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552cc11b MW |
1 | /* |
2 | * Copyright (C) 2005-2008 Martin Willi | |
3 | * Copyright (C) 2005 Jan Hutter | |
4 | * Hochschule fuer Technik Rapperswil | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify it | |
7 | * under the terms of the GNU General Public License as published by the | |
8 | * Free Software Foundation; either version 2 of the License, or (at your | |
9 | * option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>. | |
10 | * | |
11 | * This program is distributed in the hope that it will be useful, but | |
12 | * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY | |
13 | * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
14 | * for more details. | |
15 | * | |
16 | * $Id$ | |
17 | */ | |
18 | ||
19 | #include <gmp.h> | |
20 | #include <sys/stat.h> | |
21 | #include <unistd.h> | |
22 | #include <stdio.h> | |
23 | #include <string.h> | |
24 | ||
25 | #include "gmp_rsa_public_key.h" | |
26 | ||
27 | #include <debug.h> | |
28 | #include <crypto/hashers/hasher.h> | |
29 | #include <asn1/asn1.h> | |
30 | #include <asn1/pem.h> | |
31 | ||
32 | /** | |
33 | * defined in gmp_rsa_private_key.c | |
34 | */ | |
35 | extern chunk_t gmp_mpz_to_asn1(const mpz_t value); | |
36 | ||
552cc11b MW |
37 | |
38 | /* ASN.1 definition of RSApublicKey */ | |
39 | static const asn1Object_t pubkeyObjects[] = { | |
40 | { 0, "RSAPublicKey", ASN1_SEQUENCE, ASN1_OBJ }, /* 0 */ | |
41 | { 1, "modulus", ASN1_INTEGER, ASN1_BODY }, /* 1 */ | |
42 | { 1, "publicExponent", ASN1_INTEGER, ASN1_BODY }, /* 2 */ | |
43 | }; | |
44 | ||
0ea70ca6 | 45 | #define PUB_KEY_RSA_PUBLIC_KEY 0 |
552cc11b MW |
46 | #define PUB_KEY_MODULUS 1 |
47 | #define PUB_KEY_EXPONENT 2 | |
48 | #define PUB_KEY_ROOF 3 | |
49 | ||
50 | /* ASN.1 definition of digestInfo */ | |
51 | static const asn1Object_t digestInfoObjects[] = { | |
52 | { 0, "digestInfo", ASN1_SEQUENCE, ASN1_OBJ }, /* 0 */ | |
53 | { 1, "digestAlgorithm", ASN1_EOC, ASN1_RAW }, /* 1 */ | |
54 | { 1, "digest", ASN1_OCTET_STRING, ASN1_BODY }, /* 2 */ | |
55 | }; | |
56 | ||
57 | #define DIGEST_INFO 0 | |
58 | #define DIGEST_INFO_ALGORITHM 1 | |
59 | #define DIGEST_INFO_DIGEST 2 | |
60 | #define DIGEST_INFO_ROOF 3 | |
61 | ||
62 | typedef struct private_gmp_rsa_public_key_t private_gmp_rsa_public_key_t; | |
63 | ||
64 | /** | |
65 | * Private data structure with signing context. | |
66 | */ | |
67 | struct private_gmp_rsa_public_key_t { | |
68 | /** | |
69 | * Public interface for this signer. | |
70 | */ | |
71 | gmp_rsa_public_key_t public; | |
72 | ||
73 | /** | |
74 | * Public modulus. | |
75 | */ | |
76 | mpz_t n; | |
77 | ||
78 | /** | |
79 | * Public exponent. | |
80 | */ | |
81 | mpz_t e; | |
82 | ||
83 | /** | |
84 | * Keysize in bytes. | |
85 | */ | |
86 | size_t k; | |
87 | ||
88 | /** | |
89 | * Keyid formed as a SHA-1 hash of a publicKeyInfo object | |
90 | */ | |
91 | identification_t *keyid_info; | |
92 | ||
93 | /** | |
