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1 | /* | |
2 | * Copyright (c) 2000 Markus Friedl. All rights reserved. | |
3 | * | |
4 | * Redistribution and use in source and binary forms, with or without | |
5 | * modification, are permitted provided that the following conditions | |
6 | * are met: | |
7 | * 1. Redistributions of source code must retain the above copyright | |
8 | * notice, this list of conditions and the following disclaimer. | |
9 | * 2. Redistributions in binary form must reproduce the above copyright | |
10 | * notice, this list of conditions and the following disclaimer in the | |
11 | * documentation and/or other materials provided with the distribution. | |
12 | * 3. All advertising materials mentioning features or use of this software | |
13 | * must display the following acknowledgement: | |
14 | * This product includes software developed by Markus Friedl. | |
15 | * 4. The name of the author may not be used to endorse or promote products | |
16 | * derived from this software without specific prior written permission. | |
17 | * | |
18 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
19 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
20 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
21 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
22 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
23 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
24 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
25 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
26 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
27 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
28 | */ | |
29 | ||
30 | #include "includes.h" | |
31 | RCSID("$Id$"); | |
32 | ||
33 | #include "ssh.h" | |
34 | #include "xmalloc.h" | |
35 | #include "buffer.h" | |
36 | #include "bufaux.h" | |
37 | #include "compat.h" | |
38 | ||
39 | #include <openssl/bn.h> | |
40 | #include <openssl/dh.h> | |
41 | #include <openssl/rsa.h> | |
42 | #include <openssl/dsa.h> | |
43 | #include <openssl/evp.h> | |
44 | #include <openssl/bio.h> | |
45 | #include <openssl/pem.h> | |
46 | ||
47 | #include <openssl/hmac.h> | |
48 | #include "kex.h" | |
49 | #include "key.h" | |
50 | #include "uuencode.h" | |
51 | ||
52 | #define INTBLOB_LEN 20 | |
53 | #define SIGBLOB_LEN (2*INTBLOB_LEN) | |
54 | ||
55 | Key * | |
56 | dsa_key_from_blob( | |
57 | char *blob, int blen) | |
58 | { | |
59 | Buffer b; | |
60 | char *ktype; | |
61 | int rlen; | |
62 | DSA *dsa; | |
63 | Key *key; | |
64 | ||
65 | #ifdef DEBUG_DSS | |
66 | dump_base64(stderr, blob, blen); | |
67 | #endif | |
68 | /* fetch & parse DSA/DSS pubkey */ | |
69 | key = key_new(KEY_DSA); | |
70 | dsa = key->dsa; | |
71 | buffer_init(&b); | |
72 | buffer_append(&b, blob, blen); | |
73 | ktype = buffer_get_string(&b, NULL); | |
74 | if (strcmp(KEX_DSS, ktype) != 0) { | |
75 | error("dsa_key_from_blob: cannot handle type %s", ktype); | |
76 | key_free(key); | |
77 | return NULL; | |
78 | } | |
79 | buffer_get_bignum2(&b, dsa->p); | |
80 | buffer_get_bignum2(&b, dsa->q); | |
81 | buffer_get_bignum2(&b, dsa->g); | |
82 | buffer_get_bignum2(&b, dsa->pub_key); | |
83 | rlen = buffer_len(&b); | |
84 | if(rlen != 0) | |
85 | error("dsa_key_from_blob: remaining bytes in key blob %d", rlen); | |
