1 /*
2 * The RSA public-key cryptosystem
3 *
4 * Copyright The Mbed TLS Contributors
5 * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
6 */
7
8 /*
9 * The following sources were referenced in the design of this implementation
10 * of the RSA algorithm:
11 *
12 * [1] A method for obtaining digital signatures and public-key cryptosystems
13 * R Rivest, A Shamir, and L Adleman
14 * http://people.csail.mit.edu/rivest/pubs.html#RSA78
15 *
16 * [2] Handbook of Applied Cryptography - 1997, Chapter 8
17 * Menezes, van Oorschot and Vanstone
18 *
19 * [3] Malware Guard Extension: Using SGX to Conceal Cache Attacks
20 * Michael Schwarz, Samuel Weiser, Daniel Gruss, Clémentine Maurice and
21 * Stefan Mangard
22 * https://arxiv.org/abs/1702.08719v2
23 *
24 */
25
26 #include "common.h"
27
28 #if defined(MBEDTLS_RSA_C)
29
30 #include "mbedtls/rsa.h"
31 #include "bignum_core.h"
32 #include "rsa_alt_helpers.h"
33 #include "rsa_internal.h"
34 #include "mbedtls/oid.h"
35 #include "mbedtls/asn1write.h"
36 #include "mbedtls/platform_util.h"
37 #include "mbedtls/error.h"
38 #include "constant_time_internal.h"
39 #include "mbedtls/constant_time.h"
40 #include "md_psa.h"
41
42 #include <string.h>
43
44 #if defined(MBEDTLS_PKCS1_V15) && !defined(__OpenBSD__) && !defined(__NetBSD__)
45 #include <stdlib.h>
46 #endif
47
48 #include "mbedtls/platform.h"
49
50 /*
51 * Wrapper around mbedtls_asn1_get_mpi() that rejects zero.
52 *
53 * The value zero is:
54 * - never a valid value for an RSA parameter
55 * - interpreted as "omitted, please reconstruct" by mbedtls_rsa_complete().
56 *
57 * Since values can't be omitted in PKCS#1, passing a zero value to
58 * rsa_complete() would be incorrect, so reject zero values early.
59 */
asn1_get_nonzero_mpi(unsigned char ** p,const unsigned char * end,mbedtls_mpi * X)60 static int asn1_get_nonzero_mpi(unsigned char **p,
61 const unsigned char *end,
62 mbedtls_mpi *X)
63 {
64 int ret;
65
66 ret = mbedtls_asn1_get_mpi(p, end, X);
67 if (ret != 0) {
68 return ret;
69 }
70
71 if (mbedtls_mpi_cmp_int(X, 0) == 0) {
72 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
73 }
74
75 return 0;
76 }
77
mbedtls_rsa_parse_key(mbedtls_rsa_context * rsa,const unsigned char * key,size_t keylen)78 int mbedtls_rsa_parse_key(mbedtls_rsa_context *rsa, const unsigned char *key, size_t keylen)
79 {
80 int ret, version;
81 size_t len;
82 unsigned char *p, *end;
83
84 mbedtls_mpi T;
85 mbedtls_mpi_init(&T);
86
87 p = (unsigned char *) key;
88 end = p + keylen;
89
90 /*
91 * This function parses the RSAPrivateKey (PKCS#1)
92 *
93 * RSAPrivateKey ::= SEQUENCE {
94 * version Version,
95 * modulus INTEGER, -- n
96 * publicExponent INTEGER, -- e
97 * privateExponent INTEGER, -- d
98 * prime1 INTEGER, -- p
99 * prime2 INTEGER, -- q
100 * exponent1 INTEGER, -- d mod (p-1)
101 * exponent2 INTEGER, -- d mod (q-1)
102 * coefficient INTEGER, -- (inverse of q) mod p
103 * otherPrimeInfos OtherPrimeInfos OPTIONAL
104 * }
105 */
106 if ((ret = mbedtls_asn1_get_tag(&p, end, &len,
107 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE)) != 0) {
108 return ret;
109 }
110
111 if (end != p + len) {
112 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
113 }
114
115 if ((ret = mbedtls_asn1_get_int(&p, end, &version)) != 0) {
116 return ret;
117 }
118
119 if (version != 0) {
120 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
121 }
122
123 /* Import N */
124 if ((ret = asn1_get_nonzero_mpi(&p, end, &T)) != 0 ||
125 (ret = mbedtls_rsa_import(rsa, &T, NULL, NULL,
126 NULL, NULL)) != 0) {
127 goto cleanup;
128 }
129
130 /* Import E */
131 if ((ret = asn1_get_nonzero_mpi(&p, end, &T)) != 0 ||
132 (ret = mbedtls_rsa_import(rsa, NULL, NULL, NULL,
133 NULL, &T)) != 0) {
134 goto cleanup;
135 }
136
137 /* Import D */
138 if ((ret = asn1_get_nonzero_mpi(&p, end, &T)) != 0 ||
139 (ret = mbedtls_rsa_import(rsa, NULL, NULL, NULL,
140 &T, NULL)) != 0) {
141 goto cleanup;
142 }
143
144 /* Import P */
145 if ((ret = asn1_get_nonzero_mpi(&p, end, &T)) != 0 ||
146 (ret = mbedtls_rsa_import(rsa, NULL, &T, NULL,
147 NULL, NULL)) != 0) {
148 goto cleanup;
149 }
150
151 /* Import Q */
152 if ((ret = asn1_get_nonzero_mpi(&p, end, &T)) != 0 ||
153 (ret = mbedtls_rsa_import(rsa, NULL, NULL, &T,
154 NULL, NULL)) != 0) {
155 goto cleanup;
156 }
157
158 #if !defined(MBEDTLS_RSA_NO_CRT) && !defined(MBEDTLS_RSA_ALT)
159 /*
160 * The RSA CRT parameters DP, DQ and QP are nominally redundant, in
161 * that they can be easily recomputed from D, P and Q. However by
162 * parsing them from the PKCS1 structure it is possible to avoid
163 * recalculating them which both reduces the overhead of loading
164 * RSA private keys into memory and also avoids side channels which
165 * can arise when computing those values, since all of D, P, and Q
166 * are secret. See https://eprint.iacr.org/2020/055 for a
167 * description of one such attack.
168 */
169
170 /* Import DP */
171 if ((ret = asn1_get_nonzero_mpi(&p, end, &T)) != 0 ||
172 (ret = mbedtls_mpi_copy(&rsa->DP, &T)) != 0) {
173 goto cleanup;
174 }
175
176 /* Import DQ */
177 if ((ret = asn1_get_nonzero_mpi(&p, end, &T)) != 0 ||
178 (ret = mbedtls_mpi_copy(&rsa->DQ, &T)) != 0) {
179 goto cleanup;
180 }
181
182 /* Import QP */
183 if ((ret = asn1_get_nonzero_mpi(&p, end, &T)) != 0 ||
184 (ret = mbedtls_mpi_copy(&rsa->QP, &T)) != 0) {
185 goto cleanup;
186 }
187
188 #else
189 /* Verify existence of the CRT params */
190 if ((ret = asn1_get_nonzero_mpi(&p, end, &T)) != 0 ||
191 (ret = asn1_get_nonzero_mpi(&p, end, &T)) != 0 ||
192 (ret = asn1_get_nonzero_mpi(&p, end, &T)) != 0) {
193 goto cleanup;
194 }
195 #endif
196
197 /* rsa_complete() doesn't complete anything with the default
198 * implementation but is still called:
199 * - for the benefit of alternative implementation that may want to
200 * pre-compute stuff beyond what's provided (eg Montgomery factors)
201 * - as is also sanity-checks the key
202 *
203 * Furthermore, we also check the public part for consistency with
204 * mbedtls_pk_parse_pubkey(), as it includes size minima for example.
205 */
206 if ((ret = mbedtls_rsa_complete(rsa)) != 0 ||
207 (ret = mbedtls_rsa_check_pubkey(rsa)) != 0) {
208 goto cleanup;
209 }
210
211 if (p != end) {
212 ret = MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
213 }
214
215 cleanup:
216
217 mbedtls_mpi_free(&T);
218
219 if (ret != 0) {
220 mbedtls_rsa_free(rsa);
221 }
222
223 return ret;
224 }
225
mbedtls_rsa_parse_pubkey(mbedtls_rsa_context * rsa,const unsigned char * key,size_t keylen)226 int mbedtls_rsa_parse_pubkey(mbedtls_rsa_context *rsa, const unsigned char *key, size_t keylen)
227 {
228 unsigned char *p = (unsigned char *) key;
229 unsigned char *end = (unsigned char *) (key + keylen);
230 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
231 size_t len;
232
233 /*
234 * RSAPublicKey ::= SEQUENCE {
235 * modulus INTEGER, -- n
236 * publicExponent INTEGER -- e
237 * }
238 */
239
240 if ((ret = mbedtls_asn1_get_tag(&p, end, &len,
241 MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE)) != 0) {
242 return ret;
243 }
244
245 if (end != p + len) {
246 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
247 }
248
249 /* Import N */
250 if ((ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_INTEGER)) != 0) {
251 return ret;
252 }
253
254 if ((ret = mbedtls_rsa_import_raw(rsa, p, len, NULL, 0, NULL, 0,
255 NULL, 0, NULL, 0)) != 0) {
256 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
257 }
258
259 p += len;
260
261 /* Import E */
262 if ((ret = mbedtls_asn1_get_tag(&p, end, &len, MBEDTLS_ASN1_INTEGER)) != 0) {
263 return ret;
264 }
265
266 if ((ret = mbedtls_rsa_import_raw(rsa, NULL, 0, NULL, 0, NULL, 0,
267 NULL, 0, p, len)) != 0) {
268 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
269 }
270
271 p += len;
272
273 if (mbedtls_rsa_complete(rsa) != 0 ||
274 mbedtls_rsa_check_pubkey(rsa) != 0) {
275 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
276 }
277
278 if (p != end) {
279 return MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
280 }
281
282 return 0;
283 }
284
mbedtls_rsa_write_key(const mbedtls_rsa_context * rsa,unsigned char * start,unsigned char ** p)285 int mbedtls_rsa_write_key(const mbedtls_rsa_context *rsa, unsigned char *start,
286 unsigned char **p)
287 {
288 size_t len = 0;
289 int ret;
290
291 mbedtls_mpi T; /* Temporary holding the exported parameters */
292
293 /*
294 * Export the parameters one after another to avoid simultaneous copies.
