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comparison src/ch/ethz/ssh2/signature/RSASHA1Verify.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
11 import ch.ethz.ssh2.PacketFormatException;
12 import ch.ethz.ssh2.crypto.SimpleDERReader;
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 * RSASHA1Verify.
20 *
21 * @author Christian Plattner
22 * @version $Id: RSASHA1Verify.java 154 2014-04-28 11:45:02Z dkocher@sudo.ch $
23 */
24 public class RSASHA1Verify {
25 private static final Logger log = Logger.getLogger(RSASHA1Verify.class);
26
27 public static RSAPublicKey decodeSSHRSAPublicKey(byte[] key) throws IOException {
28 TypesReader tr = new TypesReader(key);
29
30 String key_format = tr.readString();
31
32 if(!key_format.equals("ssh-rsa")) {
33 throw new IllegalArgumentException("Not a ssh-rsa public key");
34 }
35
36 BigInteger e = tr.readMPINT();
37 BigInteger n = tr.readMPINT();
38
39 if(tr.remain() != 0) {
40 throw new PacketFormatException("Padding in RSA public key");
41 }
42
43 return new RSAPublicKey(e, n);
44 }
45
46 public static byte[] encodeSSHRSAPublicKey(RSAPublicKey pk) throws IOException {
47 TypesWriter tw = new TypesWriter();
48
49 tw.writeString("ssh-rsa");
50 tw.writeMPInt(pk.getE());
51 tw.writeMPInt(pk.getN());
52
53 return tw.getBytes();
54 }
55
56 public static RSASignature decodeSSHRSASignature(byte[] sig) throws IOException {
57 TypesReader tr = new TypesReader(sig);
58
59 String sig_format = tr.readString();
60
61 if(!sig_format.equals("ssh-rsa")) {
62 throw new PacketFormatException("Peer sent wrong signature format");
63 }
64
65 /* S is NOT an MPINT. "The value for 'rsa_signature_blob' is encoded as a string
66 * containing s (which is an integer, without lengths or padding, unsigned and in
67 * network byte order)." See also below.
68 */
69
70 byte[] s = tr.readByteString();
71
72 if(s.length == 0) {
73 throw new PacketFormatException("Error in RSA signature, S is empty.");
74 }
75
76 if(log.isDebugEnabled()) {
77 log.debug("Decoding ssh-rsa signature string (length: " + s.length + ")");
78 }
79
80 if(tr.remain() != 0) {
81 throw new PacketFormatException("Padding in RSA signature!");
82 }
83
84 return new RSASignature(new BigInteger(1, s));
85 }
86
87 public static byte[] encodeSSHRSASignature(RSASignature sig) throws IOException {
88 TypesWriter tw = new TypesWriter();
89
90 tw.writeString("ssh-rsa");
91
92 /* S is NOT an MPINT. "The value for 'rsa_signature_blob' is encoded as a string
93 * containing s (which is an integer, without lengths or padding, unsigned and in
94 * network byte order)."
95 */
96
97 byte[] s = sig.getS().toByteArray();
98
99 /* Remove first zero sign byte, if present */
100
101 if((s.length > 1) && (s[0] == 0x00)) {
102 tw.writeString(s, 1, s.length - 1);
103 }
104 else {
105 tw.writeString(s, 0, s.length);
106 }
107
108 return tw.getBytes();
109 }
110
111 public static RSASignature generateSignature(byte[] message, RSAPrivateKey pk) throws IOException {
112 SHA1 md = new SHA1();
113 md.update(message);
114 byte[] sha_message = new byte[md.getDigestLength()];
115 try {
116 md.digest(sha_message);
117 }
118 catch(DigestException e) {
119 throw new IOException(e);
120 }
121
122 byte[] der_header = new byte[]{0x30, 0x21, 0x30, 0x09, 0x06, 0x05, 0x2b, 0x0e, 0x03, 0x02, 0x1a, 0x05, 0x00,
123 0x04, 0x14};
124
125 int rsa_block_len = (pk.getN().bitLength() + 7) / 8;
126
127 int num_pad = rsa_block_len - (2 + der_header.length + sha_message.length) - 1;
128
129 if(num_pad < 8) {
130 throw new PacketFormatException("Cannot sign with RSA, message too long");
131 }
132
133 byte[] sig = new byte[der_header.length + sha_message.length + 2 + num_pad];
134
135 sig[0] = 0x01;
136
137 for(int i = 0; i < num_pad; i++) {
