/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*
*/
package org.apache.directory.server.kerberos.shared.crypto.encryption;
import java.security.GeneralSecurityException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.spec.AlgorithmParameterSpec;
import java.util.Arrays;
import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import org.apache.directory.server.kerberos.shared.exceptions.ErrorType;
import org.apache.directory.server.kerberos.shared.exceptions.KerberosException;
import org.apache.directory.server.kerberos.shared.messages.value.EncryptedData;
import org.apache.directory.server.kerberos.shared.messages.value.EncryptionKey;
import org.apache.directory.shared.ldap.constants.LdapSecurityConstants;
/**
* @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
* @version $Rev: 602574 $, $Date: 2007-12-09 00:10:21 +0100 (Dim, 09 déc 2007) $
*/
class DesCbcMd5Encryption extends EncryptionEngine
{
private static final byte[] iv = new byte[]
{ ( byte ) 0x00, ( byte ) 0x00, ( byte ) 0x00, ( byte ) 0x00, ( byte ) 0x00, ( byte ) 0x00, ( byte ) 0x00,
( byte ) 0x00 };
public EncryptionType getEncryptionType()
{
return EncryptionType.DES_CBC_MD5;
}
public int getConfounderLength()
{
return 8;
}
public int getChecksumLength()
{
return 16;
}
public byte[] calculateIntegrity( byte[] data, byte[] key, KeyUsage usage )
{
try
{
MessageDigest digester = MessageDigest.getInstance( LdapSecurityConstants.HASH_METHOD_MD5.getName() );
return digester.digest( data );
}
catch ( NoSuchAlgorithmException nsae )
{
return null;
}
}
public byte[] getDecryptedData( EncryptionKey key, EncryptedData data, KeyUsage usage ) throws KerberosException
{
// decrypt the data
byte[] decryptedData = decrypt( data.getCipher(), key.getKeyValue() );
// extract the old checksum
byte[] oldChecksum = new byte[getChecksumLength()];
System.arraycopy( decryptedData, getConfounderLength(), oldChecksum, 0, oldChecksum.length );
// zero out the old checksum in the cipher text
for ( int i = getConfounderLength(); i < getConfounderLength() + getChecksumLength(); i++ )
{
decryptedData[i] = 0;
}
// calculate a new checksum
byte[] newChecksum = calculateIntegrity( decryptedData, key.getKeyValue(), usage );
// compare checksums
if ( !Arrays.equals( oldChecksum, newChecksum ) )
{
throw new KerberosException( ErrorType.KRB_AP_ERR_BAD_INTEGRITY );
}
// remove leading confounder and checksum
return removeLeadingBytes( decryptedData, getConfounderLength(), getChecksumLength() );
}
public EncryptedData getEncryptedData( EncryptionKey key, byte[] plainText, KeyUsage usage )
{
// build the ciphertext structure
byte[] conFounder = getRandomBytes( getConfounderLength() );
byte[] zeroedChecksum = new byte[getChecksumLength()];
byte[] dataBytes = concatenateBytes( conFounder, concatenateBytes( zeroedChecksum, plainText ) );
byte[] paddedDataBytes = padString( dataBytes );
byte[] checksumBytes = calculateIntegrity( paddedDataBytes, null, usage );
// lay the checksum into the ciphertext
for ( int i = getConfounderLength(); i < getConfounderLength() + getChecksumLength(); i++ )
{
paddedDataBytes[i] = checksumBytes[i - getConfounderLength()];
}
byte[] encryptedData = encrypt( paddedDataBytes, key.getKeyValue() );
return new EncryptedData( getEncryptionType(), key.getKeyVersion(), encryptedData );
}
public byte[] encrypt( byte[] plainText, byte[] keyBytes )
{
return processCipher( true, plainText, keyBytes );
}
public byte[] decrypt( byte[] cipherText, byte[] keyBytes )
{
return processCipher( false, cipherText, keyBytes );
}
private byte[] processCipher( boolean isEncrypt, byte[] data, byte[] keyBytes )
{
try
{
Cipher cipher = Cipher.getInstance( "DES/CBC/NoPadding" );
SecretKey key = new SecretKeySpec( keyBytes, "DES" );
AlgorithmParameterSpec paramSpec = new IvParameterSpec( iv );
if ( isEncrypt )
{
cipher.init( Cipher.ENCRYPT_MODE, key, paramSpec );
}
else
{
cipher.init( Cipher.DECRYPT_MODE, key, paramSpec );
}
return cipher.doFinal( data );
}
catch ( GeneralSecurityException nsae )
{
nsae.printStackTrace();
return null;
}
}
}