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comparison src/ch/ethz/ssh2/crypto/dh/DhGroupExchange.java @ 273:91a31873c42a ganymed

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start conversion from trilead to ganymed
author Carl Byington <carl@five-ten-sg.com>
date Fri, 18 Jul 2014 11:21:46 -0700
parents
children 071eccdff8ea
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272:ce2f4e397703 273:91a31873c42a
1 /*
2 * Copyright (c) 2006-2011 Christian Plattner. All rights reserved.
3 * Please refer to the LICENSE.txt for licensing details.
4 */
5 package ch.ethz.ssh2.crypto.dh;
6
7 import java.io.IOException;
8 import java.math.BigInteger;
9 import java.security.SecureRandom;
10
11 import ch.ethz.ssh2.DHGexParameters;
12 import ch.ethz.ssh2.crypto.digest.HashForSSH2Types;
13
14 /**
15 * DhGroupExchange.
16 *
17 * @author Christian Plattner
18 * @version 2.50, 03/15/10
19 */
20 public class DhGroupExchange {
21 /* Given by the standard */
22
23 private BigInteger p;
24 private BigInteger g;
25
26 /* Client public and private */
27
28 private BigInteger e;
29 private BigInteger x;
30
31 /* Server public */
32
33 private BigInteger f;
34
35 /* Shared secret */
36
37 private BigInteger k;
38
39 public DhGroupExchange(BigInteger p, BigInteger g) {
40 this.p = p;
41 this.g = g;
42 }
43
44 public void init(SecureRandom rnd) {
45 k = null;
46
47 x = new BigInteger(p.bitLength() - 1, rnd);
48 e = g.modPow(x, p);
49 }
50
51 /**
52 * @return Returns the e.
53 */
54 public BigInteger getE() {
55 if(e == null) {
56 throw new IllegalStateException("Not initialized!");
57 }
58
59 return e;
60 }
61
62 /**
63 * @return Returns the shared secret k.
64 */
65 public BigInteger getK() {
66 if(k == null) {
67 throw new IllegalStateException("Shared secret not yet known, need f first!");
68 }
69
70 return k;
71 }
72
73 /**
74 * Sets f and calculates the shared secret.
75 */
76 public void setF(BigInteger f) {
77 if(e == null) {
78 throw new IllegalStateException("Not initialized!");
79 }
80
81 BigInteger zero = BigInteger.valueOf(0);
82
83 if(zero.compareTo(f) >= 0 || p.compareTo(f) <= 0) {
84 throw new IllegalArgumentException("Invalid f specified!");
85 }
86
87 this.f = f;
88 this.k = f.modPow(x, p);
89 }
90
91 public byte[] calculateH(byte[] clientversion, byte[] serverversion, byte[] clientKexPayload,
92 byte[] serverKexPayload, byte[] hostKey, DHGexParameters para) throws IOException {
93 HashForSSH2Types hash = new HashForSSH2Types("SHA1");
94
95 hash.updateByteString(clientversion);
96 hash.updateByteString(serverversion);
97 hash.updateByteString(clientKexPayload);
98 hash.updateByteString(serverKexPayload);
99 hash.updateByteString(hostKey);
100 if(para.getMin_group_len() > 0) {
101 hash.updateUINT32(para.getMin_group_len());
102 }
103 hash.updateUINT32(para.getPref_group_len());
104 if(para.getMax_group_len() > 0) {
105 hash.updateUINT32(para.getMax_group_len());
106 }
107 hash.updateBigInt(p);
108 hash.updateBigInt(g);
109 hash.updateBigInt(e);
110 hash.updateBigInt(f);
111 hash.updateBigInt(k);
112
113 return hash.getDigest();
114 }
115 }