138 sig[i + 1] = (byte) 0xff;
139 }
140
141 sig[num_pad + 1] = 0x00;
142
143 System.arraycopy(der_header, 0, sig, 2 + num_pad, der_header.length);
144 System.arraycopy(sha_message, 0, sig, 2 + num_pad + der_header.length, sha_message.length);
145
146 BigInteger m = new BigInteger(1, sig);
147
148 BigInteger s = m.modPow(pk.getD(), pk.getN());
149
150 return new RSASignature(s);
151 }
152
153 public static boolean verifySignature(byte[] message, RSASignature ds, RSAPublicKey dpk) throws IOException {
154 SHA1 md = new SHA1();
155 md.update(message);
156 byte[] sha_message = new byte[md.getDigestLength()];
157 try {
158 md.digest(sha_message);
159 }
160 catch(DigestException e) {
161 throw new IOException(e);
162 }
163
164 BigInteger n = dpk.getN();
165 BigInteger e = dpk.getE();
166 BigInteger s = ds.getS();
167
168 if(n.compareTo(s) <= 0) {
169 log.warning("ssh-rsa signature: n.compareTo(s) <= 0");
170 return false;
171 }
172
173 int rsa_block_len = (n.bitLength() + 7) / 8;
174
175 /* And now the show begins */
176
177 if(rsa_block_len < 1) {
178 log.warning("ssh-rsa signature: rsa_block_len < 1");
179 return false;
180 }
181
182 byte[] v = s.modPow(e, n).toByteArray();
183
184 int startpos = 0;
185
186 if((v.length > 0) && (v[0] == 0x00)) {
187 startpos++;
188 }
189
190 if((v.length - startpos) != (rsa_block_len - 1)) {
191 log.warning("ssh-rsa signature: (v.length - startpos) != (rsa_block_len - 1)");
192 return false;
193 }
194
195 if(v[startpos] != 0x01) {
196 log.warning("ssh-rsa signature: v[startpos] != 0x01");
197 return false;
198 }
199
200 int pos = startpos + 1;
201
202 while(true) {
203 if(pos >= v.length) {
204 log.warning("ssh-rsa signature: pos >= v.length");
205 return false;
206 }
207 if(v[pos] == 0x00) {
208 break;
209 }
210 if(v[pos] != (byte) 0xff) {
211 log.warning("ssh-rsa signature: v[pos] != (byte) 0xff");
212 return false;
213 }
214 pos++;
215 }
216
217 int num_pad = pos - (startpos + 1);
218
219 if(num_pad < 8) {
220 log.warning("ssh-rsa signature: num_pad < 8");
221 return false;
222 }
223
224 pos++;
225
226 if(pos >= v.length) {
227 log.warning("ssh-rsa signature: pos >= v.length");
228 return false;
229 }
230
231 SimpleDERReader dr = new SimpleDERReader(v, pos, v.length - pos);
232
233 byte[] seq = dr.readSequenceAsByteArray();
234
235 if(dr.available() != 0) {
236 log.warning("ssh-rsa signature: dr.available() != 0");
237 return false;
238 }
239
240 dr.resetInput(seq);
241
242 /* Read digestAlgorithm */
243
244 byte digestAlgorithm[] = dr.readSequenceAsByteArray();
245
246 /* Inspired by RFC 3347, however, ignoring the comment regarding old BER based implementations */
247
248 if((digestAlgorithm.length < 8) || (digestAlgorithm.length > 9)) {
249 log.warning("ssh-rsa signature: (digestAlgorithm.length < 8) || (digestAlgorithm.length > 9)");
250 return false;
251 }
252
253 byte[] digestAlgorithm_sha1 = new byte[]{0x06, 0x05, 0x2b, 0x0e, 0x03, 0x02, 0x1a, 0x05, 0x00};
254
255 for(int i = 0; i < digestAlgorithm.length; i++) {
256 if(digestAlgorithm[i] != digestAlgorithm_sha1[i]) {
257 log.warning("ssh-rsa signature: digestAlgorithm[i] != digestAlgorithm_sha1[i]");
258 return false;
259 }
260 }
261
262 byte[] digest = dr.readOctetString();
263
264 if(dr.available() != 0) {
265 log.warning("ssh-rsa signature: dr.available() != 0 (II)");
266 return false;
267 }
268
269 if(digest.length != sha_message.length) {
270 log.warning("ssh-rsa signature: digest.length != sha_message.length");
271 return false;
272 }
273
274 for(int i = 0; i < sha_message.length; i++) {
275 if(sha_message[i] != digest[i]) {
276 log.warning("ssh-rsa signature: sha_message[i] != digest[i]");
277 return false;
278 }
279 }
280
281 return true;
282 }
283 }