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package javax.crypto.spec;
import java.security.InvalidKeyException;
import java.security.spec.KeySpec;
/**
* This class specifies a DES key.
*/
public class DESKeySpec
implements KeySpec
{
public static final int DES_KEY_LEN = 8;
private byte[] keyBytes = new byte[DES_KEY_LEN];
/**
* Uses 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.
* @exception InvalidKeyException - if the given key material is shorter than 8 bytes.
*/
public DESKeySpec(
byte[] key)
throws InvalidKeyException
{
if (key.length < DES_KEY_LEN)
{
throw new InvalidKeyException("DES key material too short in construction");
}
System.arraycopy(key, 0, keyBytes, 0, keyBytes.length);
}
/**
* Uses 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.
* @param offset the offset in <code>key</code>, where the DES key material starts.
* @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("DES key material too short in construction");
}
System.arraycopy(key, offset, keyBytes, 0, keyBytes.length);
}
/**
* Returns the DES key material.
*
* @return the DES key material.
*/
public byte[] getKey()
{
byte[] tmp = new byte[DES_KEY_LEN];
System.arraycopy(keyBytes, 0, tmp, 0, tmp.length);
return tmp;
}
/**
* 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.
* @returns true if the given DES key material is parity-adjusted, false otherwise.
* @exception InvalidKeyException if the given key material, starting at <code>offset</code>
* inclusive, is shorter than 8 bytes.
*/
public static boolean isParityAdjusted(
byte[] key,
int offset)
throws InvalidKeyException
{
if ((key.length - offset) < DES_KEY_LEN)
{
throw new InvalidKeyException("key material too short in DESKeySpec.isParityAdjusted");
}
for (int i = 0; i < DES_KEY_LEN; i++)
{
byte keyByte = key[i + offset];
int count = 0;
keyByte = (byte)((keyByte & 0xff) >> 1);
while (keyByte != 0)
{
/*
* we increment for every "on" bit
*/
if ((keyByte & 0x01) != 0)
{
count++;
}
keyByte = (byte)((keyByte & 0xff) >> 1);
}
if ((count & 1) == 1)
{
if ((key[i + offset] & 1) == 1)
{
return false;
}
}
else if ((key[i + offset] & 1) != 1)
{
return false;
}
}
return true;
}
/*
* Table of weak and semi-weak keys taken from Schneier pp281
*/
static private final int N_DES_WEAK_KEYS = 16;
static private byte[] DES_weak_keys =
{
/* weak keys */
(byte)0x01,(byte)0x01,(byte)0x01,(byte)0x01, (byte)0x01,(byte)0x01,(byte)0x01,(byte)0x01,
(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)0xfe,(byte)0xfe,(byte)0xfe,(byte)0xfe, (byte)0xfe,(byte)0xfe,(byte)0xfe,(byte)0xfe,
/* semi-weak keys */
(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
};
/**
* 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, starting at <code>offset</code>
* inclusive, is shorter than 8 bytes.
*/
public static boolean isWeak(
byte[] key,
int offset)
throws InvalidKeyException
{
if (key.length - offset < DES_KEY_LEN)
{
throw new InvalidKeyException("key material too short in DESKeySpec.isWeak");
}
nextkey: for (int i = 0; i < N_DES_WEAK_KEYS; i++)
{
for (int j = 0; j < DES_KEY_LEN; j++)
{
if (key[j + offset] != DES_weak_keys[i * DES_KEY_LEN + j])
{
continue nextkey;
}
}
return true;
}
return false;
}
}
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