295 */
296
297 mbedtls_mpi_init(&T);
298
299 /* Export QP */
300 if ((ret = mbedtls_rsa_export_crt(rsa, NULL, NULL, &T)) != 0 ||
301 (ret = mbedtls_asn1_write_mpi(p, start, &T)) < 0) {
302 goto end_of_export;
303 }
304 len += ret;
305
306 /* Export DQ */
307 if ((ret = mbedtls_rsa_export_crt(rsa, NULL, &T, NULL)) != 0 ||
308 (ret = mbedtls_asn1_write_mpi(p, start, &T)) < 0) {
309 goto end_of_export;
310 }
311 len += ret;
312
313 /* Export DP */
314 if ((ret = mbedtls_rsa_export_crt(rsa, &T, NULL, NULL)) != 0 ||
315 (ret = mbedtls_asn1_write_mpi(p, start, &T)) < 0) {
316 goto end_of_export;
317 }
318 len += ret;
319
320 /* Export Q */
321 if ((ret = mbedtls_rsa_export(rsa, NULL, NULL, &T, NULL, NULL)) != 0 ||
322 (ret = mbedtls_asn1_write_mpi(p, start, &T)) < 0) {
323 goto end_of_export;
324 }
325 len += ret;
326
327 /* Export P */
328 if ((ret = mbedtls_rsa_export(rsa, NULL, &T, NULL, NULL, NULL)) != 0 ||
329 (ret = mbedtls_asn1_write_mpi(p, start, &T)) < 0) {
330 goto end_of_export;
331 }
332 len += ret;
333
334 /* Export D */
335 if ((ret = mbedtls_rsa_export(rsa, NULL, NULL, NULL, &T, NULL)) != 0 ||
336 (ret = mbedtls_asn1_write_mpi(p, start, &T)) < 0) {
337 goto end_of_export;
338 }
339 len += ret;
340
341 /* Export E */
342 if ((ret = mbedtls_rsa_export(rsa, NULL, NULL, NULL, NULL, &T)) != 0 ||
343 (ret = mbedtls_asn1_write_mpi(p, start, &T)) < 0) {
344 goto end_of_export;
345 }
346 len += ret;
347
348 /* Export N */
349 if ((ret = mbedtls_rsa_export(rsa, &T, NULL, NULL, NULL, NULL)) != 0 ||
350 (ret = mbedtls_asn1_write_mpi(p, start, &T)) < 0) {
351 goto end_of_export;
352 }
353 len += ret;
354
355 end_of_export:
356
357 mbedtls_mpi_free(&T);
358 if (ret < 0) {
359 return ret;
360 }
361
362 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_int(p, start, 0));
363 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
364 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start,
365 MBEDTLS_ASN1_CONSTRUCTED |
366 MBEDTLS_ASN1_SEQUENCE));
367
368 return (int) len;
369 }
370
371 /*
372 * RSAPublicKey ::= SEQUENCE {
373 * modulus INTEGER, -- n
374 * publicExponent INTEGER -- e
375 * }
376 */
mbedtls_rsa_write_pubkey(const mbedtls_rsa_context * rsa,unsigned char * start,unsigned char ** p)377 int mbedtls_rsa_write_pubkey(const mbedtls_rsa_context *rsa, unsigned char *start,
378 unsigned char **p)
379 {
380 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
381 size_t len = 0;
382 mbedtls_mpi T;
383
384 mbedtls_mpi_init(&T);
385
386 /* Export E */
387 if ((ret = mbedtls_rsa_export(rsa, NULL, NULL, NULL, NULL, &T)) != 0 ||
388 (ret = mbedtls_asn1_write_mpi(p, start, &T)) < 0) {
389 goto end_of_export;
390 }
391 len += ret;
392
393 /* Export N */
394 if ((ret = mbedtls_rsa_export(rsa, &T, NULL, NULL, NULL, NULL)) != 0 ||
395 (ret = mbedtls_asn1_write_mpi(p, start, &T)) < 0) {
396 goto end_of_export;
397 }
398 len += ret;
399
400 end_of_export:
401
402 mbedtls_mpi_free(&T);
403 if (ret < 0) {
404 return ret;
405 }
406
407 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));
408 MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_CONSTRUCTED |
409 MBEDTLS_ASN1_SEQUENCE));
410
411 return (int) len;
412 }
413
414 #if defined(MBEDTLS_PKCS1_V15) && defined(MBEDTLS_RSA_C) && !defined(MBEDTLS_RSA_ALT)
415
416 /** This function performs the unpadding part of a PKCS#1 v1.5 decryption
417 * operation (EME-PKCS1-v1_5 decoding).
418 *
419 * \note The return value from this function is a sensitive value
420 * (this is unusual). #MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE shouldn't happen
421 * in a well-written application, but 0 vs #MBEDTLS_ERR_RSA_INVALID_PADDING
422 * is often a situation that an attacker can provoke and leaking which
423 * one is the result is precisely the information the attacker wants.
424 *
425 * \param input The input buffer which is the payload inside PKCS#1v1.5
426 * encryption padding, called the "encoded message EM"
427 * by the terminology.
428 * \param ilen The length of the payload in the \p input buffer.
429 * \param output The buffer for the payload, called "message M" by the
430 * PKCS#1 terminology. This must be a writable buffer of
431 * length \p output_max_len bytes.
432 * \param olen The address at which to store the length of
433 * the payload. This must not be \c NULL.
434 * \param output_max_len The length in bytes of the output buffer \p output.
435 *
436 * \return \c 0 on success.
437 * \return #MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE
438 * The output buffer is too small for the unpadded payload.
439 * \return #MBEDTLS_ERR_RSA_INVALID_PADDING
440 * The input doesn't contain properly formatted padding.
441 */
mbedtls_ct_rsaes_pkcs1_v15_unpadding(unsigned char * input,size_t ilen,unsigned char * output,size_t output_max_len,size_t * olen)442 static int mbedtls_ct_rsaes_pkcs1_v15_unpadding(unsigned char *input,
443 size_t ilen,
444 unsigned char *output,
445 size_t output_max_len,
446 size_t *olen)
447 {
448 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
449 size_t i, plaintext_max_size;
450
451 /* The following variables take sensitive values: their value must
452 * not leak into the observable behavior of the function other than
453 * the designated outputs (output, olen, return value). Otherwise
454 * this would open the execution of the function to
455 * side-channel-based variants of the Bleichenbacher padding oracle
456 * attack. Potential side channels include overall timing, memory
457 * access patterns (especially visible to an adversary who has access
458 * to a shared memory cache), and branches (especially visible to
459 * an adversary who has access to a shared code cache or to a shared
460 * branch predictor). */
461 size_t pad_count = 0;
462 mbedtls_ct_condition_t bad;
463 mbedtls_ct_condition_t pad_done;
464 size_t plaintext_size = 0;
465 mbedtls_ct_condition_t output_too_large;
466
467 plaintext_max_size = (output_max_len > ilen - 11) ? ilen - 11
468 : output_max_len;
469
470 /* Check and get padding length in constant time and constant
471 * memory trace. The first byte must be 0. */
472 bad = mbedtls_ct_bool(input[0]);
473
474
475 /* Decode EME-PKCS1-v1_5 padding: 0x00 || 0x02 || PS || 0x00
476 * where PS must be at least 8 nonzero bytes. */
477 bad = mbedtls_ct_bool_or(bad, mbedtls_ct_uint_ne(input[1], MBEDTLS_RSA_CRYPT));
478
479 /* Read the whole buffer. Set pad_done to nonzero if we find
480 * the 0x00 byte and remember the padding length in pad_count. */
481 pad_done = MBEDTLS_CT_FALSE;
482 for (i = 2; i < ilen; i++) {
483 mbedtls_ct_condition_t found = mbedtls_ct_uint_eq(input[i], 0);
484 pad_done = mbedtls_ct_bool_or(pad_done, found);
485 pad_count += mbedtls_ct_uint_if_else_0(mbedtls_ct_bool_not(pad_done), 1);
486 }
487
488 /* If pad_done is still zero, there's no data, only unfinished padding. */
489 bad = mbedtls_ct_bool_or(bad, mbedtls_ct_bool_not(pad_done));
490
491 /* There must be at least 8 bytes of padding. */
492 bad = mbedtls_ct_bool_or(bad, mbedtls_ct_uint_gt(8, pad_count));
493
494 /* If the padding is valid, set plaintext_size to the number of
495 * remaining bytes after stripping the padding. If the padding
496 * is invalid, avoid leaking this fact through the size of the
497 * output: use the maximum message size that fits in the output
498 * buffer. Do it without branches to avoid leaking the padding
499 * validity through timing. RSA keys are small enough that all the
500 * size_t values involved fit in unsigned int. */
501 plaintext_size = mbedtls_ct_uint_if(
502 bad, (unsigned) plaintext_max_size,
503 (unsigned) (ilen - pad_count - 3));
504
505 /* Set output_too_large to 0 if the plaintext fits in the output
506 * buffer and to 1 otherwise. */
507 output_too_large = mbedtls_ct_uint_gt(plaintext_size,
508 plaintext_max_size);
509
510 /* Set ret without branches to avoid timing attacks. Return:
511 * - INVALID_PADDING if the padding is bad (bad != 0).
