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comparison src/ch/ethz/ssh2/signature/DSASHA1Verify.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
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children d7e088fa2123
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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.signature;
6
7 import java.io.IOException;
8 import java.math.BigInteger;
9 import java.security.DigestException;
10 import java.security.SecureRandom;
11
12 import ch.ethz.ssh2.PacketFormatException;
13 import ch.ethz.ssh2.crypto.digest.SHA1;
14 import ch.ethz.ssh2.log.Logger;
15 import ch.ethz.ssh2.packets.TypesReader;
16 import ch.ethz.ssh2.packets.TypesWriter;
17
18 /**
19 * DSASHA1Verify.
20 *
21 * @author Christian Plattner
22 * @version $Id: DSASHA1Verify.java 154 2014-04-28 11:45:02Z dkocher@sudo.ch $
23 */
24 public class DSASHA1Verify {
25 private static final Logger log = Logger.getLogger(DSASHA1Verify.class);
26
27 public static DSAPublicKey decodeSSHDSAPublicKey(byte[] key) throws IOException {
28 TypesReader tr = new TypesReader(key);
29
30 String key_format = tr.readString();
31
32 if(!key_format.equals("ssh-dss")) {
33 throw new IllegalArgumentException("Not a ssh-dss public key");
34 }
35
36 BigInteger p = tr.readMPINT();
37 BigInteger q = tr.readMPINT();
38 BigInteger g = tr.readMPINT();
39 BigInteger y = tr.readMPINT();
40
41 if(tr.remain() != 0) {
42 throw new PacketFormatException("Padding in DSA public key");
43 }
44
45 return new DSAPublicKey(p, q, g, y);
46 }
47
48 public static byte[] encodeSSHDSAPublicKey(DSAPublicKey pk) throws IOException {
49 TypesWriter tw = new TypesWriter();
50
51 tw.writeString("ssh-dss");
52 tw.writeMPInt(pk.getP());
53 tw.writeMPInt(pk.getQ());
54 tw.writeMPInt(pk.getG());
55 tw.writeMPInt(pk.getY());
56
57 return tw.getBytes();
58 }
59
60 public static byte[] encodeSSHDSASignature(DSASignature ds) {
61 TypesWriter tw = new TypesWriter();
62
63 tw.writeString("ssh-dss");
64
65 byte[] r = ds.getR().toByteArray();
66 byte[] s = ds.getS().toByteArray();
67
68 byte[] a40 = new byte[40];
69
70 /* Patch (unsigned) r and s into the target array. */
71
72 int r_copylen = (r.length < 20) ? r.length : 20;
73 int s_copylen = (s.length < 20) ? s.length : 20;
74
75 System.arraycopy(r, r.length - r_copylen, a40, 20 - r_copylen, r_copylen);
76 System.arraycopy(s, s.length - s_copylen, a40, 40 - s_copylen, s_copylen);
77
78 tw.writeString(a40, 0, 40);
79
80 return tw.getBytes();
81 }
82
83 public static DSASignature decodeSSHDSASignature(byte[] sig) throws IOException {
84 byte[] rsArray;
85
86 if(sig.length == 40) {
87 rsArray = sig;
88 }
89 else {
90 TypesReader tr = new TypesReader(sig);
91
92 String sig_format = tr.readString();
93
94 if(sig_format.equals("ssh-dss") == false) {
95 throw new PacketFormatException("Peer sent wrong signature format");
96 }
97
98 rsArray = tr.readByteString();
99
100 if(rsArray.length != 40) {
101 throw new PacketFormatException("Peer sent corrupt signature");
102 }
103
104 if(tr.remain() != 0) {
105 throw new PacketFormatException("Padding in DSA signature!");
106 }
107 }
108
109 /* Remember, s and r are unsigned ints. */
110
111 byte[] tmp = new byte[20];
112
113 System.arraycopy(rsArray, 0, tmp, 0, 20);
114 BigInteger r = new BigInteger(1, tmp);
115
116 System.arraycopy(rsArray, 20, tmp, 0, 20);
117 BigInteger s = new BigInteger(1, tmp);
118
119 if(log.isDebugEnabled()) {
120 log.debug("decoded ssh-dss signature: first bytes r(" + ((rsArray[0]) & 0xff) + "), s("
121 + ((rsArray[20]) & 0xff) + ")");
122 }
123
124 return new DSASignature(r, s);
125 }
126
127 public static boolean verifySignature(byte[] message, DSASignature ds, DSAPublicKey dpk) throws IOException {
128 /* Inspired by Bouncycastle's DSASigner class */
129
130 SHA1 md = new SHA1();
131 md.update(message);
132 byte[] sha_message = new byte[md.getDigestLength()];
133 try {
134 md.digest(sha_message);
135 }
136 catch(DigestException e) {
137 throw new IOException(e);
138 }
139
140 BigInteger m = new BigInteger(1, sha_message);
141
142 BigInteger r = ds.getR();
143 BigInteger s = ds.getS();
144
145 BigInteger g = dpk.getG();
146 BigInteger p = dpk.getP();
147 BigInteger q = dpk.getQ();
148 BigInteger y = dpk.getY();
149
150 BigInteger zero = BigInteger.ZERO;
151
152 if(log.isDebugEnabled()) {
153 log.debug("ssh-dss signature: m: " + m.toString(16));
154 log.debug("ssh-dss signature: r: " + r.toString(16));
155 log.debug("ssh-dss signature: s: " + s.toString(16));
156 log.debug("ssh-dss signature: g: " + g.toString(16));
157 log.debug("ssh-dss signature: p: " + p.toString(16));
158 log.debug("ssh-dss signature: q: " + q.toString(16));
159 log.debug("ssh-dss signature: y: " + y.toString(16));
160 }
161
162 if(zero.compareTo(r) >= 0 || q.compareTo(r) <= 0) {
163 log.warning("ssh-dss signature: zero.compareTo(r) >= 0 || q.compareTo(r) <= 0");
164 return false;
165 }
166
167 if(zero.compareTo(s) >= 0 || q.compareTo(s) <= 0) {
168 log.warning("ssh-dss signature: zero.compareTo(s) >= 0 || q.compareTo(s) <= 0");
169 return false;
170 }
171
172 BigInteger w = s.modInverse(q);
173
174 BigInteger u1 = m.multiply(w).mod(q);
175 BigInteger u2 = r.multiply(w).mod(q);
176
177 u1 = g.modPow(u1, p);
178 u2 = y.modPow(u2, p);
179
180 BigInteger v = u1.multiply(u2).mod(p).mod(q);
181
182 return v.equals(r);
183 }
184
185 public static DSASignature generateSignature(byte[] message, DSAPrivateKey pk, SecureRandom rnd) throws IOException {
186 SHA1 md = new SHA1();
187 md.update(message);
188 byte[] sha_message = new byte[md.getDigestLength()];
189 try {
190 md.digest(sha_message);
191 }
192 catch(DigestException e) {
193 throw new IOException(e);
194 }
195
196 BigInteger m = new BigInteger(1, sha_message);
197 BigInteger k;
198 int qBitLength = pk.getQ().bitLength();
199
200 do {
201 k = new BigInteger(qBitLength, rnd);
202 }
203 while(k.compareTo(pk.getQ()) >= 0);
204
205 BigInteger r = pk.getG().modPow(k, pk.getP()).mod(pk.getQ());
206
207 k = k.modInverse(pk.getQ()).multiply(m.add((pk).getX().multiply(r)));
208
209 BigInteger s = k.mod(pk.getQ());
210
211 return new DSASignature(r, s);
212 }
213 }