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package javax.crypto.spec;
import java.security.InvalidKeyException;
import java.security.spec.KeySpec;
/**
* This class specifies a DES-EDE ("triple-DES") key.
*/
public class DESedeKeySpec
implements KeySpec
{
public static final int DES_EDE_KEY_LEN = 24;
private byte[] keyBytes = new byte[DES_EDE_KEY_LEN];
/**
* Uses the first 24 bytes in <code>key</code> as the DES-EDE key.
* <p>
* The bytes that constitute the DES-EDE key are those between
* <code>key[0]</code> and <code>key[23]</code> inclusive
*
* @param key the buffer with the DES-EDE key material.
* @exception InvalidKeyException if the given key material is shorter
* than 24 bytes.
*/
public DESedeKeySpec(
byte[] key)
throws InvalidKeyException
{
if (key.length < DES_EDE_KEY_LEN)
{
throw new InvalidKeyException("DESede key material too short in construction");
}
System.arraycopy(key, 0, keyBytes, 0, keyBytes.length);
}
/**
* Uses the first 24 bytes in <code>key</code>, beginning at
* <code>offset</code> inclusive, as the DES-EDE key.
* <p>
* The bytes that constitute the DES-EDE key are those between
* <code>key[offset]</code> and <code>key[offset+23]</code> inclusive.
* @param key the buffer with the DES-EDE key material.
* @param offset the offset in <code>key</code>, where the DES-EDE key
* material starts.
* @exception InvalidKeyException if the given key material, starting at
* <code>offset</code> inclusive, is shorter than 24 bytes
*/
public DESedeKeySpec(
byte[] key,
int offset)
throws InvalidKeyException
{
if ((key.length - offset) < DES_EDE_KEY_LEN)
{
throw new InvalidKeyException("DESede key material too short in construction");
}
System.arraycopy(key, 0, keyBytes, 0, keyBytes.length);
}
/**
* Returns the DES-EDE key.
*
* @return the DES-EDE key
*/
public byte[] getKey()
{
byte[] tmp = new byte[DES_EDE_KEY_LEN];
System.arraycopy(keyBytes, 0, tmp, 0, tmp.length);
return tmp;
}
/**
* Checks if the given DES-EDE key, starting at <code>offset</code>
* inclusive, is parity-adjusted.
*
* @return true if the given DES-EDE key is parity-adjusted, false
* otherwise
* @exception InvalidKeyException if the given key material, starting at
* <code>offset</code> inclusive, is shorter than 24 bytes
*/
public static boolean isParityAdjusted(
byte[] key,
int offset)
throws InvalidKeyException
{
if ((key.length - offset) < DES_EDE_KEY_LEN)
{
throw new InvalidKeyException("key material too short in DESedeKeySpec.isParityAdjusted");
}
return (DESKeySpec.isParityAdjusted(key, offset)
&& DESKeySpec.isParityAdjusted(key, offset + 8)
&& DESKeySpec.isParityAdjusted(key, offset + 16));
}
}
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