512 * - OUTPUT_TOO_LARGE if the padding is good but the decrypted
513 * plaintext does not fit in the output buffer.
514 * - 0 if the padding is correct. */
515 ret = mbedtls_ct_error_if(
516 bad,
517 MBEDTLS_ERR_RSA_INVALID_PADDING,
518 mbedtls_ct_error_if_else_0(output_too_large, MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE)
519 );
520
521 /* If the padding is bad or the plaintext is too large, zero the
522 * data that we're about to copy to the output buffer.
523 * We need to copy the same amount of data
524 * from the same buffer whether the padding is good or not to
525 * avoid leaking the padding validity through overall timing or
526 * through memory or cache access patterns. */
527 mbedtls_ct_zeroize_if(mbedtls_ct_bool_or(bad, output_too_large), input + 11, ilen - 11);
528
529 /* If the plaintext is too large, truncate it to the buffer size.
530 * Copy anyway to avoid revealing the length through timing, because
531 * revealing the length is as bad as revealing the padding validity
532 * for a Bleichenbacher attack. */
533 plaintext_size = mbedtls_ct_uint_if(output_too_large,
534 (unsigned) plaintext_max_size,
535 (unsigned) plaintext_size);
536
537 /* Move the plaintext to the leftmost position where it can start in
538 * the working buffer, i.e. make it start plaintext_max_size from
539 * the end of the buffer. Do this with a memory access trace that
540 * does not depend on the plaintext size. After this move, the
541 * starting location of the plaintext is no longer sensitive
542 * information. */
543 mbedtls_ct_memmove_left(input + ilen - plaintext_max_size,
544 plaintext_max_size,
545 plaintext_max_size - plaintext_size);
546
547 /* Finally copy the decrypted plaintext plus trailing zeros into the output
548 * buffer. If output_max_len is 0, then output may be an invalid pointer
549 * and the result of memcpy() would be undefined; prevent undefined
550 * behavior making sure to depend only on output_max_len (the size of the
551 * user-provided output buffer), which is independent from plaintext
552 * length, validity of padding, success of the decryption, and other
553 * secrets. */
554 if (output_max_len != 0) {
555 memcpy(output, input + ilen - plaintext_max_size, plaintext_max_size);
556 }
557
558 /* Report the amount of data we copied to the output buffer. In case
559 * of errors (bad padding or output too large), the value of *olen
560 * when this function returns is not specified. Making it equivalent
561 * to the good case limits the risks of leaking the padding validity. */
562 *olen = plaintext_size;
563
564 return ret;
565 }
566
567 #endif /* MBEDTLS_PKCS1_V15 && MBEDTLS_RSA_C && ! MBEDTLS_RSA_ALT */
568
569 #if !defined(MBEDTLS_RSA_ALT)
570
mbedtls_rsa_import(mbedtls_rsa_context * ctx,const mbedtls_mpi * N,const mbedtls_mpi * P,const mbedtls_mpi * Q,const mbedtls_mpi * D,const mbedtls_mpi * E)571 int mbedtls_rsa_import(mbedtls_rsa_context *ctx,
572 const mbedtls_mpi *N,
573 const mbedtls_mpi *P, const mbedtls_mpi *Q,
574 const mbedtls_mpi *D, const mbedtls_mpi *E)
575 {
576 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
577
578 if ((N != NULL && (ret = mbedtls_mpi_copy(&ctx->N, N)) != 0) ||
579 (P != NULL && (ret = mbedtls_mpi_copy(&ctx->P, P)) != 0) ||
580 (Q != NULL && (ret = mbedtls_mpi_copy(&ctx->Q, Q)) != 0) ||
581 (D != NULL && (ret = mbedtls_mpi_copy(&ctx->D, D)) != 0) ||
582 (E != NULL && (ret = mbedtls_mpi_copy(&ctx->E, E)) != 0)) {
583 return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret);
584 }
585
586 if (N != NULL) {
587 ctx->len = mbedtls_mpi_size(&ctx->N);
588 }
589
590 return 0;
591 }
592
mbedtls_rsa_import_raw(mbedtls_rsa_context * ctx,unsigned char const * N,size_t N_len,unsigned char const * P,size_t P_len,unsigned char const * Q,size_t Q_len,unsigned char const * D,size_t D_len,unsigned char const * E,size_t E_len)593 int mbedtls_rsa_import_raw(mbedtls_rsa_context *ctx,
594 unsigned char const *N, size_t N_len,
595 unsigned char const *P, size_t P_len,
596 unsigned char const *Q, size_t Q_len,
597 unsigned char const *D, size_t D_len,
598 unsigned char const *E, size_t E_len)
599 {
600 int ret = 0;
601
602 if (N != NULL) {
603 MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(&ctx->N, N, N_len));
604 ctx->len = mbedtls_mpi_size(&ctx->N);
605 }
606
607 if (P != NULL) {
608 MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(&ctx->P, P, P_len));
609 }
610
611 if (Q != NULL) {
612 MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(&ctx->Q, Q, Q_len));
613 }
614
615 if (D != NULL) {
616 MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(&ctx->D, D, D_len));
617 }
618
619 if (E != NULL) {
620 MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(&ctx->E, E, E_len));
621 }
622
623 cleanup:
624
625 if (ret != 0) {
626 return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret);
627 }
628
629 return 0;
630 }
631
632 /*
633 * Checks whether the context fields are set in such a way
634 * that the RSA primitives will be able to execute without error.
635 * It does *not* make guarantees for consistency of the parameters.
636 */
rsa_check_context(mbedtls_rsa_context const * ctx,int is_priv,int blinding_needed)637 static int rsa_check_context(mbedtls_rsa_context const *ctx, int is_priv,
638 int blinding_needed)
639 {
640 #if !defined(MBEDTLS_RSA_NO_CRT)
641 /* blinding_needed is only used for NO_CRT to decide whether
642 * P,Q need to be present or not. */
643 ((void) blinding_needed);
644 #endif
645
646 if (ctx->len != mbedtls_mpi_size(&ctx->N) ||
647 ctx->len > MBEDTLS_MPI_MAX_SIZE) {
648 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
649 }
650
651 /*
652 * 1. Modular exponentiation needs positive, odd moduli.
653 */
654
655 /* Modular exponentiation wrt. N is always used for
656 * RSA public key operations. */
657 if (mbedtls_mpi_cmp_int(&ctx->N, 0) <= 0 ||
658 mbedtls_mpi_get_bit(&ctx->N, 0) == 0) {
659 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
660 }
661
662 #if !defined(MBEDTLS_RSA_NO_CRT)
663 /* Modular exponentiation for P and Q is only
664 * used for private key operations and if CRT
665 * is used. */
666 if (is_priv &&
667 (mbedtls_mpi_cmp_int(&ctx->P, 0) <= 0 ||
668 mbedtls_mpi_get_bit(&ctx->P, 0) == 0 ||
669 mbedtls_mpi_cmp_int(&ctx->Q, 0) <= 0 ||
670 mbedtls_mpi_get_bit(&ctx->Q, 0) == 0)) {
671 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
672 }
673 #endif /* !MBEDTLS_RSA_NO_CRT */
674
675 /*
676 * 2. Exponents must be positive
677 */
678
679 /* Always need E for public key operations */
680 if (mbedtls_mpi_cmp_int(&ctx->E, 0) <= 0) {
681 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
682 }
683
684 #if defined(MBEDTLS_RSA_NO_CRT)
685 /* For private key operations, use D or DP & DQ
686 * as (unblinded) exponents. */
687 if (is_priv && mbedtls_mpi_cmp_int(&ctx->D, 0) <= 0) {
688 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
689 }
690 #else
691 if (is_priv &&
692 (mbedtls_mpi_cmp_int(&ctx->DP, 0) <= 0 ||
693 mbedtls_mpi_cmp_int(&ctx->DQ, 0) <= 0)) {
694 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
695 }
696 #endif /* MBEDTLS_RSA_NO_CRT */
697
698 /* Blinding shouldn't make exponents negative either,
699 * so check that P, Q >= 1 if that hasn't yet been
700 * done as part of 1. */
701 #if defined(MBEDTLS_RSA_NO_CRT)
702 if (is_priv && blinding_needed &&
703 (mbedtls_mpi_cmp_int(&ctx->P, 0) <= 0 ||
704 mbedtls_mpi_cmp_int(&ctx->Q, 0) <= 0)) {
705 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
706 }
707 #endif
708
709 /* It wouldn't lead to an error if it wasn't satisfied,
710 * but check for QP >= 1 nonetheless. */
711 #if !defined(MBEDTLS_RSA_NO_CRT)
712 if (is_priv &&
713 mbedtls_mpi_cmp_int(&ctx->QP, 0) <= 0) {
714 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
715 }
716 #endif
717
718 return 0;
719 }
720
mbedtls_rsa_complete(mbedtls_rsa_context * ctx)721 int mbedtls_rsa_complete(mbedtls_rsa_context *ctx)
722 {
723 int ret = 0;
724 int have_N, have_P, have_Q, have_D, have_E;
725 #if !defined(MBEDTLS_RSA_NO_CRT)
726 int have_DP, have_DQ, have_QP;
727 #endif
728 int n_missing, pq_missing, d_missing, is_pub, is_priv;
729
730 have_N = (mbedtls_mpi_cmp_int(&ctx->N, 0) != 0);
731 have_P = (mbedtls_mpi_cmp_int(&ctx->P, 0) != 0);
732 have_Q = (mbedtls_mpi_cmp_int(&ctx->Q, 0) != 0);
733 have_D = (mbedtls_mpi_cmp_int(&ctx->D, 0) != 0);
734 have_E = (mbedtls_mpi_cmp_int(&ctx->E, 0) != 0);
735
736 #if !defined(MBEDTLS_RSA_NO_CRT)
737 have_DP = (mbedtls_mpi_cmp_int(&ctx->DP, 0) != 0);
738 have_DQ = (mbedtls_mpi_cmp_int(&ctx->DQ, 0) != 0);
739 have_QP = (mbedtls_mpi_cmp_int(&ctx->QP, 0) != 0);
740 #endif
741
742 /*
743 * Check whether provided parameters are enough
744 * to deduce all others. The following incomplete
745 * parameter sets for private keys are supported:
746 *
747 * (1) P, Q missing.
