.

This implementation is done from the description given in Schneier's Applied Cryptography.

Author:

Logi Ragnarsson (logi@logi.org)

See Also:

TriDESKey, Serialized Form

Fields inherited from class org.logi.crypto.Crypto

BIT, cdsPath, EMPTY_ARRAY, FOUR, keySource, NIBBLE, ONE, primeCertainty, random, TWO, ZERO

Fields inherited from interface java.security.Key

serialVersionUID

Constructor Summary

DESKey()
Create a new random DES key.

DESKey(byte[] key)
Create a new DES key with the key bits from key[0..7].

DESKey(long key)
Create a new DES key with the key bits from key.

Method Summary

int	cipherBlockSize() The block-size for the DES cipher is 8 bytes.
void	decrypt(byte[] source, int i, byte[] dest, int j) Decrypt one block of data.
void	encrypt(byte[] source, int i, byte[] dest, int j) Encrypt one block of data.
boolean	equals(java.lang.Object o) Return true iff the two keys are equivalent.
java.lang.String	getAlgorithm() The name of the algorithm is "DES".
byte[]	getEncoded() Return encoded version.
Fingerprint	getFingerprint() Return the key's fingerprint using the default hash function.
Fingerprint	getFingerprint(java.lang.String algorithm) Return the key's fingerprint using the specified hash function.
java.lang.String	getFormat() Returns the name of the key-encoding format.
byte[]	getKey() Return the key-bits for this key as an array of 8 bytes.
int	getSize() The key-size for the DES cipher is 56 bits.
int	hashCode() Return a hash-code based on the keys SHA1 fingerprint.
boolean	matches(Key key) Returns true if this and key are the same symmetric key.
Fingerprint	matchFingerprint() Returns the default fingerprint of the matching key in the key-pair.
Fingerprint	matchFingerprint(java.lang.String algorithm) Returns the default fingerprint of the matching key in the key-pair.
static DESKey	parseCDS(java.lang.String[] param) Used by Crypto.fromString when parsing a CDS.
int	plainBlockSize() The block-size for the DES cipher is 8 bytes.
java.lang.String	toString() Return a CDS for this key.

Methods inherited from class org.logi.crypto.Crypto

binString, binString, ensureArrayLength, ensureArrayLength, equal, equalRelaxed, equalSub, fromHexNibble, fromHexString, fromString, fromString, hexString, hexString, hexString, hexString, hexString, initRandom, initRandom, makeClass, makeInt, makeLong, makeSessionKey, pastSpace, pickBits, pickBits, prettyPrint, prettyPrint, readBlock, readInt, trimArrayLength, trimArrayLength, trimLeadingZeroes, writeBytes, writeBytes, writeInt

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.logi.crypto.keys.Key

getFingerprint, getFingerprint, hashCode, matches, matchFingerprint, matchFingerprint

Methods inherited from interface org.logi.crypto.io.PrettyPrintable

prettyPrint, prettyPrint

Methods inherited from interface java.security.Key

getEncoded, getFormat

Constructor Detail

DESKey

public DESKey()

Create a new random DES key.

DESKey

public DESKey(byte[] key)

Create a new DES key with the key bits from key[0..7].

DESKey

public DESKey(long key)

Create a new DES key with the key bits from key.

Method Detail

parseCDS

public static DESKey parseCDS(java.lang.String[] param)
                       throws InvalidCDSException

Used by Crypto.fromString when parsing a CDS.

A valid CDS can be created by calling the toString() method.

Throws:

InvalidCDSException - if the CDS is malformed.

See Also:

Crypto.fromString(String)

plainBlockSize

public int plainBlockSize()

The block-size for the DES cipher is 8 bytes.

Specified by:

plainBlockSize in interface EncryptionKey

cipherBlockSize

public int cipherBlockSize()

The block-size for the DES cipher is 8 bytes.

Specified by:

cipherBlockSize in interface EncryptionKey

getSize

public int getSize()

The key-size for the DES cipher is 56 bits.

Specified by:

getSize in interface Key

getAlgorithm

public java.lang.String getAlgorithm()

The name of the algorithm is "DES".

Specified by:

getAlgorithm in interface Key

equals

public boolean equals(java.lang.Object o)

Return true iff the two keys are equivalent.

Overrides:

equals in class java.lang.Object

getKey

public byte[] getKey()

Return the key-bits for this key as an array of 8 bytes.

toString

public java.lang.String toString()

Return a CDS for this key.

Overrides:

toString in class java.lang.Object

See Also:

Crypto.fromString(java.io.Reader)

encrypt

public void encrypt(byte[] source,
                    int i,
                    byte[] dest,
                    int j)

Encrypt one block of data. The plaintext is taken from source[i..i+7] and ciphertext is written to dest[j..j+7]

Specified by:

encrypt in interface EncryptionKey

decrypt

public void decrypt(byte[] source,
                    int i,
                    byte[] dest,
                    int j)

Decrypt one block of data. The encrypted data is taken from dest[i..i+7] and plaintext is written to source[j..j+7].

Specified by:

decrypt in interface DecryptionKey

matches

public boolean matches(Key key)

Returns true if this and key are the same symmetric key.

Symmetric keys simply call equals(key).

getFingerprint

public final Fingerprint getFingerprint()

Return the key's fingerprint using the default hash function.

Specified by:

getFingerprint in interface Key

getFingerprint

public final Fingerprint getFingerprint(java.lang.String algorithm)
                                 throws InvalidCDSException

Return the key's fingerprint using the specified hash function.

Specified by:

getFingerprint in interface Key

Throws:

InvalidCDSException - if the specified hash function is not available.

matchFingerprint

public Fingerprint matchFingerprint()

Returns the default fingerprint of the matching key in the key-pair.

Specified by:

matchFingerprint in interface Key

matchFingerprint

public Fingerprint matchFingerprint(java.lang.String algorithm)
                             throws InvalidCDSException

Returns the default fingerprint of the matching key in the key-pair.

Specified by:

matchFingerprint in interface Key

Throws:

InvalidCDSException - if the specified hash function is not available.

hashCode

public final int hashCode()

Return a hash-code based on the keys SHA1 fingerprint.

Specified by:

hashCode in interface Key

Overrides:

hashCode in class java.lang.Object

getEncoded

public byte[] getEncoded()

Return encoded version.

Specified by:

getEncoded in interface java.security.Key

getFormat

public java.lang.String getFormat()

Returns the name of the key-encoding format.

Specified by:

getFormat in interface java.security.Key