001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements. See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership. The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License. You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied. See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 *
019 */
020 package org.apache.directory.server.kerberos.sam;
021
022
023 import java.io.IOException;
024
025 import javax.security.auth.kerberos.KerberosKey;
026
027 import org.apache.directory.server.kerberos.shared.crypto.encryption.CipherTextHandler;
028 import org.apache.directory.server.kerberos.shared.crypto.encryption.EncryptionType;
029 import org.apache.directory.server.kerberos.shared.crypto.encryption.KeyUsage;
030 import org.apache.directory.server.kerberos.shared.exceptions.KerberosException;
031 import org.apache.directory.server.kerberos.shared.io.decoder.EncryptedDataDecoder;
032 import org.apache.directory.server.kerberos.shared.messages.value.EncryptedData;
033 import org.apache.directory.server.kerberos.shared.messages.value.EncryptedTimeStamp;
034 import org.apache.directory.server.kerberos.shared.messages.value.EncryptionKey;
035 import org.apache.directory.server.kerberos.shared.messages.value.KerberosTime;
036
037
038 /**
039 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
040 * @version $Rev: 563062 $, $Date: 2007-08-06 11:21:20 +0300 (Mon, 06 Aug 2007) $
041 */
042 public class TimestampChecker implements KeyIntegrityChecker
043 {
044 private static final long FIVE_MINUTES = 300000;
045 private static final CipherTextHandler cipherTextHandler = new CipherTextHandler();
046
047
048 public boolean checkKeyIntegrity( byte[] encryptedData, KerberosKey kerberosKey )
049 {
050 EncryptionType keyType = EncryptionType.getTypeByOrdinal( kerberosKey.getKeyType() );
051 EncryptionKey key = new EncryptionKey( keyType, kerberosKey.getEncoded() );
052
053 try
054 {
055 /*
056 * Since the pre-auth value is of type PA-ENC-TIMESTAMP, it should be a valid
057 * ASN.1 PA-ENC-TS-ENC structure, so we can decode it into EncryptedData.
058 */
059 EncryptedData sadValue = EncryptedDataDecoder.decode( encryptedData );
060
061 /*
062 * Decrypt the EncryptedData structure to get the PA-ENC-TS-ENC. Decode the
063 * decrypted timestamp into our timestamp object.
064 */
065 EncryptedTimeStamp timestamp = ( EncryptedTimeStamp ) cipherTextHandler.unseal( EncryptedTimeStamp.class,
066 key, sadValue, KeyUsage.NUMBER1 );
067
068 /*
069 * Since we got here we must have a valid timestamp structure that we can
070 * validate to be within a five minute skew.
071 */
072 KerberosTime time = timestamp.getTimeStamp();
073
074 if ( time.isInClockSkew( FIVE_MINUTES ) )
075 {
076 return true;
077 }
078 }
079 catch ( IOException ioe )
080 {
081 return false;
082 }
083 catch ( KerberosException ke )
084 {
085 return false;
086 }
087 catch ( ClassCastException cce )
088 {
089 return false;
090 }
091
092 return false;
093 }
094 }