748 * (2) D and potentially N missing.
749 *
750 */
751
752 n_missing = have_P && have_Q && have_D && have_E;
753 pq_missing = have_N && !have_P && !have_Q && have_D && have_E;
754 d_missing = have_P && have_Q && !have_D && have_E;
755 is_pub = have_N && !have_P && !have_Q && !have_D && have_E;
756
757 /* These three alternatives are mutually exclusive */
758 is_priv = n_missing || pq_missing || d_missing;
759
760 if (!is_priv && !is_pub) {
761 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
762 }
763
764 /*
765 * Step 1: Deduce N if P, Q are provided.
766 */
767
768 if (!have_N && have_P && have_Q) {
769 if ((ret = mbedtls_mpi_mul_mpi(&ctx->N, &ctx->P,
770 &ctx->Q)) != 0) {
771 return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret);
772 }
773
774 ctx->len = mbedtls_mpi_size(&ctx->N);
775 }
776
777 /*
778 * Step 2: Deduce and verify all remaining core parameters.
779 */
780
781 if (pq_missing) {
782 ret = mbedtls_rsa_deduce_primes(&ctx->N, &ctx->E, &ctx->D,
783 &ctx->P, &ctx->Q);
784 if (ret != 0) {
785 return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret);
786 }
787
788 } else if (d_missing) {
789 if ((ret = mbedtls_rsa_deduce_private_exponent(&ctx->P,
790 &ctx->Q,
791 &ctx->E,
792 &ctx->D)) != 0) {
793 return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret);
794 }
795 }
796
797 /*
798 * Step 3: Deduce all additional parameters specific
799 * to our current RSA implementation.
800 */
801
802 #if !defined(MBEDTLS_RSA_NO_CRT)
803 if (is_priv && !(have_DP && have_DQ && have_QP)) {
804 ret = mbedtls_rsa_deduce_crt(&ctx->P, &ctx->Q, &ctx->D,
805 &ctx->DP, &ctx->DQ, &ctx->QP);
806 if (ret != 0) {
807 return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret);
808 }
809 }
810 #endif /* MBEDTLS_RSA_NO_CRT */
811
812 /*
813 * Step 3: Basic sanity checks
814 */
815
816 return rsa_check_context(ctx, is_priv, 1);
817 }
818
mbedtls_rsa_export_raw(const mbedtls_rsa_context * ctx,unsigned char * N,size_t N_len,unsigned char * P,size_t P_len,unsigned char * Q,size_t Q_len,unsigned char * D,size_t D_len,unsigned char * E,size_t E_len)819 int mbedtls_rsa_export_raw(const mbedtls_rsa_context *ctx,
820 unsigned char *N, size_t N_len,
821 unsigned char *P, size_t P_len,
822 unsigned char *Q, size_t Q_len,
823 unsigned char *D, size_t D_len,
824 unsigned char *E, size_t E_len)
825 {
826 int ret = 0;
827 int is_priv;
828
829 /* Check if key is private or public */
830 is_priv =
831 mbedtls_mpi_cmp_int(&ctx->N, 0) != 0 &&
832 mbedtls_mpi_cmp_int(&ctx->P, 0) != 0 &&
833 mbedtls_mpi_cmp_int(&ctx->Q, 0) != 0 &&
834 mbedtls_mpi_cmp_int(&ctx->D, 0) != 0 &&
835 mbedtls_mpi_cmp_int(&ctx->E, 0) != 0;
836
837 if (!is_priv) {
838 /* If we're trying to export private parameters for a public key,
839 * something must be wrong. */
840 if (P != NULL || Q != NULL || D != NULL) {
841 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
842 }
843
844 }
845
846 if (N != NULL) {
847 MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary(&ctx->N, N, N_len));
848 }
849
850 if (P != NULL) {
851 MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary(&ctx->P, P, P_len));
852 }
853
854 if (Q != NULL) {
855 MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary(&ctx->Q, Q, Q_len));
856 }
857
858 if (D != NULL) {
859 MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary(&ctx->D, D, D_len));
860 }
861
862 if (E != NULL) {
863 MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary(&ctx->E, E, E_len));
864 }
865
866 cleanup:
867
868 return ret;
869 }
870
mbedtls_rsa_export(const mbedtls_rsa_context * ctx,mbedtls_mpi * N,mbedtls_mpi * P,mbedtls_mpi * Q,mbedtls_mpi * D,mbedtls_mpi * E)871 int mbedtls_rsa_export(const mbedtls_rsa_context *ctx,
872 mbedtls_mpi *N, mbedtls_mpi *P, mbedtls_mpi *Q,
873 mbedtls_mpi *D, mbedtls_mpi *E)
874 {
875 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
876 int is_priv;
877
878 /* Check if key is private or public */
879 is_priv =
880 mbedtls_mpi_cmp_int(&ctx->N, 0) != 0 &&
881 mbedtls_mpi_cmp_int(&ctx->P, 0) != 0 &&
882 mbedtls_mpi_cmp_int(&ctx->Q, 0) != 0 &&
883 mbedtls_mpi_cmp_int(&ctx->D, 0) != 0 &&
884 mbedtls_mpi_cmp_int(&ctx->E, 0) != 0;
885
886 if (!is_priv) {
887 /* If we're trying to export private parameters for a public key,
888 * something must be wrong. */
889 if (P != NULL || Q != NULL || D != NULL) {
890 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
891 }
892
893 }
894
895 /* Export all requested core parameters. */
896
897 if ((N != NULL && (ret = mbedtls_mpi_copy(N, &ctx->N)) != 0) ||
898 (P != NULL && (ret = mbedtls_mpi_copy(P, &ctx->P)) != 0) ||
899 (Q != NULL && (ret = mbedtls_mpi_copy(Q, &ctx->Q)) != 0) ||
900 (D != NULL && (ret = mbedtls_mpi_copy(D, &ctx->D)) != 0) ||
901 (E != NULL && (ret = mbedtls_mpi_copy(E, &ctx->E)) != 0)) {
902 return ret;
903 }
904
905 return 0;
906 }
907
908 /*
909 * Export CRT parameters
910 * This must also be implemented if CRT is not used, for being able to
911 * write DER encoded RSA keys. The helper function mbedtls_rsa_deduce_crt
912 * can be used in this case.
