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1 | #include <stdio.h> |
2 | #include <stdlib.h> |
65a22376 |
3 | #include <assert.h> |
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4 | |
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5 | #include "ssh.h" |
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6 | #include "misc.h" |
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7 | |
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8 | #define GET_32BIT(cp) \ |
9 | (((unsigned long)(unsigned char)(cp)[0] << 24) | \ |
10 | ((unsigned long)(unsigned char)(cp)[1] << 16) | \ |
11 | ((unsigned long)(unsigned char)(cp)[2] << 8) | \ |
12 | ((unsigned long)(unsigned char)(cp)[3])) |
13 | |
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14 | #define PUT_32BIT(cp, value) { \ |
15 | (cp)[0] = (unsigned char)((value) >> 24); \ |
16 | (cp)[1] = (unsigned char)((value) >> 16); \ |
17 | (cp)[2] = (unsigned char)((value) >> 8); \ |
18 | (cp)[3] = (unsigned char)(value); } |
19 | |
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20 | static void sha_mpint(SHA_State * s, Bignum b) |
21 | { |
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22 | unsigned char lenbuf[4]; |
23 | int len; |
24 | len = (bignum_bitcount(b) + 8) / 8; |
25 | PUT_32BIT(lenbuf, len); |
26 | SHA_Bytes(s, lenbuf, 4); |
27 | while (len-- > 0) { |
28 | lenbuf[0] = bignum_byte(b, len); |
29 | SHA_Bytes(s, lenbuf, 1); |
30 | } |
31 | memset(lenbuf, 0, sizeof(lenbuf)); |
32 | } |
33 | |
34 | static void sha512_mpint(SHA512_State * s, Bignum b) |
35 | { |
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36 | unsigned char lenbuf[4]; |
37 | int len; |
38 | len = (bignum_bitcount(b) + 8) / 8; |
39 | PUT_32BIT(lenbuf, len); |
40 | SHA512_Bytes(s, lenbuf, 4); |
41 | while (len-- > 0) { |
42 | lenbuf[0] = bignum_byte(b, len); |
43 | SHA512_Bytes(s, lenbuf, 1); |
44 | } |
45 | memset(lenbuf, 0, sizeof(lenbuf)); |
46 | } |
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47 | |
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48 | static void getstring(char **data, int *datalen, char **p, int *length) |
49 | { |
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50 | *p = NULL; |
51 | if (*datalen < 4) |
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52 | return; |
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53 | *length = GET_32BIT(*data); |
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54 | *datalen -= 4; |
55 | *data += 4; |
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56 | if (*datalen < *length) |
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57 | return; |
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58 | *p = *data; |
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59 | *data += *length; |
60 | *datalen -= *length; |
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61 | } |
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62 | static Bignum getmp(char **data, int *datalen) |
63 | { |
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64 | char *p; |
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65 | int length; |
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66 | Bignum b; |
67 | |
68 | getstring(data, datalen, &p, &length); |
69 | if (!p) |
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70 | return NULL; |
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71 | if (p[0] & 0x80) |
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72 | return NULL; /* negative mp */ |
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73 | b = bignum_from_bytes(p, length); |
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74 | return b; |
75 | } |
76 | |
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77 | static Bignum get160(char **data, int *datalen) |
78 | { |
