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 10:21:20 +0200 (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 }