913 */
mbedtls_rsa_export_crt(const mbedtls_rsa_context * ctx,mbedtls_mpi * DP,mbedtls_mpi * DQ,mbedtls_mpi * QP)914 int mbedtls_rsa_export_crt(const mbedtls_rsa_context *ctx,
915 mbedtls_mpi *DP, mbedtls_mpi *DQ, mbedtls_mpi *QP)
916 {
917 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
918 int is_priv;
919
920 /* Check if key is private or public */
921 is_priv =
922 mbedtls_mpi_cmp_int(&ctx->N, 0) != 0 &&
923 mbedtls_mpi_cmp_int(&ctx->P, 0) != 0 &&
924 mbedtls_mpi_cmp_int(&ctx->Q, 0) != 0 &&
925 mbedtls_mpi_cmp_int(&ctx->D, 0) != 0 &&
926 mbedtls_mpi_cmp_int(&ctx->E, 0) != 0;
927
928 if (!is_priv) {
929 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
930 }
931
932 #if !defined(MBEDTLS_RSA_NO_CRT)
933 /* Export all requested blinding parameters. */
934 if ((DP != NULL && (ret = mbedtls_mpi_copy(DP, &ctx->DP)) != 0) ||
935 (DQ != NULL && (ret = mbedtls_mpi_copy(DQ, &ctx->DQ)) != 0) ||
936 (QP != NULL && (ret = mbedtls_mpi_copy(QP, &ctx->QP)) != 0)) {
937 return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret);
938 }
939 #else
940 if ((ret = mbedtls_rsa_deduce_crt(&ctx->P, &ctx->Q, &ctx->D,
941 DP, DQ, QP)) != 0) {
942 return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_RSA_BAD_INPUT_DATA, ret);
943 }
944 #endif
945
946 return 0;
947 }
948
949 /*
950 * Initialize an RSA context
951 */
mbedtls_rsa_init(mbedtls_rsa_context * ctx)952 void mbedtls_rsa_init(mbedtls_rsa_context *ctx)
953 {
954 memset(ctx, 0, sizeof(mbedtls_rsa_context));
955
956 ctx->padding = MBEDTLS_RSA_PKCS_V15;
957 ctx->hash_id = MBEDTLS_MD_NONE;
958
959 #if defined(MBEDTLS_THREADING_C)
960 /* Set ctx->ver to nonzero to indicate that the mutex has been
961 * initialized and will need to be freed. */
962 ctx->ver = 1;
963 mbedtls_mutex_init(&ctx->mutex);
964 #endif
965 }
966
967 /*
968 * Set padding for an existing RSA context
969 */
mbedtls_rsa_set_padding(mbedtls_rsa_context * ctx,int padding,mbedtls_md_type_t hash_id)970 int mbedtls_rsa_set_padding(mbedtls_rsa_context *ctx, int padding,
971 mbedtls_md_type_t hash_id)
972 {
973 switch (padding) {
974 #if defined(MBEDTLS_PKCS1_V15)
975 case MBEDTLS_RSA_PKCS_V15:
976 break;
977 #endif
978
979 #if defined(MBEDTLS_PKCS1_V21)
980 case MBEDTLS_RSA_PKCS_V21:
981 break;
982 #endif
983 default:
984 return MBEDTLS_ERR_RSA_INVALID_PADDING;
985 }
986
987 #if defined(MBEDTLS_PKCS1_V21)
988 if ((padding == MBEDTLS_RSA_PKCS_V21) &&
989 (hash_id != MBEDTLS_MD_NONE)) {
990 /* Just make sure this hash is supported in this build. */
991 if (mbedtls_md_info_from_type(hash_id) == NULL) {
992 return MBEDTLS_ERR_RSA_INVALID_PADDING;
993 }
994 }
995 #endif /* MBEDTLS_PKCS1_V21 */
996
997 ctx->padding = padding;
998 ctx->hash_id = hash_id;
999
1000 return 0;
1001 }
1002
1003 /*
1004 * Get padding mode of initialized RSA context
1005 */
mbedtls_rsa_get_padding_mode(const mbedtls_rsa_context * ctx)1006 int mbedtls_rsa_get_padding_mode(const mbedtls_rsa_context *ctx)
1007 {
1008 return ctx->padding;
1009 }
1010
1011 /*
1012 * Get hash identifier of mbedtls_md_type_t type
1013 */
mbedtls_rsa_get_md_alg(const mbedtls_rsa_context * ctx)1014 int mbedtls_rsa_get_md_alg(const mbedtls_rsa_context *ctx)
1015 {
1016 return ctx->hash_id;
1017 }
1018
1019 /*
1020 * Get length in bits of RSA modulus
1021 */
mbedtls_rsa_get_bitlen(const mbedtls_rsa_context * ctx)1022 size_t mbedtls_rsa_get_bitlen(const mbedtls_rsa_context *ctx)
1023 {
1024 return mbedtls_mpi_bitlen(&ctx->N);
1025 }
1026
1027 /*
1028 * Get length in bytes of RSA modulus
1029 */
mbedtls_rsa_get_len(const mbedtls_rsa_context * ctx)1030 size_t mbedtls_rsa_get_len(const mbedtls_rsa_context *ctx)
1031 {
1032 return ctx->len;
1033 }
1034
1035 #if defined(MBEDTLS_GENPRIME)
1036
1037 /*
1038 * Generate an RSA keypair
1039 *
1040 * This generation method follows the RSA key pair generation procedure of
1041 * FIPS 186-4 if 2^16 < exponent < 2^256 and nbits = 2048 or nbits = 3072.
1042 */
mbedtls_rsa_gen_key(mbedtls_rsa_context * ctx,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng,unsigned int nbits,int exponent)1043 int mbedtls_rsa_gen_key(mbedtls_rsa_context *ctx,
1044 int (*f_rng)(void *, unsigned char *, size_t),
1045 void *p_rng,
1046 unsigned int nbits, int exponent)
1047 {
1048 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
1049 mbedtls_mpi H, G, L;
1050 int prime_quality = 0;
1051
1052 /*
1053 * If the modulus is 1024 bit long or shorter, then the security strength of
1054 * the RSA algorithm is less than or equal to 80 bits and therefore an error
1055 * rate of 2^-80 is sufficient.
1056 */
1057 if (nbits > 1024) {
1058 prime_quality = MBEDTLS_MPI_GEN_PRIME_FLAG_LOW_ERR;
1059 }
1060
1061 mbedtls_mpi_init(&H);
1062 mbedtls_mpi_init(&G);
1063 mbedtls_mpi_init(&L);
1064
1065 if (exponent < 3 || nbits % 2 != 0) {
1066 ret = MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
1067 goto cleanup;
1068 }
1069
1070 if (nbits < MBEDTLS_RSA_GEN_KEY_MIN_BITS) {
1071 ret = MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
1072 goto cleanup;
1073 }
1074
1075 /*
1076 * find primes P and Q with Q < P so that:
1077 * 1. |P-Q| > 2^( nbits / 2 - 100 )
1078 * 2. GCD( E, (P-1)*(Q-1) ) == 1
1079 * 3. E^-1 mod LCM(P-1, Q-1) > 2^( nbits / 2 )
1080 */
1081 MBEDTLS_MPI_CHK(mbedtls_mpi_lset(&ctx->E, exponent));
1082
1083 do {
1084 MBEDTLS_MPI_CHK(mbedtls_mpi_gen_prime(&ctx->P, nbits >> 1,
1085 prime_quality, f_rng, p_rng));
1086
1087 MBEDTLS_MPI_CHK(mbedtls_mpi_gen_prime(&ctx->Q, nbits >> 1,
1088 prime_quality, f_rng, p_rng));
1089
1090 /* make sure the difference between p and q is not too small (FIPS 186-4 §B.3.3 step 5.4) */
1091 MBEDTLS_MPI_CHK(mbedtls_mpi_sub_mpi(&H, &ctx->P, &ctx->Q));
1092 if (mbedtls_mpi_bitlen(&H) <= ((nbits >= 200) ? ((nbits >> 1) - 99) : 0)) {
1093 continue;
1094 }
1095
1096 /* not required by any standards, but some users rely on the fact that P > Q */
1097 if (H.s < 0) {
1098 mbedtls_mpi_swap(&ctx->P, &ctx->Q);
1099 }
1100
1101 /* Temporarily replace P,Q by P-1, Q-1 */
1102 MBEDTLS_MPI_CHK(mbedtls_mpi_sub_int(&ctx->P, &ctx->P, 1));
1103 MBEDTLS_MPI_CHK(mbedtls_mpi_sub_int(&ctx->Q, &ctx->Q, 1));
1104 MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&H, &ctx->P, &ctx->Q));
1105
1106 /* check GCD( E, (P-1)*(Q-1) ) == 1 (FIPS 186-4 §B.3.1 criterion 2(a)) */
1107 MBEDTLS_MPI_CHK(mbedtls_mpi_gcd(&G, &ctx->E, &H));
1108 if (mbedtls_mpi_cmp_int(&G, 1) != 0) {
1109 continue;
1110 }
1111
1112 /* compute smallest possible D = E^-1 mod LCM(P-1, Q-1) (FIPS 186-4 §B.3.1 criterion 3(b)) */
1113 MBEDTLS_MPI_CHK(mbedtls_mpi_gcd(&G, &ctx->P, &ctx->Q));
1114 MBEDTLS_MPI_CHK(mbedtls_mpi_div_mpi(&L, NULL, &H, &G));
1115 MBEDTLS_MPI_CHK(mbedtls_mpi_inv_mod(&ctx->D, &ctx->E, &L));
1116
1117 if (mbedtls_mpi_bitlen(&ctx->D) <= ((nbits + 1) / 2)) { // (FIPS 186-4 §B.3.1 criterion 3(a))
1118 continue;
1119 }
1120
1121 break;
1122 } while (1);
1123
1124 /* Restore P,Q */
1125 MBEDTLS_MPI_CHK(mbedtls_mpi_add_int(&ctx->P, &ctx->P, 1));
1126 MBEDTLS_MPI_CHK(mbedtls_mpi_add_int(&ctx->Q, &ctx->Q, 1));
1127
1128 MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&ctx->N, &ctx->P, &ctx->Q));
1129
1130 ctx->len = mbedtls_mpi_size(&ctx->N);
1131
1132 #if !defined(MBEDTLS_RSA_NO_CRT)
1133 /*
1134 * DP = D mod (P - 1)
1135 * DQ = D mod (Q - 1)
1136 * QP = Q^-1 mod P
1137 */
1138 MBEDTLS_MPI_CHK(mbedtls_rsa_deduce_crt(&ctx->P, &ctx->Q, &ctx->D,
1139 &ctx->DP, &ctx->DQ, &ctx->QP));
1140 #endif /* MBEDTLS_RSA_NO_CRT */
1141
1142 /* Double-check */
1143 MBEDTLS_MPI_CHK(mbedtls_rsa_check_privkey(ctx));
1144
1145 cleanup:
1146
1147 mbedtls_mpi_free(&H);
1148 mbedtls_mpi_free(&G);
1149 mbedtls_mpi_free(&L);
1150
1151 if (ret != 0) {
1152 mbedtls_rsa_free(ctx);
1153
1154 if ((-ret & ~0x7f) == 0) {
1155 ret = MBEDTLS_ERROR_ADD(MBEDTLS_ERR_RSA_KEY_GEN_FAILED, ret);
1156 }
1157 return ret;
1158 }
1159
1160 return 0;
1161 }
1162
1163 #endif /* MBEDTLS_GENPRIME */
1164
1165 /*