94 | * Keyid formed as a SHA-1 hash of a publicKey object | |
95 | */ | |
96 | identification_t *keyid; | |
97 | ||
98 | /** | |
99 | * reference counter | |
100 | */ | |
101 | refcount_t ref; | |
102 | }; | |
103 | ||
104 | /** | |
105 | * RSAEP algorithm specified in PKCS#1. | |
106 | */ | |
107 | static chunk_t rsaep(private_gmp_rsa_public_key_t *this, chunk_t data) | |
108 | { | |
109 | mpz_t m, c; | |
110 | chunk_t encrypted; | |
111 | ||
112 | mpz_init(c); | |
113 | mpz_init(m); | |
114 | ||
115 | mpz_import(m, data.len, 1, 1, 1, 0, data.ptr); | |
116 | ||
117 | mpz_powm(c, m, this->e, this->n); | |
118 | ||
119 | encrypted.len = this->k; | |
120 | encrypted.ptr = mpz_export(NULL, NULL, 1, encrypted.len, 1, 0, c); | |
121 | ||
122 | mpz_clear(c); | |
123 | mpz_clear(m); | |
124 | ||
125 | return encrypted; | |
126 | } | |
127 | ||
128 | /** | |
129 | * RSAVP1 algorithm specified in PKCS#1. | |
130 | */ | |
131 | static chunk_t rsavp1(private_gmp_rsa_public_key_t *this, chunk_t data) | |
132 | { | |
133 | return rsaep(this, data); | |
134 | } | |
135 | ||
136 | /** | |
137 | * Verification of an EMPSA PKCS1 signature described in PKCS#1 | |
138 | */ | |
139 | static bool verify_emsa_pkcs1_signature(private_gmp_rsa_public_key_t *this, | |
140 | hash_algorithm_t algorithm, | |
141 | chunk_t data, chunk_t signature) | |
142 | { | |
143 | chunk_t em_ori, em; | |
144 | bool res = FALSE; | |
145 | ||
146 | /* remove any preceding 0-bytes from signature */ | |
147 | while (signature.len && *(signature.ptr) == 0x00) | |
148 | { | |
149 | signature.len -= 1; | |
150 | signature.ptr++; | |
151 | } | |
152 | ||
153 | if (signature.len > this->k) | |
154 | { | |
155 | return INVALID_ARG; | |
156 | } | |
157 | ||
158 | /* unpack signature */ | |
159 | em_ori = em = rsavp1(this, signature); | |
160 | ||
161 | /* result should look like this: | |
162 | * EM = 0x00 || 0x01 || PS || 0x00 || T. | |
163 | * PS = 0xFF padding, with length to fill em | |
164 | * T = oid || hash | |
165 | */ | |
166 | ||
167 | /* check magic bytes */ | |
168 | if (*(em.ptr) != 0x00 || *(em.ptr+1) != 0x01) | |
169 | { | |
170 | goto end; | |
171 | } | |
172 | em.ptr += 2; | |
173 | em.len -= 2; | |
174 | ||
175 | /* find magic 0x00 */ | |
176 | while (em.len > 0) | |
177 | { | |
178 | if (*em.ptr == 0x00) | |
179 | { | |
180 | /* found magic byte, stop */ | |
181 | em.ptr++; | |
182 | em.len--; | |
183 | break; | |
184 | } | |
185 | else if (*em.ptr != 0xFF) | |
186 | { | |
187 | /* bad padding, decryption failed ?!*/ | |
188 | goto end; | |
189 | } | |
190 | em.ptr++; | |
191 | em.len--; | |
192 | } | |
193 | ||
194 | if (em.len == 0) | |
195 | { | |
196 | /* no digestInfo found */ | |
197 | goto end; | |
198 | } | |
199 | ||
200 | /* parse ASN.1-based digestInfo */ | |
201 | { | |
202 | asn1_ctx_t ctx; | |
203 | chunk_t object; | |
204 | u_int level; | |
205 | int objectID = 0; | |
206 | hash_algorithm_t hash_algorithm = HASH_UNKNOWN; | |
207 | ||
