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comparison app/src/main/java/ch/ethz/ssh2/crypto/dh/DhGroupExchange.java @ 438:d29cce60f393

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migrate from Eclipse to Android Studio
author Carl Byington <carl@five-ten-sg.com>
date Thu, 03 Dec 2015 11:23:55 -0800
parents src/ch/ethz/ssh2/crypto/dh/DhGroupExchange.java@1d400fd78e4a
children
comparison
equal deleted inserted replaced
437:208b31032318 438:d29cce60f393
1
2 package ch.ethz.ssh2.crypto.dh;
3
4 import java.math.BigInteger;
5 import java.security.SecureRandom;
6 import java.io.IOException;
7
8 import ch.ethz.ssh2.DHGexParameters;
9 import ch.ethz.ssh2.crypto.digest.HashForSSH2Types;
10
11
12 /**
13 * DhGroupExchange.
14 *
15 * @author Christian Plattner, plattner@trilead.com
16 * @version $Id: DhGroupExchange.java,v 1.1 2007/10/15 12:49:57 cplattne Exp $
17 */
18 public class DhGroupExchange {
19 /* Given by the standard */
20
21 private BigInteger p;
22 private BigInteger g;
23
24 /* Client public and private */
25
26 private BigInteger e;
27 private BigInteger x;
28
29 /* Server public */
30
31 private BigInteger f;
32
33 /* Shared secret */
34
35 private BigInteger k;
36
37 public DhGroupExchange(BigInteger p, BigInteger g) {
38 this.p = p;
39 this.g = g;
40 }
41
42 public void init(SecureRandom rnd) {
43 k = null;
44 x = new BigInteger(p.bitLength() - 1, rnd);
45 e = g.modPow(x, p);
46 }
47
48 /**
49 * @return Returns the e.
50 */
51 public BigInteger getE() {
52 if (e == null)
53 throw new IllegalStateException("Not initialized!");
54
55 return e;
56 }
57
58 /**
59 * @return Returns the shared secret k.
60 */
61 public BigInteger getK() {
62 if (k == null)
63 throw new IllegalStateException("Shared secret not yet known, need f first!");
64
65 return k;
66 }
67
68 /**
69 * Sets f and calculates the shared secret.
70 */
71 public void setF(BigInteger f) {
72 if (e == null)
73 throw new IllegalStateException("Not initialized!");
74
75 BigInteger zero = BigInteger.valueOf(0);
76
77 if (zero.compareTo(f) >= 0 || p.compareTo(f) <= 0)
78 throw new IllegalArgumentException("Invalid f specified!");
79
80 this.f = f;
81 this.k = f.modPow(x, p);
82 }
83
84 public byte[] calculateH(String hashAlgo, byte[] clientversion, byte[] serverversion,
85 byte[] clientKexPayload, byte[] serverKexPayload, byte[] hostKey, DHGexParameters para) throws IOException {
86 HashForSSH2Types hash = new HashForSSH2Types(hashAlgo);
87 hash.updateByteString(clientversion);
88 hash.updateByteString(serverversion);
89 hash.updateByteString(clientKexPayload);
90 hash.updateByteString(serverKexPayload);
91 hash.updateByteString(hostKey);
92
93 if (para.getMin_group_len() > 0)
94 hash.updateUINT32(para.getMin_group_len());
95
96 hash.updateUINT32(para.getPref_group_len());
97
98 if (para.getMax_group_len() > 0)
99 hash.updateUINT32(para.getMax_group_len());
100
101 hash.updateBigInt(p);
102 hash.updateBigInt(g);
103 hash.updateBigInt(e);
104 hash.updateBigInt(f);
105 hash.updateBigInt(k);
106 return hash.getDigest();
107 }
108 }