1166 * Check a public RSA key
1167 */
mbedtls_rsa_check_pubkey(const mbedtls_rsa_context * ctx)1168 int mbedtls_rsa_check_pubkey(const mbedtls_rsa_context *ctx)
1169 {
1170 if (rsa_check_context(ctx, 0 /* public */, 0 /* no blinding */) != 0) {
1171 return MBEDTLS_ERR_RSA_KEY_CHECK_FAILED;
1172 }
1173
1174 if (mbedtls_mpi_bitlen(&ctx->N) < 128) {
1175 return MBEDTLS_ERR_RSA_KEY_CHECK_FAILED;
1176 }
1177
1178 if (mbedtls_mpi_get_bit(&ctx->E, 0) == 0 ||
1179 mbedtls_mpi_bitlen(&ctx->E) < 2 ||
1180 mbedtls_mpi_cmp_mpi(&ctx->E, &ctx->N) >= 0) {
1181 return MBEDTLS_ERR_RSA_KEY_CHECK_FAILED;
1182 }
1183
1184 return 0;
1185 }
1186
1187 /*
1188 * Check for the consistency of all fields in an RSA private key context
1189 */
mbedtls_rsa_check_privkey(const mbedtls_rsa_context * ctx)1190 int mbedtls_rsa_check_privkey(const mbedtls_rsa_context *ctx)
1191 {
1192 if (mbedtls_rsa_check_pubkey(ctx) != 0 ||
1193 rsa_check_context(ctx, 1 /* private */, 1 /* blinding */) != 0) {
1194 return MBEDTLS_ERR_RSA_KEY_CHECK_FAILED;
1195 }
1196
1197 if (mbedtls_rsa_validate_params(&ctx->N, &ctx->P, &ctx->Q,
1198 &ctx->D, &ctx->E, NULL, NULL) != 0) {
1199 return MBEDTLS_ERR_RSA_KEY_CHECK_FAILED;
1200 }
1201
1202 #if !defined(MBEDTLS_RSA_NO_CRT)
1203 else if (mbedtls_rsa_validate_crt(&ctx->P, &ctx->Q, &ctx->D,
1204 &ctx->DP, &ctx->DQ, &ctx->QP) != 0) {
1205 return MBEDTLS_ERR_RSA_KEY_CHECK_FAILED;
1206 }
1207 #endif
1208
1209 return 0;
1210 }
1211
1212 /*
1213 * Check if contexts holding a public and private key match
1214 */
mbedtls_rsa_check_pub_priv(const mbedtls_rsa_context * pub,const mbedtls_rsa_context * prv)1215 int mbedtls_rsa_check_pub_priv(const mbedtls_rsa_context *pub,
1216 const mbedtls_rsa_context *prv)
1217 {
1218 if (mbedtls_rsa_check_pubkey(pub) != 0 ||
1219 mbedtls_rsa_check_privkey(prv) != 0) {
1220 return MBEDTLS_ERR_RSA_KEY_CHECK_FAILED;
1221 }
1222
1223 if (mbedtls_mpi_cmp_mpi(&pub->N, &prv->N) != 0 ||
1224 mbedtls_mpi_cmp_mpi(&pub->E, &prv->E) != 0) {
1225 return MBEDTLS_ERR_RSA_KEY_CHECK_FAILED;
1226 }
1227
1228 return 0;
1229 }
1230
1231 /*
1232 * Do an RSA public key operation
1233 */
mbedtls_rsa_public(mbedtls_rsa_context * ctx,const unsigned char * input,unsigned char * output)1234 int mbedtls_rsa_public(mbedtls_rsa_context *ctx,
1235 const unsigned char *input,
1236 unsigned char *output)
1237 {
1238 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
1239 size_t olen;
1240 mbedtls_mpi T;
1241
1242 if (rsa_check_context(ctx, 0 /* public */, 0 /* no blinding */)) {
1243 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
1244 }
1245
1246 mbedtls_mpi_init(&T);
1247
1248 #if defined(MBEDTLS_THREADING_C)
1249 if ((ret = mbedtls_mutex_lock(&ctx->mutex)) != 0) {
1250 return ret;
1251 }
1252 #endif
1253
1254 MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(&T, input, ctx->len));
1255
1256 if (mbedtls_mpi_cmp_mpi(&T, &ctx->N) >= 0) {
1257 ret = MBEDTLS_ERR_MPI_BAD_INPUT_DATA;
1258 goto cleanup;
1259 }
1260
1261 olen = ctx->len;
1262 MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&T, &T, &ctx->E, &ctx->N, &ctx->RN));
1263 MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary(&T, output, olen));
1264
1265 cleanup:
1266 #if defined(MBEDTLS_THREADING_C)
1267 if (mbedtls_mutex_unlock(&ctx->mutex) != 0) {
1268 return MBEDTLS_ERR_THREADING_MUTEX_ERROR;
1269 }
1270 #endif
1271
1272 mbedtls_mpi_free(&T);
1273
1274 if (ret != 0) {
1275 return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_RSA_PUBLIC_FAILED, ret);
1276 }
1277
1278 return 0;
1279 }
1280
1281 /*
1282 * Generate or update blinding values, see section 10 of:
1283 * KOCHER, Paul C. Timing attacks on implementations of Diffie-Hellman, RSA,
1284 * DSS, and other systems. In : Advances in Cryptology-CRYPTO'96. Springer
1285 * Berlin Heidelberg, 1996. p. 104-113.
1286 */
rsa_prepare_blinding(mbedtls_rsa_context * ctx,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng)1287 static int rsa_prepare_blinding(mbedtls_rsa_context *ctx,
1288 int (*f_rng)(void *, unsigned char *, size_t), void *p_rng)
1289 {
1290 int ret, count = 0;
1291 mbedtls_mpi R;
1292
1293 mbedtls_mpi_init(&R);
1294
1295 if (ctx->Vf.p != NULL) {
1296 /* We already have blinding values, just update them by squaring */
1297 MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&ctx->Vi, &ctx->Vi, &ctx->Vi));
1298 MBEDTLS_MPI_CHK(mbedtls_mpi_mod_mpi(&ctx->Vi, &ctx->Vi, &ctx->N));
1299 MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&ctx->Vf, &ctx->Vf, &ctx->Vf));
1300 MBEDTLS_MPI_CHK(mbedtls_mpi_mod_mpi(&ctx->Vf, &ctx->Vf, &ctx->N));
1301
1302 goto cleanup;
1303 }
1304
1305 /* Unblinding value: Vf = random number, invertible mod N */
1306 do {
1307 if (count++ > 10) {
1308 ret = MBEDTLS_ERR_RSA_RNG_FAILED;
1309 goto cleanup;
1310 }
1311
1312 MBEDTLS_MPI_CHK(mbedtls_mpi_fill_random(&ctx->Vf, ctx->len - 1, f_rng, p_rng));
1313
1314 /* Compute Vf^-1 as R * (R Vf)^-1 to avoid leaks from inv_mod. */
1315 MBEDTLS_MPI_CHK(mbedtls_mpi_fill_random(&R, ctx->len - 1, f_rng, p_rng));
1316 MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&ctx->Vi, &ctx->Vf, &R));
1317 MBEDTLS_MPI_CHK(mbedtls_mpi_mod_mpi(&ctx->Vi, &ctx->Vi, &ctx->N));
1318
1319 /* At this point, Vi is invertible mod N if and only if both Vf and R
1320 * are invertible mod N. If one of them isn't, we don't need to know
1321 * which one, we just loop and choose new values for both of them.
1322 * (Each iteration succeeds with overwhelming probability.) */
1323 ret = mbedtls_mpi_inv_mod(&ctx->Vi, &ctx->Vi, &ctx->N);
1324 if (ret != 0 && ret != MBEDTLS_ERR_MPI_NOT_ACCEPTABLE) {
1325 goto cleanup;
1326 }
1327
1328 } while (ret == MBEDTLS_ERR_MPI_NOT_ACCEPTABLE);
1329
1330 /* Finish the computation of Vf^-1 = R * (R Vf)^-1 */
1331 MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&ctx->Vi, &ctx->Vi, &R));
1332 MBEDTLS_MPI_CHK(mbedtls_mpi_mod_mpi(&ctx->Vi, &ctx->Vi, &ctx->N));
1333
1334 /* Blinding value: Vi = Vf^(-e) mod N
1335 * (Vi already contains Vf^-1 at this point) */
1336 MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&ctx->Vi, &ctx->Vi, &ctx->E, &ctx->N, &ctx->RN));
1337
1338
1339 cleanup:
1340 mbedtls_mpi_free(&R);
1341
1342 return ret;
1343 }
1344
1345 /*
1346 * Unblind
1347 * T = T * Vf mod N
1348 */
rsa_unblind(mbedtls_mpi * T,mbedtls_mpi * Vf,const mbedtls_mpi * N)1349 static int rsa_unblind(mbedtls_mpi *T, mbedtls_mpi *Vf, const mbedtls_mpi *N)
1350 {
1351 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
1352 const mbedtls_mpi_uint mm = mbedtls_mpi_core_montmul_init(N->p);
1353 const size_t nlimbs = N->n;
1354 const size_t tlimbs = mbedtls_mpi_core_montmul_working_limbs(nlimbs);
1355 mbedtls_mpi RR, M_T;
1356
1357 mbedtls_mpi_init(&RR);
1358 mbedtls_mpi_init(&M_T);
1359
1360 MBEDTLS_MPI_CHK(mbedtls_mpi_core_get_mont_r2_unsafe(&RR, N));
1361 MBEDTLS_MPI_CHK(mbedtls_mpi_grow(&M_T, tlimbs));
1362
1363 MBEDTLS_MPI_CHK(mbedtls_mpi_grow(T, nlimbs));
1364 MBEDTLS_MPI_CHK(mbedtls_mpi_grow(Vf, nlimbs));
1365
1366 /* T = T * Vf mod N
1367 * Reminder: montmul(A, B, N) = A * B * R^-1 mod N
1368 * Usually both operands are multiplied by R mod N beforehand (by calling
1369 * `to_mont_rep()` on them), yielding a result that's also * R mod N (aka
1370 * "in the Montgomery domain"). Here we only multiply one operand by R mod
1371 * N, so the result is directly what we want - no need to call
1372 * `from_mont_rep()` on it. */
1373 mbedtls_mpi_core_to_mont_rep(T->p, T->p, N->p, nlimbs, mm, RR.p, M_T.p);
1374 mbedtls_mpi_core_montmul(T->p, T->p, Vf->p, nlimbs, N->p, nlimbs, mm, M_T.p);
1375
1376 cleanup:
1377
1378 mbedtls_mpi_free(&RR);
1379 mbedtls_mpi_free(&M_T);
1380
1381 return ret;
1382 }
1383
1384 /*
1385 * Exponent blinding supposed to prevent side-channel attacks using multiple
1386 * traces of measurements to recover the RSA key. The more collisions are there,
1387 * the more bits of the key can be recovered. See [3].
