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comparison src/com/trilead/ssh2/crypto/dh/DhGroupExchange.java @ 0:0ce5cc452d02

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initial version
author Carl Byington <carl@five-ten-sg.com>
date Thu, 22 May 2014 10:41:19 -0700
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-1:000000000000 0:0ce5cc452d02
1
2 package com.trilead.ssh2.crypto.dh;
3
4 import java.math.BigInteger;
5 import java.security.SecureRandom;
6
7 import com.trilead.ssh2.DHGexParameters;
8 import com.trilead.ssh2.crypto.digest.HashForSSH2Types;
9
10
11 /**
12 * DhGroupExchange.
13 *
14 * @author Christian Plattner, plattner@trilead.com
15 * @version $Id: DhGroupExchange.java,v 1.1 2007/10/15 12:49:57 cplattne Exp $
16 */
17 public class DhGroupExchange {
18 /* Given by the standard */
19
20 private BigInteger p;
21 private BigInteger g;
22
23 /* Client public and private */
24
25 private BigInteger e;
26 private BigInteger x;
27
28 /* Server public */
29
30 private BigInteger f;
31
32 /* Shared secret */
33
34 private BigInteger k;
35
36 public DhGroupExchange(BigInteger p, BigInteger g) {
37 this.p = p;
38 this.g = g;
39 }
40
41 public void init(SecureRandom rnd) {
42 k = null;
43 x = new BigInteger(p.bitLength() - 1, rnd);
44 e = g.modPow(x, p);
45 }
46
47 /**
48 * @return Returns the e.
49 */
50 public BigInteger getE() {
51 if (e == null)
52 throw new IllegalStateException("Not initialized!");
53
54 return e;
55 }
56
57 /**
58 * @return Returns the shared secret k.
59 */
60 public BigInteger getK() {
61 if (k == null)
62 throw new IllegalStateException("Shared secret not yet known, need f first!");
63
64 return k;
65 }
66
67 /**
68 * Sets f and calculates the shared secret.
69 */
70 public void setF(BigInteger f) {
71 if (e == null)
72 throw new IllegalStateException("Not initialized!");
73
74 BigInteger zero = BigInteger.valueOf(0);
75
76 if (zero.compareTo(f) >= 0 || p.compareTo(f) <= 0)
77 throw new IllegalArgumentException("Invalid f specified!");
78
79 this.f = f;
80 this.k = f.modPow(x, p);
81 }
82
83 public byte[] calculateH(String hashAlgo, byte[] clientversion, byte[] serverversion,
84 byte[] clientKexPayload, byte[] serverKexPayload, byte[] hostKey, DHGexParameters para) {
85 HashForSSH2Types hash = new HashForSSH2Types(hashAlgo);
86 hash.updateByteString(clientversion);
87 hash.updateByteString(serverversion);
88 hash.updateByteString(clientKexPayload);
89 hash.updateByteString(serverKexPayload);
90 hash.updateByteString(hostKey);
91
92 if (para.getMin_group_len() > 0)
93 hash.updateUINT32(para.getMin_group_len());
94
95 hash.updateUINT32(para.getPref_group_len());
96
97 if (para.getMax_group_len() > 0)
98 hash.updateUINT32(para.getMax_group_len());
99
100 hash.updateBigInt(p);
101 hash.updateBigInt(g);
102 hash.updateBigInt(e);
103 hash.updateBigInt(f);
104 hash.updateBigInt(k);
105 return hash.getDigest();
106 }
107 }