86 | buffer_free(&b); | |
87 | ||
88 | debug("keytype %s", ktype); | |
89 | #ifdef DEBUG_DSS | |
90 | DSA_print_fp(stderr, dsa, 8); | |
91 | #endif | |
92 | return key; | |
93 | } | |
94 | int | |
95 | dsa_make_key_blob(Key *key, unsigned char **blobp, unsigned int *lenp) | |
96 | { | |
97 | Buffer b; | |
98 | int len; | |
99 | unsigned char *buf; | |
100 | ||
101 | if (key == NULL || key->type != KEY_DSA) | |
102 | return 0; | |
103 | buffer_init(&b); | |
104 | buffer_put_cstring(&b, KEX_DSS); | |
105 | buffer_put_bignum2(&b, key->dsa->p); | |
106 | buffer_put_bignum2(&b, key->dsa->q); | |
107 | buffer_put_bignum2(&b, key->dsa->g); | |
108 | buffer_put_bignum2(&b, key->dsa->pub_key); | |
109 | len = buffer_len(&b); | |
110 | buf = xmalloc(len); | |
111 | memcpy(buf, buffer_ptr(&b), len); | |
112 | memset(buffer_ptr(&b), 0, len); | |
113 | buffer_free(&b); | |
114 | if (lenp != NULL) | |
115 | *lenp = len; | |
116 | if (blobp != NULL) | |
117 | *blobp = buf; | |
118 | return len; | |
119 | } | |
120 | int | |
121 | dsa_sign( | |
122 | Key *key, | |
123 | unsigned char **sigp, int *lenp, | |
124 | unsigned char *data, int datalen) | |
125 | { | |
126 | unsigned char *digest; | |
127 | unsigned char *ret; | |
128 | DSA_SIG *sig; | |
129 | EVP_MD *evp_md = EVP_sha1(); | |
130 | EVP_MD_CTX md; | |
131 | unsigned int rlen; | |
132 | unsigned int slen; | |
133 | unsigned int len; | |
134 | unsigned char sigblob[SIGBLOB_LEN]; | |
135 | Buffer b; | |
136 | ||
137 | if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) { | |
138 | error("dsa_sign: no DSA key"); | |
139 | return -1; | |
140 | } | |
141 | digest = xmalloc(evp_md->md_size); | |
142 | EVP_DigestInit(&md, evp_md); | |
143 | EVP_DigestUpdate(&md, data, datalen); | |
144 | EVP_DigestFinal(&md, digest, NULL); | |
145 | ||
146 | sig = DSA_do_sign(digest, evp_md->md_size, key->dsa); | |
147 | if (sig == NULL) { | |
148 | fatal("dsa_sign: cannot sign"); | |
149 | } | |
150 | ||
151 | rlen = BN_num_bytes(sig->r); | |
152 | slen = BN_num_bytes(sig->s); | |
153 | if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) { | |
154 | error("bad sig size %d %d", rlen, slen); | |
155 | DSA_SIG_free(sig); | |
156 | return -1; | |
157 | } | |
158 | debug("sig size %d %d", rlen, slen); | |
159 | ||
160 | memset(sigblob, 0, SIGBLOB_LEN); | |
161 | BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen); | |
162 | BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen); | |
163 | DSA_SIG_free(sig); | |
164 | ||
165 | if (datafellows & SSH_BUG_SIGBLOB) { | |
166 | debug("datafellows"); | |
167 | ret = xmalloc(SIGBLOB_LEN); | |
168 | memcpy(ret, sigblob, SIGBLOB_LEN); | |
169 | if (lenp != NULL) | |
170 | *lenp = SIGBLOB_LEN; | |
171 | if (sigp != NULL) | |
172 | *sigp = ret; | |
173 | } else { | |
174 | /* ietf-drafts */ | |
175 | buffer_init(&b); | |
176 | buffer_put_cstring(&b, KEX_DSS); | |
177 | buffer_put_string(&b, sigblob, SIGBLOB_LEN); | |
178 | len = buffer_len(&b); | |
179 | ret = xmalloc(len); | |
180 | memcpy(ret, buffer_ptr(&b), len); | |
181 | buffer_free(&b); | |
182 | if (lenp != NULL) | |
183 | *lenp = len; | |
184 | if (sigp != NULL) | |
185 | *sigp = ret; | |
186 | } | |
187 | return 0; | |
188 | } | |
189 | int | |
190 | dsa_verify( | |
191 | Key *key, | |