1388 *
1389 * Collecting n collisions with m bit long blinding value requires 2^(m-m/n)
1390 * observations on average.
1391 *
1392 * For example with 28 byte blinding to achieve 2 collisions the adversary has
1393 * to make 2^112 observations on average.
1394 *
1395 * (With the currently (as of 2017 April) known best algorithms breaking 2048
1396 * bit RSA requires approximately as much time as trying out 2^112 random keys.
1397 * Thus in this sense with 28 byte blinding the security is not reduced by
1398 * side-channel attacks like the one in [3])
1399 *
1400 * This countermeasure does not help if the key recovery is possible with a
1401 * single trace.
1402 */
1403 #define RSA_EXPONENT_BLINDING 28
1404
1405 /*
1406 * Do an RSA private key operation
1407 */
mbedtls_rsa_private(mbedtls_rsa_context * ctx,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng,const unsigned char * input,unsigned char * output)1408 int mbedtls_rsa_private(mbedtls_rsa_context *ctx,
1409 int (*f_rng)(void *, unsigned char *, size_t),
1410 void *p_rng,
1411 const unsigned char *input,
1412 unsigned char *output)
1413 {
1414 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
1415 size_t olen;
1416
1417 /* Temporary holding the result */
1418 mbedtls_mpi T;
1419
1420 /* Temporaries holding P-1, Q-1 and the
1421 * exponent blinding factor, respectively. */
1422 mbedtls_mpi P1, Q1, R;
1423
1424 #if !defined(MBEDTLS_RSA_NO_CRT)
1425 /* Temporaries holding the results mod p resp. mod q. */
1426 mbedtls_mpi TP, TQ;
1427
1428 /* Temporaries holding the blinded exponents for
1429 * the mod p resp. mod q computation (if used). */
1430 mbedtls_mpi DP_blind, DQ_blind;
1431 #else
1432 /* Temporary holding the blinded exponent (if used). */
1433 mbedtls_mpi D_blind;
1434 #endif /* MBEDTLS_RSA_NO_CRT */
1435
1436 /* Temporaries holding the initial input and the double
1437 * checked result; should be the same in the end. */
1438 mbedtls_mpi input_blinded, check_result_blinded;
1439
1440 if (f_rng == NULL) {
1441 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
1442 }
1443
1444 if (rsa_check_context(ctx, 1 /* private key checks */,
1445 1 /* blinding on */) != 0) {
1446 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
1447 }
1448
1449 #if defined(MBEDTLS_THREADING_C)
1450 if ((ret = mbedtls_mutex_lock(&ctx->mutex)) != 0) {
1451 return ret;
1452 }
1453 #endif
1454
1455 /* MPI Initialization */
1456 mbedtls_mpi_init(&T);
1457
1458 mbedtls_mpi_init(&P1);
1459 mbedtls_mpi_init(&Q1);
1460 mbedtls_mpi_init(&R);
1461
1462 #if defined(MBEDTLS_RSA_NO_CRT)
1463 mbedtls_mpi_init(&D_blind);
1464 #else
1465 mbedtls_mpi_init(&DP_blind);
1466 mbedtls_mpi_init(&DQ_blind);
1467 #endif
1468
1469 #if !defined(MBEDTLS_RSA_NO_CRT)
1470 mbedtls_mpi_init(&TP); mbedtls_mpi_init(&TQ);
1471 #endif
1472
1473 mbedtls_mpi_init(&input_blinded);
1474 mbedtls_mpi_init(&check_result_blinded);
1475
1476 /* End of MPI initialization */
1477
1478 MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(&T, input, ctx->len));
1479 if (mbedtls_mpi_cmp_mpi(&T, &ctx->N) >= 0) {
1480 ret = MBEDTLS_ERR_MPI_BAD_INPUT_DATA;
1481 goto cleanup;
1482 }
1483
1484 /*
1485 * Blinding
1486 * T = T * Vi mod N
1487 */
1488 MBEDTLS_MPI_CHK(rsa_prepare_blinding(ctx, f_rng, p_rng));
1489 MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&T, &T, &ctx->Vi));
1490 MBEDTLS_MPI_CHK(mbedtls_mpi_mod_mpi(&T, &T, &ctx->N));
1491
1492 MBEDTLS_MPI_CHK(mbedtls_mpi_copy(&input_blinded, &T));
1493
1494 /*
1495 * Exponent blinding
1496 */
1497 MBEDTLS_MPI_CHK(mbedtls_mpi_sub_int(&P1, &ctx->P, 1));
1498 MBEDTLS_MPI_CHK(mbedtls_mpi_sub_int(&Q1, &ctx->Q, 1));
1499
1500 #if defined(MBEDTLS_RSA_NO_CRT)
1501 /*
1502 * D_blind = ( P - 1 ) * ( Q - 1 ) * R + D
1503 */
1504 MBEDTLS_MPI_CHK(mbedtls_mpi_fill_random(&R, RSA_EXPONENT_BLINDING,
1505 f_rng, p_rng));
1506 MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&D_blind, &P1, &Q1));
1507 MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&D_blind, &D_blind, &R));
1508 MBEDTLS_MPI_CHK(mbedtls_mpi_add_mpi(&D_blind, &D_blind, &ctx->D));
1509 #else
1510 /*
1511 * DP_blind = ( P - 1 ) * R + DP
1512 */
1513 MBEDTLS_MPI_CHK(mbedtls_mpi_fill_random(&R, RSA_EXPONENT_BLINDING,
1514 f_rng, p_rng));
1515 MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&DP_blind, &P1, &R));
1516 MBEDTLS_MPI_CHK(mbedtls_mpi_add_mpi(&DP_blind, &DP_blind,
1517 &ctx->DP));
1518
1519 /*
1520 * DQ_blind = ( Q - 1 ) * R + DQ
1521 */
1522 MBEDTLS_MPI_CHK(mbedtls_mpi_fill_random(&R, RSA_EXPONENT_BLINDING,
1523 f_rng, p_rng));
1524 MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&DQ_blind, &Q1, &R));
1525 MBEDTLS_MPI_CHK(mbedtls_mpi_add_mpi(&DQ_blind, &DQ_blind,
1526 &ctx->DQ));
1527 #endif /* MBEDTLS_RSA_NO_CRT */
1528
1529 #if defined(MBEDTLS_RSA_NO_CRT)
1530 MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&T, &T, &D_blind, &ctx->N, &ctx->RN));
1531 #else
1532 /*
1533 * Faster decryption using the CRT
1534 *
1535 * TP = input ^ dP mod P
1536 * TQ = input ^ dQ mod Q
1537 */
1538
1539 MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&TP, &T, &DP_blind, &ctx->P, &ctx->RP));
1540 MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&TQ, &T, &DQ_blind, &ctx->Q, &ctx->RQ));
1541
1542 /*
1543 * T = (TP - TQ) * (Q^-1 mod P) mod P
1544 */
1545 MBEDTLS_MPI_CHK(mbedtls_mpi_sub_mpi(&T, &TP, &TQ));
1546 MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&TP, &T, &ctx->QP));
1547 MBEDTLS_MPI_CHK(mbedtls_mpi_mod_mpi(&T, &TP, &ctx->P));
1548
1549 /*
1550 * T = TQ + T * Q
1551 */
1552 MBEDTLS_MPI_CHK(mbedtls_mpi_mul_mpi(&TP, &T, &ctx->Q));
1553 MBEDTLS_MPI_CHK(mbedtls_mpi_add_mpi(&T, &TQ, &TP));
1554 #endif /* MBEDTLS_RSA_NO_CRT */
1555
1556 /* Verify the result to prevent glitching attacks. */
1557 MBEDTLS_MPI_CHK(mbedtls_mpi_exp_mod(&check_result_blinded, &T, &ctx->E,
1558 &ctx->N, &ctx->RN));
1559 if (mbedtls_mpi_cmp_mpi(&check_result_blinded, &input_blinded) != 0) {
1560 ret = MBEDTLS_ERR_RSA_VERIFY_FAILED;
1561 goto cleanup;
1562 }
1563
1564 /*
1565 * Unblind
1566 * T = T * Vf mod N
1567 */
1568 MBEDTLS_MPI_CHK(rsa_unblind(&T, &ctx->Vf, &ctx->N));
1569
1570 olen = ctx->len;
1571 MBEDTLS_MPI_CHK(mbedtls_mpi_write_binary(&T, output, olen));
1572
1573 cleanup:
1574 #if defined(MBEDTLS_THREADING_C)
1575 if (mbedtls_mutex_unlock(&ctx->mutex) != 0) {
1576 return MBEDTLS_ERR_THREADING_MUTEX_ERROR;
1577 }
1578 #endif
1579
1580 mbedtls_mpi_free(&P1);
1581 mbedtls_mpi_free(&Q1);
1582 mbedtls_mpi_free(&R);
1583
1584 #if defined(MBEDTLS_RSA_NO_CRT)
1585 mbedtls_mpi_free(&D_blind);
1586 #else
1587 mbedtls_mpi_free(&DP_blind);
1588 mbedtls_mpi_free(&DQ_blind);
1589 #endif
1590
1591 mbedtls_mpi_free(&T);
1592
1593 #if !defined(MBEDTLS_RSA_NO_CRT)
1594 mbedtls_mpi_free(&TP); mbedtls_mpi_free(&TQ);
1595 #endif
1596
1597 mbedtls_mpi_free(&check_result_blinded);
1598 mbedtls_mpi_free(&input_blinded);
1599
1600 if (ret != 0 && ret >= -0x007f) {
1601 return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_RSA_PRIVATE_FAILED, ret);
1602 }
1603
1604 return ret;
1605 }
1606
1607 #if defined(MBEDTLS_PKCS1_V21)
1608 /**
1609 * Generate and apply the MGF1 operation (from PKCS#1 v2.1) to a buffer.