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79 | Bignum b; |
80 | |
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81 | b = bignum_from_bytes(*data, 20); |
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82 | *data += 20; |
83 | *datalen -= 20; |
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84 | |
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85 | return b; |
86 | } |
87 | |
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88 | static void *dss_newkey(char *data, int len) |
89 | { |
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90 | char *p; |
91 | int slen; |
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92 | struct dss_key *dss; |
93 | |
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94 | dss = smalloc(sizeof(struct dss_key)); |
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95 | if (!dss) |
96 | return NULL; |
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97 | getstring(&data, &len, &p, &slen); |
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98 | |
99 | #ifdef DEBUG_DSS |
100 | { |
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101 | int i; |
102 | printf("key:"); |
103 | for (i = 0; i < len; i++) |
104 | printf(" %02x", (unsigned char) (data[i])); |
105 | printf("\n"); |
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106 | } |
107 | #endif |
108 | |
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109 | if (!p || memcmp(p, "ssh-dss", 7)) { |
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110 | sfree(dss); |
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111 | return NULL; |
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112 | } |
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113 | dss->p = getmp(&data, &len); |
114 | dss->q = getmp(&data, &len); |
115 | dss->g = getmp(&data, &len); |
116 | dss->y = getmp(&data, &len); |
117 | |
118 | return dss; |
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119 | } |
120 | |
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121 | static void dss_freekey(void *key) |
122 | { |
123 | struct dss_key *dss = (struct dss_key *) key; |
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124 | freebn(dss->p); |
125 | freebn(dss->q); |
126 | freebn(dss->g); |
127 | freebn(dss->y); |
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128 | sfree(dss); |
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129 | } |
130 | |
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131 | static char *dss_fmtkey(void *key) |
132 | { |
133 | struct dss_key *dss = (struct dss_key *) key; |
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134 | char *p; |
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135 | int len, i, pos, nibbles; |
136 | static const char hex[] = "0123456789abcdef"; |
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137 | if (!dss->p) |
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138 | return NULL; |
139 | len = 8 + 4 + 1; /* 4 x "0x", punctuation, \0 */ |
140 | len += 4 * (bignum_bitcount(dss->p) + 15) / 16; |
141 | len += 4 * (bignum_bitcount(dss->q) + 15) / 16; |
142 | len += 4 * (bignum_bitcount(dss->g) + 15) / 16; |
143 | len += 4 * (bignum_bitcount(dss->y) + 15) / 16; |
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144 | p = smalloc(len); |
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145 | if (!p) |
146 | return NULL; |
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147 | |
148 | pos = 0; |
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149 | pos += sprintf(p + pos, "0x"); |
150 | nibbles = (3 + bignum_bitcount(dss->p)) / 4; |
151 | if (nibbles < 1) |
152 | nibbles = 1; |
153 | for (i = nibbles; i--;) |
154 | p[pos++] = |
155 | hex[(bignum_byte(dss->p, i / 2) >> (4 * (i % 2))) & 0xF]; |
156 | pos += sprintf(p + pos, ",0x"); |
157 | nibbles = (3 + bignum_bitcount(dss->q)) / 4; |
158 | if (nibbles < 1) |
