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package javax.crypto.spec;
import java.security.InvalidKeyException;
This class specifies a DES key.
Author: Jan Luehe Since: 1.4
/**
* This class specifies a DES key.
*
* @author Jan Luehe
*
* @since 1.4
*/
public class DESKeySpec implements java.security.spec.KeySpec {
The constant which defines the length of a DES key in bytes.
/**
* The constant which defines the length of a DES key in bytes.
*/
public static final int DES_KEY_LEN = 8;
private byte[] key;
/*
* Weak/semi-weak keys copied from FIPS 74.
*
* "...The first 6 keys have duals different than themselves, hence
* each is both a key and a dual giving 12 keys with duals. The last
* four keys equal their duals, and are called self-dual keys..."
*
* 1. E001E001F101F101 01E001E001F101F1
* 2. FE1FFE1FFEOEFEOE 1FFE1FFEOEFEOEFE
* 3. E01FE01FF10EF10E 1FE01FEOOEF10EF1
* 4. 01FE01FE01FE01FE FE01FE01FE01FE01
* 5. 011F011F010E010E 1F011F010E010E01
* 6. E0FEE0FEF1FEF1FE FEE0FEE0FEF1FEF1
* 7. 0101010101010101 0101010101010101
* 8. FEFEFEFEFEFEFEFE FEFEFEFEFEFEFEFE
* 9. E0E0E0E0F1F1F1F1 E0E0E0E0F1F1F1F1
* 10. 1F1F1F1F0E0E0E0E 1F1F1F1F0E0E0E0E
*/
private static final byte[][] WEAK_KEYS = {
{ (byte)0x01, (byte)0x01, (byte)0x01, (byte)0x01, (byte)0x01,
(byte)0x01, (byte)0x01, (byte)0x01 },
{ (byte)0xFE, (byte)0xFE, (byte)0xFE, (byte)0xFE, (byte)0xFE,
(byte)0xFE, (byte)0xFE, (byte)0xFE },
{ (byte)0x1F, (byte)0x1F, (byte)0x1F, (byte)0x1F, (byte)0x0E,
(byte)0x0E, (byte)0x0E, (byte)0x0E },
{ (byte)0xE0, (byte)0xE0, (byte)0xE0, (byte)0xE0, (byte)0xF1,
(byte)0xF1, (byte)0xF1, (byte)0xF1 },
{ (byte)0x01, (byte)0xFE, (byte)0x01, (byte)0xFE, (byte)0x01,
(byte)0xFE, (byte)0x01, (byte)0xFE },
{ (byte)0x1F, (byte)0xE0, (byte)0x1F, (byte)0xE0, (byte)0x0E,
(byte)0xF1, (byte)0x0E, (byte)0xF1 },
{ (byte)0x01, (byte)0xE0, (byte)0x01, (byte)0xE0, (byte)0x01,
(byte)0xF1, (byte)0x01, (byte)0xF1 },
{ (byte)0x1F, (byte)0xFE, (byte)0x1F, (byte)0xFE, (byte)0x0E,
(byte)0xFE, (byte)0x0E, (byte)0xFE },
{ (byte)0x01, (byte)0x1F, (byte)0x01, (byte)0x1F, (byte)0x01,
(byte)0x0E, (byte)0x01, (byte)0x0E },
{ (byte)0xE0, (byte)0xFE, (byte)0xE0, (byte)0xFE, (byte)0xF1,
(byte)0xFE, (byte)0xF1, (byte)0xFE },
{ (byte)0xFE, (byte)0x01, (byte)0xFE, (byte)0x01, (byte)0xFE,
(byte)0x01, (byte)0xFE, (byte)0x01 },
{ (byte)0xE0, (byte)0x1F, (byte)0xE0, (byte)0x1F, (byte)0xF1,
(byte)0x0E, (byte)0xF1, (byte)0x0E },
{ (byte)0xE0, (byte)0x01, (byte)0xE0, (byte)0x01, (byte)0xF1,
(byte)0x01, (byte)0xF1, (byte)0x01 },
{ (byte)0xFE, (byte)0x1F, (byte)0xFE, (byte)0x1F, (byte)0xFE,
(byte)0x0E, (byte)0xFE, (byte)0x0E },
{ (byte)0x1F, (byte)0x01, (byte)0x1F, (byte)0x01, (byte)0x0E,
(byte)0x01, (byte)0x0E, (byte)0x01 },
{ (byte)0xFE, (byte)0xE0, (byte)0xFE, (byte)0xE0, (byte)0xFE,
(byte)0xF1, (byte)0xFE, (byte)0xF1 }
};
Creates a DESKeySpec object using the first 8 bytes in
key as the key material for the DES key.
The bytes that constitute the DES key are those between
key[0] and key[7] inclusive.
Params: - key – the buffer with the DES key material. The first 8 bytes
of the buffer are copied to protect against subsequent modification.
Throws: - NullPointerException – if the given key material is
null - InvalidKeyException – if the given key material is shorter
than 8 bytes.
/**
* Creates a DESKeySpec object using the first 8 bytes in
* <code>key</code> as the key material for the DES key.