208 | asn1_init(&ctx, em, 0, FALSE, FALSE); | |
209 | ||
210 | while (objectID < DIGEST_INFO_ROOF) | |
211 | { | |
212 | if (!extract_object(digestInfoObjects, &objectID, &object, &level, &ctx)) | |
213 | { | |
214 | goto end; | |
215 | } | |
216 | switch (objectID) | |
217 | { | |
218 | case DIGEST_INFO: | |
219 | { | |
220 | if (em.len > object.len) | |
221 | { | |
222 | DBG1("digestInfo field in signature is followed by %u surplus bytes", | |
223 | em.len - object.len); | |
224 | goto end; | |
225 | } | |
226 | break; | |
227 | } | |
228 | case DIGEST_INFO_ALGORITHM: | |
229 | { | |
230 | int hash_oid = parse_algorithmIdentifier(object, level+1, NULL); | |
231 | ||
232 | hash_algorithm = hasher_algorithm_from_oid(hash_oid); | |
233 | if (hash_algorithm == HASH_UNKNOWN || | |
234 | (algorithm != HASH_UNKNOWN && hash_algorithm != algorithm)) | |
235 | { | |
236 | DBG1("wrong hash algorithm used in signature"); | |
237 | goto end; | |
238 | } | |
239 | break; | |
240 | } | |
241 | case DIGEST_INFO_DIGEST: | |
242 | { | |
243 | chunk_t hash; | |
244 | hasher_t *hasher; | |
245 | ||
246 | hasher = lib->crypto->create_hasher(lib->crypto, hash_algorithm); | |
247 | if (hasher == NULL) | |
248 | { | |
249 | DBG1("hash algorithm %N not supported", | |
250 | hash_algorithm_names, hash_algorithm); | |
251 | goto end; | |
252 | } | |
253 | ||
254 | if (object.len != hasher->get_hash_size(hasher)) | |
255 | { | |
256 | DBG1("hash size in signature is %u bytes instead of %u " | |
257 | "bytes", object.len, hasher->get_hash_size(hasher)); | |
258 | hasher->destroy(hasher); | |
259 | goto end; | |
260 | } | |
261 | ||
262 | /* build our own hash and compare */ | |
263 | hasher->allocate_hash(hasher, data, &hash); | |
264 | hasher->destroy(hasher); | |
265 | res = memeq(object.ptr, hash.ptr, hash.len); | |
266 | free(hash.ptr); | |
267 | break; | |
268 | } | |
269 | default: | |
270 | break; | |
271 | } | |
272 | objectID++; | |
273 | } | |
274 | } | |
275 | ||
276 | end: | |
277 | free(em_ori.ptr); | |
278 | return res; | |
279 | } | |
280 | ||
281 | /** | |
282 | * Implementation of public_key_t.get_type. | |
283 | */ | |
284 | static key_type_t get_type(private_gmp_rsa_public_key_t *this) | |
285 | { | |
286 | return KEY_RSA; | |
287 | } | |
288 | ||
289 | /** | |
290 | * Implementation of public_key_t.verify. | |
291 | */ | |
292 | static bool verify(private_gmp_rsa_public_key_t *this, signature_scheme_t scheme, | |
293 | chunk_t data, chunk_t signature) | |
294 | { | |
295 | switch (scheme) | |
296 | { | |
297 | case SIGN_DEFAULT: /* default is EMSA-PKCS1 using included OID */ | |
298 | return verify_emsa_pkcs1_signature(this, HASH_UNKNOWN, data, signature); | |
299 | case SIGN_RSA_EMSA_PKCS1_MD5: | |
300 | return verify_emsa_pkcs1_signature(this, HASH_MD5, data, signature); | |
301 | case SIGN_RSA_EMSA_PKCS1_SHA1: | |
302 | return verify_emsa_pkcs1_signature(this, HASH_SHA1, data, signature); | |
303 | case SIGN_RSA_EMSA_PKCS1_SHA256: | |