159 | nibbles = 1; |
160 | for (i = nibbles; i--;) |
161 | p[pos++] = |
162 | hex[(bignum_byte(dss->q, i / 2) >> (4 * (i % 2))) & 0xF]; |
163 | pos += sprintf(p + pos, ",0x"); |
164 | nibbles = (3 + bignum_bitcount(dss->g)) / 4; |
165 | if (nibbles < 1) |
166 | nibbles = 1; |
167 | for (i = nibbles; i--;) |
168 | p[pos++] = |
169 | hex[(bignum_byte(dss->g, i / 2) >> (4 * (i % 2))) & 0xF]; |
170 | pos += sprintf(p + pos, ",0x"); |
171 | nibbles = (3 + bignum_bitcount(dss->y)) / 4; |
172 | if (nibbles < 1) |
173 | nibbles = 1; |
174 | for (i = nibbles; i--;) |
175 | p[pos++] = |
176 | hex[(bignum_byte(dss->y, i / 2) >> (4 * (i % 2))) & 0xF]; |
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177 | p[pos] = '\0'; |
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178 | return p; |
179 | } |
180 | |
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181 | static char *dss_fingerprint(void *key) |
182 | { |
183 | struct dss_key *dss = (struct dss_key *) key; |
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184 | struct MD5Context md5c; |
185 | unsigned char digest[16], lenbuf[4]; |
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186 | char buffer[16 * 3 + 40]; |
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187 | char *ret; |
188 | int numlen, i; |
189 | |
190 | MD5Init(&md5c); |
191 | MD5Update(&md5c, "\0\0\0\7ssh-dss", 11); |
192 | |
193 | #define ADD_BIGNUM(bignum) \ |
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194 | numlen = (bignum_bitcount(bignum)+8)/8; \ |
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195 | PUT_32BIT(lenbuf, numlen); MD5Update(&md5c, lenbuf, 4); \ |
196 | for (i = numlen; i-- ;) { \ |
197 | unsigned char c = bignum_byte(bignum, i); \ |
198 | MD5Update(&md5c, &c, 1); \ |
199 | } |
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200 | ADD_BIGNUM(dss->p); |
201 | ADD_BIGNUM(dss->q); |
202 | ADD_BIGNUM(dss->g); |
203 | ADD_BIGNUM(dss->y); |
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204 | #undef ADD_BIGNUM |
205 | |
206 | MD5Final(digest, &md5c); |
207 | |
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208 | sprintf(buffer, "ssh-dss %d ", bignum_bitcount(dss->p)); |
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209 | for (i = 0; i < 16; i++) |
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210 | sprintf(buffer + strlen(buffer), "%s%02x", i ? ":" : "", |
211 | digest[i]); |
212 | ret = smalloc(strlen(buffer) + 1); |
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213 | if (ret) |
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214 | strcpy(ret, buffer); |
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215 | return ret; |
216 | } |
217 | |
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218 | static int dss_verifysig(void *key, char *sig, int siglen, |
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219 | char *data, int datalen) |
220 | { |
221 | struct dss_key *dss = (struct dss_key *) key; |
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222 | char *p; |
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223 | int slen; |
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224 | char hash[20]; |
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225 | Bignum r, s, w, gu1p, yu2p, gu1yu2p, u1, u2, sha, v; |
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226 | int ret; |
227 | |
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228 | if (!dss->p) |
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229 | return 0; |
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230 | |
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231 | #ifdef DEBUG_DSS |
232 | { |
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233 | int i; |
234 | printf("sig:"); |
235 | for (i = 0; i < siglen; i++) |
236 | printf(" %02x", (unsigned char) (sig[i])); |