192 | unsigned char *signature, int signaturelen, | |
193 | unsigned char *data, int datalen) | |
194 | { | |
195 | Buffer b; | |
196 | unsigned char *digest; | |
197 | DSA_SIG *sig; | |
198 | EVP_MD *evp_md = EVP_sha1(); | |
199 | EVP_MD_CTX md; | |
200 | char *ktype; | |
201 | unsigned char *sigblob; | |
202 | char *txt; | |
203 | unsigned int len; | |
204 | int rlen; | |
205 | int ret; | |
206 | ||
207 | if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) { | |
208 | error("dsa_verify: no DSA key"); | |
209 | return -1; | |
210 | } | |
211 | ||
212 | if (!(datafellows & SSH_BUG_SIGBLOB) && | |
213 | signaturelen == SIGBLOB_LEN) { | |
214 | datafellows |= ~SSH_BUG_SIGBLOB; | |
215 | log("autodetect SSH_BUG_SIGBLOB"); | |
216 | } else if ((datafellows & SSH_BUG_SIGBLOB) && | |
217 | signaturelen != SIGBLOB_LEN) { | |
218 | log("autoremove SSH_BUG_SIGBLOB"); | |
219 | datafellows &= ~SSH_BUG_SIGBLOB; | |
220 | } | |
221 | ||
222 | debug("len %d datafellows %d", signaturelen, datafellows); | |
223 | ||
224 | /* fetch signature */ | |
225 | if (datafellows & SSH_BUG_SIGBLOB) { | |
226 | sigblob = signature; | |
227 | len = signaturelen; | |
228 | } else { | |
229 | /* ietf-drafts */ | |
230 | buffer_init(&b); | |
231 | buffer_append(&b, (char *) signature, signaturelen); | |
232 | ktype = buffer_get_string(&b, NULL); | |
233 | sigblob = (unsigned char *)buffer_get_string(&b, &len); | |
234 | rlen = buffer_len(&b); | |
235 | if(rlen != 0) | |
236 | error("remaining bytes in signature %d", rlen); | |
237 | buffer_free(&b); | |
238 | } | |
239 | ||
240 | if (len != SIGBLOB_LEN) { | |
241 | fatal("bad sigbloblen %d != SIGBLOB_LEN", len); | |
242 | } | |
243 | ||
244 | /* parse signature */ | |
245 | sig = DSA_SIG_new(); | |
246 | sig->r = BN_new(); | |
247 | sig->s = BN_new(); | |
248 | BN_bin2bn(sigblob, INTBLOB_LEN, sig->r); | |
249 | BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s); | |
250 | ||
251 | if (!(datafellows & SSH_BUG_SIGBLOB)) { | |
252 | memset(sigblob, 0, len); | |
253 | xfree(sigblob); | |
254 | } | |
255 | ||
256 | /* sha1 the data */ | |
257 | digest = xmalloc(evp_md->md_size); | |
258 | EVP_DigestInit(&md, evp_md); | |
259 | EVP_DigestUpdate(&md, data, datalen); | |
260 | EVP_DigestFinal(&md, digest, NULL); | |
261 | ||
262 | ret = DSA_do_verify(digest, evp_md->md_size, sig, key->dsa); | |
263 | ||
264 | memset(digest, 0, evp_md->md_size); | |
265 | xfree(digest); | |
266 | DSA_SIG_free(sig); | |
267 | ||
268 | switch (ret) { | |
269 | case 1: | |
270 | txt = "correct"; | |
271 | break; | |
272 | case 0: | |
273 | txt = "incorrect"; | |
274 | break; | |
275 | case -1: | |
276 | default: | |
277 | txt = "error"; | |
278 | break; | |
279 | } | |
280 | debug("dsa_verify: signature %s", txt); | |
281 | return ret; | |
282 | } | |
283 | ||
284 | Key * | |
285 | dsa_generate_key(unsigned int bits) | |
286 | { | |
287 | DSA *dsa = DSA_generate_parameters(bits, NULL, 0, NULL, NULL, NULL, NULL); | |
288 | Key *k; | |
289 | if (dsa == NULL) { | |
290 | fatal("DSA_generate_parameters failed"); | |
291 | } | |
292 | if (!DSA_generate_key(dsa)) { | |
293 | fatal("DSA_generate_keys failed"); | |
294 | } | |
295 | ||
296 | k = key_new(KEY_EMPTY); | |
297 | k->type = KEY_DSA; | |
298 | k->dsa = dsa; | |
299 | return k; | |
300 | } |