304 | return verify_emsa_pkcs1_signature(this, HASH_SHA256, data, signature); | |
305 | case SIGN_RSA_EMSA_PKCS1_SHA384: | |
306 | return verify_emsa_pkcs1_signature(this, HASH_SHA384, data, signature); | |
307 | case SIGN_RSA_EMSA_PKCS1_SHA512: | |
308 | return verify_emsa_pkcs1_signature(this, HASH_SHA512, data, signature); | |
309 | default: | |
310 | DBG1("signature scheme %N not supported in RSA", | |
311 | signature_scheme_names, scheme); | |
312 | return FALSE; | |
313 | } | |
314 | } | |
315 | ||
316 | /** | |
317 | * Implementation of public_key_t.get_keysize. | |
318 | */ | |
319 | static bool encrypt(private_gmp_rsa_public_key_t *this, chunk_t crypto, chunk_t *plain) | |
320 | { | |
321 | DBG1("RSA public key encryption not implemented"); | |
322 | return FALSE; | |
323 | } | |
324 | ||
325 | /** | |
326 | * Implementation of public_key_t.get_keysize. | |
327 | */ | |
328 | static size_t get_keysize(private_gmp_rsa_public_key_t *this) | |
329 | { | |
330 | return this->k; | |
331 | } | |
332 | ||
333 | /** | |
334 | * Implementation of public_key_t.get_id. | |
335 | */ | |
336 | static identification_t *get_id(private_gmp_rsa_public_key_t *this, | |
337 | id_type_t type) | |
338 | { | |
339 | switch (type) | |
340 | { | |
341 | case ID_PUBKEY_INFO_SHA1: | |
342 | return this->keyid_info; | |
343 | case ID_PUBKEY_SHA1: | |
344 | return this->keyid; | |
345 | default: | |
346 | return NULL; | |
347 | } | |
348 | } | |
349 | ||
350 | /* | |
351 | * Implementation of public_key_t.get_encoding. | |
352 | */ | |
353 | static chunk_t get_encoding(private_gmp_rsa_public_key_t *this) | |
354 | { | |
355 | return asn1_wrap(ASN1_SEQUENCE, "mm", | |
356 | gmp_mpz_to_asn1(this->n), | |
357 | gmp_mpz_to_asn1(this->e)); | |
358 | } | |
359 | ||
360 | /** | |
361 | * Implementation of public_key_t.get_ref. | |
362 | */ | |
363 | static private_gmp_rsa_public_key_t* get_ref(private_gmp_rsa_public_key_t *this) | |
364 | { | |
365 | ref_get(&this->ref); | |
366 | return this; | |
367 | } | |
368 | ||
369 | /** | |
370 | * Implementation of gmp_rsa_public_key.destroy. | |
371 | */ | |
372 | static void destroy(private_gmp_rsa_public_key_t *this) | |
373 | { | |
374 | if (ref_put(&this->ref)) | |
375 | { | |
376 | mpz_clear(this->n); | |
377 | mpz_clear(this->e); | |
378 | DESTROY_IF(this->keyid); | |
379 | DESTROY_IF(this->keyid_info); | |
380 | free(this); | |
381 | } | |
382 | } | |
383 | ||
384 | /** | |
385 | * Generic private constructor | |
386 | */ | |
387 | static private_gmp_rsa_public_key_t *gmp_rsa_public_key_create_empty() | |
388 | { | |
389 | private_gmp_rsa_public_key_t *this = malloc_thing(private_gmp_rsa_public_key_t); | |
390 | ||
391 | this->public.interface.get_type = (key_type_t (*)(public_key_t *this))get_type; | |
392 | this->public.interface.verify = (bool (*)(public_key_t *this, signature_scheme_t scheme, chunk_t data, chunk_t signature))verify; | |
393 | this->public.interface.encrypt = (bool (*)(public_key_t *this, chunk_t crypto, chunk_t *plain))encrypt; | |