237 | printf("\n"); |
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238 | } |
239 | #endif |
7f7837c8 |
240 | /* |
241 | * Commercial SSH (2.0.13) and OpenSSH disagree over the format |
242 | * of a DSA signature. OpenSSH is in line with the IETF drafts: |
243 | * it uses a string "ssh-dss", followed by a 40-byte string |
244 | * containing two 160-bit integers end-to-end. Commercial SSH |
245 | * can't be bothered with the header bit, and considers a DSA |
246 | * signature blob to be _just_ the 40-byte string containing |
247 | * the two 160-bit integers. We tell them apart by measuring |
248 | * the length: length 40 means the commercial-SSH bug, anything |
249 | * else is assumed to be IETF-compliant. |
250 | */ |
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251 | if (siglen != 40) { /* bug not present; read admin fields */ |
252 | getstring(&sig, &siglen, &p, &slen); |
253 | if (!p || slen != 7 || memcmp(p, "ssh-dss", 7)) { |
254 | return 0; |
255 | } |
256 | sig += 4, siglen -= 4; /* skip yet another length field */ |
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257 | } |
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258 | r = get160(&sig, &siglen); |
259 | s = get160(&sig, &siglen); |
260 | if (!r || !s) |
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261 | return 0; |
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262 | |
263 | /* |
264 | * Step 1. w <- s^-1 mod q. |
265 | */ |
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266 | w = modinv(s, dss->q); |
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267 | |
268 | /* |
269 | * Step 2. u1 <- SHA(message) * w mod q. |
270 | */ |
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271 | SHA_Simple(data, datalen, hash); |
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272 | p = hash; |
273 | slen = 20; |
274 | sha = get160(&p, &slen); |
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275 | u1 = modmul(sha, w, dss->q); |
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276 | |
277 | /* |
278 | * Step 3. u2 <- r * w mod q. |
279 | */ |
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280 | u2 = modmul(r, w, dss->q); |
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281 | |
282 | /* |
283 | * Step 4. v <- (g^u1 * y^u2 mod p) mod q. |
284 | */ |
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285 | gu1p = modpow(dss->g, u1, dss->p); |
e055a386 |
286 | yu2p = modpow(dss->y, u2, dss->p); |
e055a386 |
287 | gu1yu2p = modmul(gu1p, yu2p, dss->p); |
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288 | v = modmul(gu1yu2p, One, dss->q); |
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289 | |
290 | /* |
291 | * Step 5. v should now be equal to r. |
292 | */ |
293 | |
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294 | ret = !bignum_cmp(v, r); |
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295 | |
296 | freebn(w); |
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297 | freebn(sha); |
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298 | freebn(gu1p); |
299 | freebn(yu2p); |
300 | freebn(gu1yu2p); |
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301 | freebn(v); |
302 | freebn(r); |
303 | freebn(s); |
304 | |
305 | return ret; |
306 | } |
307 | |
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308 | static unsigned char *dss_public_blob(void *key, int *len) |
309 | { |
310 | struct dss_key *dss = (struct dss_key *) key; |
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311 | int plen, qlen, glen, ylen, bloblen; |
312 | int i; |
313 | unsigned char *blob, *p; |
314 | |
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315 | plen = (bignum_bitcount(dss->p) + 8) / 8; |
316 | qlen = (bignum_bitcount(dss->q) + 8) / 8; |
317 | glen = (bignum_bitcount(dss->g) + 8) / 8; |
318 | ylen = (bignum_bitcount(dss->y) + 8) / 8; |