*
* <p> The bytes that constitute the DES key are those between
* <code>key[0]</code> and <code>key[7]</code> inclusive.
*
* @param key the buffer with the DES key material. The first 8 bytes
* of the buffer are copied to protect against subsequent modification.
*
* @exception NullPointerException if the given key material is
* <code>null</code>
* @exception InvalidKeyException if the given key material is shorter
* than 8 bytes.
*/
public DESKeySpec(byte[] key) throws InvalidKeyException {
this(key, 0);
}
Creates a DESKeySpec object using the first 8 bytes in
key, beginning at offset inclusive,
as the key material for the DES key.
The bytes that constitute the DES key are those between
key[offset] and key[offset+7] inclusive.
Params: - key – the buffer with the DES key material. The first 8 bytes
of the buffer beginning at
offset inclusive are copied
to protect against subsequent modification. - offset – the offset in
key, where the DES key
material starts.
Throws: - NullPointerException – if the given key material is
null - InvalidKeyException – if the given key material, starting at
offset inclusive, is shorter than 8 bytes.
/**
* Creates a DESKeySpec object using the first 8 bytes in
* <code>key</code>, beginning at <code>offset</code> inclusive,
* as the key material for the DES key.
*
* <p> The bytes that constitute the DES key are those between
* <code>key[offset]</code> and <code>key[offset+7]</code> inclusive.
*
* @param key the buffer with the DES key material. The first 8 bytes
* of the buffer beginning at <code>offset</code> inclusive are copied
* to protect against subsequent modification.
* @param offset the offset in <code>key</code>, where the DES key
* material starts.
*
* @exception NullPointerException if the given key material is
* <code>null</code>
* @exception InvalidKeyException if the given key material, starting at
* <code>offset</code> inclusive, is shorter than 8 bytes.
*/
public DESKeySpec(byte[] key, int offset) throws InvalidKeyException {
if (key.length - offset < DES_KEY_LEN) {
throw new InvalidKeyException("Wrong key size");
}
this.key = new byte[DES_KEY_LEN];
System.arraycopy(key, offset, this.key, 0, DES_KEY_LEN);
}
Returns the DES key material.
Returns: the DES key material. Returns a new array
each time this method is called.
/**
* Returns the DES key material.
*
* @return the DES key material. Returns a new array
* each time this method is called.
*/
public byte[] getKey() {
return this.key.clone();
}
Checks if the given DES key material, starting at offset
inclusive, is parity-adjusted.
Params: - key – the buffer with the DES key material.
- offset – the offset in
key, where the DES key
material starts.
Throws: - InvalidKeyException – if the given key material is
null, or starting at offset inclusive, is
shorter than 8 bytes.
Returns: true if the given DES key material is parity-adjusted, false
otherwise.
/**
* Checks if the given DES key material, starting at <code>offset</code>
* inclusive, is parity-adjusted.
*
* @param key the buffer with the DES key material.
* @param offset the offset in <code>key</code>, where the DES key
* material starts.
*
* @return true if the given DES key material is parity-adjusted, false
* otherwise.
*
* @exception InvalidKeyException if the given key material is
* <code>null</code>, or starting at <code>offset</code> inclusive, is
* shorter than 8 bytes.
*/
public static boolean isParityAdjusted(byte[] key, int offset)
throws InvalidKeyException {
if (key == null) {
throw new InvalidKeyException("null key");
}
if (key.length - offset < DES_KEY_LEN) {
throw new InvalidKeyException("Wrong key size");
}
for (int i = 0; i < DES_KEY_LEN; i++) {
int k = Integer.bitCount(key[offset++] & 0xff);
if ((k & 1) == 0) {
return false;
}
}
return true;
}
Checks if the given DES key material is weak or semi-weak.
Params: - key – the buffer with the DES key material.
- offset – the offset in
key, where the DES key
material starts.
Throws: - InvalidKeyException – if the given key material is
null, or starting at offset inclusive, is
shorter than 8 bytes.
Returns: true if the given DES key material is weak or semi-weak, false
otherwise.
/**
* Checks if the given DES key material is weak or semi-weak.
*
* @param key the buffer with the DES key material.
* @param offset the offset in <code>key</code>, where the DES key
* material starts.
*
* @return true if the given DES key material is weak or semi-weak, false
* otherwise.
*
* @exception InvalidKeyException if the given key material is
* <code>null</code>, or starting at <code>offset</code> inclusive, is
* shorter than 8 bytes.
*/
public static boolean isWeak(byte[] key, int offset)
throws InvalidKeyException {
if (key == null) {
throw new InvalidKeyException("null key");
}
if (key.length - offset < DES_KEY_LEN) {
throw new InvalidKeyException("Wrong key size");
}
for (int i = 0; i < WEAK_KEYS.length; i++) {
boolean found = true;
for (int j = 0; j < DES_KEY_LEN && found == true; j++) {
if (WEAK_KEYS[i][j] != key[j+offset]) {
found = false;
}
}
if (found == true) {
return found;
}
}
return false;
}
}