394 | this->public.interface.get_keysize = (size_t (*) (public_key_t *this))get_keysize; | |
395 | this->public.interface.get_id = (identification_t* (*) (public_key_t *this,id_type_t))get_id; | |
396 | this->public.interface.get_encoding = (chunk_t(*)(public_key_t*))get_encoding; | |
397 | this->public.interface.get_ref = (public_key_t* (*)(public_key_t *this))get_ref; | |
398 | this->public.interface.destroy = (void (*)(public_key_t *this))destroy; | |
399 | ||
400 | this->keyid = NULL; | |
401 | this->keyid_info = NULL; | |
402 | this->ref = 1; | |
403 | ||
404 | return this; | |
405 | } | |
406 | ||
407 | /** | |
408 | * Build the RSA key identifier from n and e using SHA1 hashed publicKey(Info). | |
409 | * Also used in rsa_private_key.c. | |
410 | */ | |
411 | bool gmp_rsa_public_key_build_id(mpz_t n, mpz_t e, identification_t **keyid, | |
412 | identification_t **keyid_info) | |
413 | { | |
414 | chunk_t publicKeyInfo, publicKey, hash; | |
415 | hasher_t *hasher; | |
416 | ||
417 | hasher = lib->crypto->create_hasher(lib->crypto, HASH_SHA1); | |
418 | if (hasher == NULL) | |
419 | { | |
420 | DBG1("SHA1 hash algorithm not supported, unable to use RSA"); | |
421 | return FALSE; | |
422 | } | |
423 | publicKey = asn1_wrap(ASN1_SEQUENCE, "mm", | |
424 | gmp_mpz_to_asn1(n), | |
425 | gmp_mpz_to_asn1(e)); | |
426 | hasher->allocate_hash(hasher, publicKey, &hash); | |
427 | *keyid = identification_create_from_encoding(ID_PUBKEY_SHA1, hash); | |
428 | chunk_free(&hash); | |
429 | ||
430 | publicKeyInfo = asn1_wrap(ASN1_SEQUENCE, "cm", | |
431 | asn1_algorithmIdentifier(OID_RSA_ENCRYPTION), | |
432 | asn1_bitstring("m", publicKey)); | |
433 | hasher->allocate_hash(hasher, publicKeyInfo, &hash); | |
434 | *keyid_info = identification_create_from_encoding(ID_PUBKEY_INFO_SHA1, hash); | |
435 | chunk_free(&hash); | |
436 | ||
437 | hasher->destroy(hasher); | |
438 | chunk_free(&publicKeyInfo); | |
439 | ||
440 | return TRUE; | |
441 | } | |
442 | ||
d7c529f5 MW |
443 | /** |
444 | * Create a public key from mpz values, used in gmp_rsa_private_key | |
445 | */ | |
446 | gmp_rsa_public_key_t *gmp_rsa_public_key_create_from_n_e(mpz_t n, mpz_t e) | |
447 | { | |
448 | private_gmp_rsa_public_key_t *this = gmp_rsa_public_key_create_empty(); | |
449 | ||
450 | mpz_init_set(this->n, n); | |
451 | mpz_init_set(this->e, e); | |
452 | ||
453 | this->k = (mpz_sizeinbase(this->n, 2) + 7) / 8; | |
454 | if (!gmp_rsa_public_key_build_id(this->n, this->e, | |
455 | &this->keyid, &this->keyid_info)) | |
456 | { | |
457 | destroy(this); | |
458 | return NULL; | |
459 | } | |
460 | return &this->public; | |
461 | } | |
462 | ||
552cc11b MW |
463 | /** |
464 | * Load a public key from an ASN1 encoded blob | |
465 | */ | |
466 | static gmp_rsa_public_key_t *load(chunk_t blob) | |
467 | { | |
468 | asn1_ctx_t ctx; | |
469 | chunk_t object; | |
470 | u_int level; | |
471 | int objectID = 0; | |