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319 | |
320 | /* |
321 | * string "ssh-dss", mpint p, mpint q, mpint g, mpint y. Total |
322 | * 27 + sum of lengths. (five length fields, 20+7=27). |
323 | */ |
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324 | bloblen = 27 + plen + qlen + glen + ylen; |
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325 | blob = smalloc(bloblen); |
326 | p = blob; |
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327 | PUT_32BIT(p, 7); |
328 | p += 4; |
329 | memcpy(p, "ssh-dss", 7); |
330 | p += 7; |
331 | PUT_32BIT(p, plen); |
332 | p += 4; |
333 | for (i = plen; i--;) |
334 | *p++ = bignum_byte(dss->p, i); |
335 | PUT_32BIT(p, qlen); |
336 | p += 4; |
337 | for (i = qlen; i--;) |
338 | *p++ = bignum_byte(dss->q, i); |
339 | PUT_32BIT(p, glen); |
340 | p += 4; |
341 | for (i = glen; i--;) |
342 | *p++ = bignum_byte(dss->g, i); |
343 | PUT_32BIT(p, ylen); |
344 | p += 4; |
345 | for (i = ylen; i--;) |
346 | *p++ = bignum_byte(dss->y, i); |
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347 | assert(p == blob + bloblen); |
348 | *len = bloblen; |
349 | return blob; |
350 | } |
351 | |
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352 | static unsigned char *dss_private_blob(void *key, int *len) |
353 | { |
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354 | struct dss_key *dss = (struct dss_key *) key; |
355 | int xlen, bloblen; |
356 | int i; |
357 | unsigned char *blob, *p; |
358 | SHA_State s; |
359 | unsigned char digest[20]; |
360 | |
361 | xlen = (bignum_bitcount(dss->x) + 8) / 8; |
362 | |
363 | /* |
364 | * mpint x, string[20] the SHA of p||q||g. Total 28 + xlen. |
365 | * (two length fields and twenty bytes, 20+8=28). |
366 | */ |
367 | bloblen = 28 + xlen; |
368 | blob = smalloc(bloblen); |
369 | p = blob; |
370 | PUT_32BIT(p, xlen); |
371 | p += 4; |
372 | for (i = xlen; i--;) |
373 | *p++ = bignum_byte(dss->x, i); |
374 | PUT_32BIT(p, 20); |
375 | SHA_Init(&s); |
376 | sha_mpint(&s, dss->p); |
377 | sha_mpint(&s, dss->q); |
378 | sha_mpint(&s, dss->g); |
379 | SHA_Final(&s, digest); |
380 | p += 4; |
381 | for (i = 0; i < 20; i++) |
382 | *p++ = digest[i]; |
383 | assert(p == blob + bloblen); |
384 | *len = bloblen; |
385 | return blob; |
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386 | } |
387 | |
388 | static void *dss_createkey(unsigned char *pub_blob, int pub_len, |
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389 | unsigned char *priv_blob, int priv_len) |
390 | { |
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391 | struct dss_key *dss; |
392 | char *pb = (char *) priv_blob; |
393 | char *hash; |
394 | int hashlen; |
395 | SHA_State s; |
396 | unsigned char digest[20]; |
397 | Bignum ytest; |
398 | |
399 | dss = dss_newkey((char *) pub_blob, pub_len); |
400 | dss->x = getmp(&pb, &priv_len); |
401 | getstring(&pb, &priv_len, &hash, &hashlen); |
402 | |
403 | /* |
404 | * Verify details of the key. First check that the hash is |
405 | * indeed a hash of p||q||g. |
406 | */ |
407 | if (hashlen != 20) { |
408 | dss_freekey(dss); |
409 | return NULL; |
410 | } |
411 | SHA_Init(&s); |
412 | sha_mpint(&s, dss->p); |
413 | sha_mpint(&s, dss->q); |
414 | sha_mpint(&s, dss->g); |
415 | SHA_Final(&s, digest); |
416 | if (0 != memcmp(hash, digest, 20)) { |
417 | dss_freekey(dss); |
418 | return NULL; |
419 | } |
420 | |
421 | /* |
422 | * Now ensure g^x mod p really is y. |
423 | */ |
424 | ytest = modpow(dss->g, dss->x, dss->p); |
425 | if (0 != bignum_cmp(ytest, dss->y)) { |
426 | dss_freekey(dss); |
427 | return NULL; |
428 | } |
429 | freebn(ytest); |
430 | |
431 | return dss; |
65a22376 |
432 | } |
433 | |
32874aea |
434 | static void *dss_openssh_createkey(unsigned char **blob, int *len) |
435 | { |
5c72ca61 |
436 | char **b = (char **) blob; |
