1 /**
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19
20 package org.apache.ws.security.conversation.dkalgo;
21
22 /**
23 *
24 <pre>
25 P_SHA-1 DEFINITION
26 ==================
27 <b>P_SHA-1(secret, seed)</b> =
28 HMAC_SHA-1(secret, A(1) + seed) +
29 HMAC_SHA-1(secret, A(2) + seed) +
30 HMAC_SHA-1(secret, A(3) + seed) + ...
31 <i>Where + indicates concatenation.</i>
32 <br>
33 A() is defined as:
34 A(0) = seed
35 A(i) = HMAC_SHA-1(secret, A(i-1))
36 <br>
37 <i>Source : RFC 2246 - The TLS Protocol Version 1.0
38 Section 5. HMAC and the pseudorandom function</i>
39 </pre>
40 *
41 * @author Ruchith Fernando
42 */
43
44 import javax.crypto.Mac;
45 import javax.crypto.spec.SecretKeySpec;
46
47 import org.apache.ws.security.conversation.ConversationException;
48
49 public class P_SHA1 implements DerivationAlgorithm {
50
51 public byte[] createKey(byte[] secret, byte[] seed, int offset,
52 long length) throws ConversationException {
53 try {
54 Mac mac = Mac.getInstance("HmacSHA1");
55
56 byte[] tempBytes = P_hash(secret, seed, mac, (offset + (int) length));
57
58 byte[] key = new byte[(int) length];
59
60 for (int i = 0; i < key.length; i++) {
61 key[i] = tempBytes[i + offset];
62 }
63
64 return key;
65 } catch (Exception ex) {
66 throw new ConversationException("errorInKeyDerivation", null, ex);
67 }
68 }
69
70 /**
71 * From WSUsernameToken :-)
72 *
73 * @param secret
74 * @param seed
75 * @param mac
76 * @param required
77 * @return
78 * @throws java.lang.Exception
79 */
80 private static byte[] P_hash(byte[] secret, byte[] seed, Mac mac, int required) throws Exception {
81 byte[] out = new byte[required];
82 int offset = 0, tocpy;
83 byte[] a, tmp;
84 a = seed;
85 while (required > 0) {
86 SecretKeySpec key = new SecretKeySpec(secret, "HMACSHA1");
87 mac.init(key);
88 mac.update(a);
89 a = mac.doFinal();
90 mac.reset();
91 mac.init(key);
92 mac.update(a);
93 mac.update(seed);
94 tmp = mac.doFinal();
95 tocpy = min(required, tmp.length);
96 System.arraycopy(tmp, 0, out, offset, tocpy);
97 offset += tocpy;
98 required -= tocpy;
99 }
100 return out;
101 }
102
103 private static int min(int a, int b) {
104 return (a > b) ? b : a;
105 }
106
107 }