472 | private_gmp_rsa_public_key_t *this = gmp_rsa_public_key_create_empty(); | |
473 | ||
474 | mpz_init(this->n); | |
475 | mpz_init(this->e); | |
476 | ||
477 | asn1_init(&ctx, blob, 0, FALSE, FALSE); | |
478 | ||
479 | while (objectID < PUB_KEY_ROOF) | |
480 | { | |
481 | if (!extract_object(pubkeyObjects, &objectID, &object, &level, &ctx)) | |
482 | { | |
483 | free(blob.ptr); | |
484 | destroy(this); | |
485 | return NULL; | |
486 | } | |
487 | switch (objectID) | |
488 | { | |
489 | case PUB_KEY_MODULUS: | |
490 | mpz_import(this->n, object.len, 1, 1, 1, 0, object.ptr); | |
491 | break; | |
492 | case PUB_KEY_EXPONENT: | |
493 | mpz_import(this->e, object.len, 1, 1, 1, 0, object.ptr); | |
494 | break; | |
495 | } | |
496 | objectID++; | |
497 | } | |
498 | free(blob.ptr); | |
499 | this->k = (mpz_sizeinbase(this->n, 2) + 7) / 8; | |
500 | if (!gmp_rsa_public_key_build_id(this->n, this->e, | |
501 | &this->keyid, &this->keyid_info)) | |
502 | { | |
503 | destroy(this); | |
504 | return NULL; | |
505 | } | |
506 | return &this->public; | |
507 | } | |
508 | ||
552cc11b MW |
509 | typedef struct private_builder_t private_builder_t; |
510 | /** | |
511 | * Builder implementation for key loading | |
512 | */ | |
513 | struct private_builder_t { | |
514 | /** implements the builder interface */ | |
515 | builder_t public; | |
516 | /** loaded public key */ | |
517 | gmp_rsa_public_key_t *key; | |
518 | }; | |
519 | ||
520 | /** | |
521 | * Implementation of builder_t.build | |
522 | */ | |
523 | static gmp_rsa_public_key_t *build(private_builder_t *this) | |
524 | { | |
525 | gmp_rsa_public_key_t *key = this->key; | |
526 | ||
527 | free(this); | |
528 | return key; | |
529 | } | |
530 | ||
531 | /** | |
532 | * Implementation of builder_t.add | |
533 | */ | |
534 | static void add(private_builder_t *this, builder_part_t part, ...) | |
535 | { | |
536 | va_list args; | |
537 | ||
538 | if (this->key) | |
539 | { | |
540 | DBG1("ignoring surplus build part %N", builder_part_names, part); | |
541 | return; | |
542 | } | |
543 | ||
544 | switch (part) | |
545 | { | |
546 | case BUILD_BLOB_ASN1_DER: | |
547 | { | |
548 | va_start(args, part); | |
549 | this->key = load(va_arg(args, chunk_t)); | |
550 | va_end(args); | |
551 | break; | |
552 | } | |
553 | default: | |
554 | DBG1("ignoring unsupported build part %N", builder_part_names, part); | |
555 | break; | |
556 | } | |
557 | } | |
558 | ||
559 | /** | |
560 | * Builder construction function | |
561 | */ | |
562 | builder_t *gmp_rsa_public_key_builder(key_type_t type) | |
563 | { | |
564 | private_builder_t *this; | |
565 | ||
566 | if (type != KEY_RSA) | |
567 | { | |
568 | return NULL; | |
569 | } | |
570 | ||
571 | this = malloc_thing(private_builder_t); | |
572 | ||
573 | this->key = NULL; | |
574 | this->public.add = (void(*)(builder_t *this, builder_part_t part, ...))add; | |
575 | this->public.build = (void*(*)(builder_t *this))build; | |
576 | ||
577 | return &this->public; | |
578 | } | |
579 |