437 | struct dss_key *dss; |
438 | |
439 | dss = smalloc(sizeof(struct dss_key)); |
440 | if (!dss) |
441 | return NULL; |
442 | |
443 | dss->p = getmp(b, len); |
444 | dss->q = getmp(b, len); |
445 | dss->g = getmp(b, len); |
446 | dss->y = getmp(b, len); |
447 | dss->x = getmp(b, len); |
448 | |
449 | if (!dss->p || !dss->q || !dss->g || !dss->y || !dss->x) { |
450 | sfree(dss->p); |
451 | sfree(dss->q); |
452 | sfree(dss->g); |
453 | sfree(dss->y); |
454 | sfree(dss->x); |
455 | sfree(dss); |
456 | return NULL; |
457 | } |
458 | |
459 | return dss; |
45cebe79 |
460 | } |
461 | |
32874aea |
462 | static int dss_openssh_fmtkey(void *key, unsigned char *blob, int len) |
463 | { |
5c72ca61 |
464 | struct dss_key *dss = (struct dss_key *) key; |
465 | int bloblen, i; |
466 | |
467 | bloblen = |
468 | ssh2_bignum_length(dss->p) + |
469 | ssh2_bignum_length(dss->q) + |
470 | ssh2_bignum_length(dss->g) + |
471 | ssh2_bignum_length(dss->y) + |
472 | ssh2_bignum_length(dss->x); |
473 | |
474 | if (bloblen > len) |
475 | return bloblen; |
476 | |
477 | bloblen = 0; |
478 | #define ENC(x) \ |
479 | PUT_32BIT(blob+bloblen, ssh2_bignum_length((x))-4); bloblen += 4; \ |
480 | for (i = ssh2_bignum_length((x))-4; i-- ;) blob[bloblen++]=bignum_byte((x),i); |
481 | ENC(dss->p); |
482 | ENC(dss->q); |
483 | ENC(dss->g); |
484 | ENC(dss->y); |
485 | ENC(dss->x); |
486 | |
487 | return bloblen; |
ddecd643 |
488 | } |
489 | |
32874aea |
490 | unsigned char *dss_sign(void *key, char *data, int datalen, int *siglen) |
491 | { |
5c72ca61 |
492 | /* |
493 | * The basic DSS signing algorithm is: |
494 | * |
495 | * - invent a random k between 1 and q-1 (exclusive). |
496 | * - Compute r = (g^k mod p) mod q. |
497 | * - Compute s = k^-1 * (hash + x*r) mod q. |
498 | * |
499 | * This has the dangerous properties that: |
500 | * |
501 | * - if an attacker in possession of the public key _and_ the |
502 | * signature (for example, the host you just authenticated |
503 | * to) can guess your k, he can reverse the computation of s |
504 | * and work out x = r^-1 * (s*k - hash) mod q. That is, he |
505 | * can deduce the private half of your key, and masquerade |
506 | * as you for as long as the key is still valid. |
507 | * |
508 | * - since r is a function purely of k and the public key, if |
509 | * the attacker only has a _range of possibilities_ for k |
510 | * it's easy for him to work through them all and check each |
511 | * one against r; he'll never be unsure of whether he's got |
512 | * the right one. |
513 | * |
514 | * - if you ever sign two different hashes with the same k, it |
515 | * will be immediately obvious because the two signatures |
516 | * will have the same r, and moreover an attacker in |
517 | * possession of both signatures (and the public key of |
518 | * course) can compute k = (hash1-hash2) * (s1-s2)^-1 mod q, |
519 | * and from there deduce x as before. |
520 | * |
521 | * - the Bleichenbacher attack on DSA makes use of methods of |
522 | * generating k which are significantly non-uniformly |
523 | * distributed; in particular, generating a 160-bit random |
524 | * number and reducing it mod q is right out. |
525 | * |
526 | * For this reason we must be pretty careful about how we |
527 | * generate our k. Since this code runs on Windows, with no |
528 | * particularly good system entropy sources, we can't trust our |
529 | * RNG itself to produce properly unpredictable data. Hence, we |
530 | * use a totally different scheme instead. |
531 | * |
532 | * What we do is to take a SHA-512 (_big_) hash of the private |
533 | * key x, and then feed this into another SHA-512 hash that |
534 | * also includes the message hash being signed. That is: |
535 | * |
536 | * proto_k = SHA512 ( SHA512(x) || SHA160(message) ) |
537 | * |
538 | * This number is 512 bits long, so reducing it mod q won't be |
539 | * noticeably non-uniform. So |
540 | * |
541 | * k = proto_k mod q |
542 | * |
543 | * This has the interesting property that it's _deterministic_: |
544 | * signing the same hash twice with the same key yields the |
545 | * same signature. |
546 | * |
5ced2a02 |
547 | * Despite this determinism, it's still not predictable to an |
548 | * attacker, because in order to repeat the SHA-512 |
549 | * construction that created it, the attacker would have to |
550 | * know the private key value x - and by assumption he doesn't, |
551 | * because if he knew that he wouldn't be attacking k! |
552 | * |
553 | * (This trick doesn't, _per se_, protect against reuse of k. |
554 | * Reuse of k is left to chance; all it does is prevent |
555 | * _excessively high_ chances of reuse of k due to entropy |
556 | * problems.) |
5c72ca61 |
557 | * |
558 | * Thanks to Colin Plumb for the general idea of using x to |
559 | * ensure k is hard to guess, and to the Cambridge University |
560 | * Computer Security Group for helping to argue out all the |
561 | * fine details. |
562 | */ |
563 | struct dss_key *dss = (struct dss_key *) key; |
564 | SHA512_State ss; |
565 | unsigned char digest[20], digest512[64]; |
566 | Bignum proto_k, k, gkp, hash, kinv, hxr, r, s; |
567 | unsigned char *bytes; |
568 | int nbytes, i; |
569 | |
570 | SHA_Simple(data, datalen, digest); |
571 | |
572 | /* |
573 | * Hash some identifying text plus x. |
574 | */ |
575 | SHA512_Init(&ss); |
576 | SHA512_Bytes(&ss, "DSA deterministic k generator", 30); |
577 | sha512_mpint(&ss, dss->x); |
578 | SHA512_Final(&ss, digest512); |
579 | |
580 | /* |
581 | * Now hash that digest plus the message hash. |
582 | */ |
583 | SHA512_Init(&ss); |
584 | SHA512_Bytes(&ss, digest512, sizeof(digest512)); |
585 | SHA512_Bytes(&ss, digest, sizeof(digest)); |
586 | SHA512_Final(&ss, digest512); |
587 | |
588 | memset(&ss, 0, sizeof(ss)); |
589 | |
590 | /* |
591 | * Now convert the result into a bignum, and reduce it mod q. |
592 | */ |
593 | proto_k = bignum_from_bytes(digest512, 64); |
594 | k = bigmod(proto_k, dss->q); |
595 | freebn(proto_k); |
596 | |
597 | memset(digest512, 0, sizeof(digest512)); |
598 | |
599 | /* |
600 | * Now we have k, so just go ahead and compute the signature. |
601 | */ |
602 | gkp = modpow(dss->g, k, dss->p); /* g^k mod p */ |
603 | r = bigmod(gkp, dss->q); /* r = (g^k mod p) mod q */ |
604 | freebn(gkp); |
605 | |
606 | hash = bignum_from_bytes(digest, 20); |
607 | kinv = modinv(k, dss->q); /* k^-1 mod q */ |
608 | hxr = bigmuladd(dss->x, r, hash); /* hash + x*r */ |
609 | s = modmul(kinv, hxr, dss->q); /* s = k^-1 * (hash + x*r) mod q */ |
610 | freebn(hxr); |
611 | freebn(kinv); |
612 | freebn(hash); |
613 | |
614 | /* |
615 | * Signature blob is |
616 | * |
617 | * string "ssh-dss" |
618 | * string two 20-byte numbers r and s, end to end |
619 | * |
620 | * i.e. 4+7 + 4+40 bytes. |
621 | */ |
622 | nbytes = 4 + 7 + 4 + 40; |
623 | bytes = smalloc(nbytes); |
624 | PUT_32BIT(bytes, 7); |
625 | memcpy(bytes + 4, "ssh-dss", 7); |
626 | PUT_32BIT(bytes + 4 + 7, 40); |
627 | for (i = 0; i < 20; i++) { |
628 | bytes[4 + 7 + 4 + i] = bignum_byte(r, 19 - i); |
629 | bytes[4 + 7 + 4 + 20 + i] = bignum_byte(s, 19 - i); |
630 | } |
631 | freebn(r); |
632 | freebn(s); |
633 | |
634 | *siglen = nbytes; |
635 | return bytes; |
e055a386 |
636 | } |
637 | |
65a22376 |
638 | const struct ssh_signkey ssh_dss = { |
e055a386 |
639 | dss_newkey, |
640 | dss_freekey, |
7cca0d81 |
641 | dss_fmtkey, |
65a22376 |
642 | dss_public_blob, |
643 | dss_private_blob, |
644 | dss_createkey, |
45cebe79 |
645 | dss_openssh_createkey, |
ddecd643 |
646 | dss_openssh_fmtkey, |
d5859615 |
647 | dss_fingerprint, |
7cca0d81 |
648 | dss_verifysig, |
e055a386 |
649 | dss_sign, |
d5859615 |
650 | "ssh-dss", |
651 | "dss" |
e5574168 |
652 | }; |