1610 *
1611 * \param dst buffer to mask
1612 * \param dlen length of destination buffer
1613 * \param src source of the mask generation
1614 * \param slen length of the source buffer
1615 * \param md_alg message digest to use
1616 */
mgf_mask(unsigned char * dst,size_t dlen,unsigned char * src,size_t slen,mbedtls_md_type_t md_alg)1617 static int mgf_mask(unsigned char *dst, size_t dlen, unsigned char *src,
1618 size_t slen, mbedtls_md_type_t md_alg)
1619 {
1620 unsigned char counter[4];
1621 unsigned char *p;
1622 unsigned int hlen;
1623 size_t i, use_len;
1624 unsigned char mask[MBEDTLS_MD_MAX_SIZE];
1625 int ret = 0;
1626 const mbedtls_md_info_t *md_info;
1627 mbedtls_md_context_t md_ctx;
1628
1629 mbedtls_md_init(&md_ctx);
1630 md_info = mbedtls_md_info_from_type(md_alg);
1631 if (md_info == NULL) {
1632 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
1633 }
1634
1635 mbedtls_md_init(&md_ctx);
1636 if ((ret = mbedtls_md_setup(&md_ctx, md_info, 0)) != 0) {
1637 goto exit;
1638 }
1639
1640 hlen = mbedtls_md_get_size(md_info);
1641
1642 memset(mask, 0, sizeof(mask));
1643 memset(counter, 0, 4);
1644
1645 /* Generate and apply dbMask */
1646 p = dst;
1647
1648 while (dlen > 0) {
1649 use_len = hlen;
1650 if (dlen < hlen) {
1651 use_len = dlen;
1652 }
1653
1654 if ((ret = mbedtls_md_starts(&md_ctx)) != 0) {
1655 goto exit;
1656 }
1657 if ((ret = mbedtls_md_update(&md_ctx, src, slen)) != 0) {
1658 goto exit;
1659 }
1660 if ((ret = mbedtls_md_update(&md_ctx, counter, 4)) != 0) {
1661 goto exit;
1662 }
1663 if ((ret = mbedtls_md_finish(&md_ctx, mask)) != 0) {
1664 goto exit;
1665 }
1666
1667 for (i = 0; i < use_len; ++i) {
1668 *p++ ^= mask[i];
1669 }
1670
1671 counter[3]++;
1672
1673 dlen -= use_len;
1674 }
1675
1676 exit:
1677 mbedtls_platform_zeroize(mask, sizeof(mask));
1678 mbedtls_md_free(&md_ctx);
1679
1680 return ret;
1681 }
1682
1683 /**
1684 * Generate Hash(M') as in RFC 8017 page 43 points 5 and 6.
1685 *
1686 * \param hash the input hash
1687 * \param hlen length of the input hash
1688 * \param salt the input salt
1689 * \param slen length of the input salt
1690 * \param out the output buffer - must be large enough for \p md_alg
1691 * \param md_alg message digest to use
1692 */
hash_mprime(const unsigned char * hash,size_t hlen,const unsigned char * salt,size_t slen,unsigned char * out,mbedtls_md_type_t md_alg)1693 static int hash_mprime(const unsigned char *hash, size_t hlen,
1694 const unsigned char *salt, size_t slen,
1695 unsigned char *out, mbedtls_md_type_t md_alg)
1696 {
1697 const unsigned char zeros[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
1698
1699 mbedtls_md_context_t md_ctx;
1700 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
1701
1702 const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type(md_alg);
1703 if (md_info == NULL) {
1704 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
1705 }
1706
1707 mbedtls_md_init(&md_ctx);
1708 if ((ret = mbedtls_md_setup(&md_ctx, md_info, 0)) != 0) {
1709 goto exit;
1710 }
1711 if ((ret = mbedtls_md_starts(&md_ctx)) != 0) {
1712 goto exit;
1713 }
1714 if ((ret = mbedtls_md_update(&md_ctx, zeros, sizeof(zeros))) != 0) {
1715 goto exit;
1716 }
1717 if ((ret = mbedtls_md_update(&md_ctx, hash, hlen)) != 0) {
1718 goto exit;
1719 }
1720 if ((ret = mbedtls_md_update(&md_ctx, salt, slen)) != 0) {
1721 goto exit;
1722 }
1723 if ((ret = mbedtls_md_finish(&md_ctx, out)) != 0) {
1724 goto exit;
1725 }
1726
1727 exit:
1728 mbedtls_md_free(&md_ctx);
1729
1730 return ret;
1731 }
1732
1733 /**
1734 * Compute a hash.
1735 *
1736 * \param md_alg algorithm to use
1737 * \param input input message to hash
1738 * \param ilen input length
1739 * \param output the output buffer - must be large enough for \p md_alg
1740 */
compute_hash(mbedtls_md_type_t md_alg,const unsigned char * input,size_t ilen,unsigned char * output)1741 static int compute_hash(mbedtls_md_type_t md_alg,
1742 const unsigned char *input, size_t ilen,
1743 unsigned char *output)
1744 {
1745 const mbedtls_md_info_t *md_info;
1746
1747 md_info = mbedtls_md_info_from_type(md_alg);
1748 if (md_info == NULL) {
1749 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
1750 }
1751
1752 return mbedtls_md(md_info, input, ilen, output);
1753 }
1754 #endif /* MBEDTLS_PKCS1_V21 */
1755
1756 #if defined(MBEDTLS_PKCS1_V21)
1757 /*
1758 * Implementation of the PKCS#1 v2.1 RSAES-OAEP-ENCRYPT function
1759 */
mbedtls_rsa_rsaes_oaep_encrypt(mbedtls_rsa_context * ctx,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng,const unsigned char * label,size_t label_len,size_t ilen,const unsigned char * input,unsigned char * output)1760 int mbedtls_rsa_rsaes_oaep_encrypt(mbedtls_rsa_context *ctx,
1761 int (*f_rng)(void *, unsigned char *, size_t),
1762 void *p_rng,
1763 const unsigned char *label, size_t label_len,
1764 size_t ilen,
1765 const unsigned char *input,
1766 unsigned char *output)
1767 {
1768 size_t olen;
1769 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
1770 unsigned char *p = output;
1771 unsigned int hlen;
1772
1773 if (f_rng == NULL) {
1774 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
1775 }
1776
1777 hlen = mbedtls_md_get_size_from_type((mbedtls_md_type_t) ctx->hash_id);
1778 if (hlen == 0) {
1779 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
1780 }
1781
1782 olen = ctx->len;
1783
1784 /* first comparison checks for overflow */
1785 if (ilen + 2 * hlen + 2 < ilen || olen < ilen + 2 * hlen + 2) {
1786 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
1787 }
1788
1789 memset(output, 0, olen);
1790
1791 *p++ = 0;
1792
1793 /* Generate a random octet string seed */
1794 if ((ret = f_rng(p_rng, p, hlen)) != 0) {
1795 return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_RSA_RNG_FAILED, ret);
1796 }
1797
1798 p += hlen;
1799
1800 /* Construct DB */
1801 ret = compute_hash((mbedtls_md_type_t) ctx->hash_id, label, label_len, p);
1802 if (ret != 0) {
1803 return ret;
1804 }
1805 p += hlen;
1806 p += olen - 2 * hlen - 2 - ilen;
1807 *p++ = 1;
1808 if (ilen != 0) {
1809 memcpy(p, input, ilen);
1810 }
1811
1812 /* maskedDB: Apply dbMask to DB */
1813 if ((ret = mgf_mask(output + hlen + 1, olen - hlen - 1, output + 1, hlen,
1814 (mbedtls_md_type_t) ctx->hash_id)) != 0) {
1815 return ret;
1816 }
1817
1818 /* maskedSeed: Apply seedMask to seed */
1819 if ((ret = mgf_mask(output + 1, hlen, output + hlen + 1, olen - hlen - 1,
1820 (mbedtls_md_type_t) ctx->hash_id)) != 0) {
1821 return ret;
1822 }
1823
1824 return mbedtls_rsa_public(ctx, output, output);
1825 }
1826 #endif /* MBEDTLS_PKCS1_V21 */
1827
1828 #if defined(MBEDTLS_PKCS1_V15)
1829 /*
1830 * Implementation of the PKCS#1 v2.1 RSAES-PKCS1-V1_5-ENCRYPT function
1831 */
mbedtls_rsa_rsaes_pkcs1_v15_encrypt(mbedtls_rsa_context * ctx,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng,size_t ilen,const unsigned char * input,unsigned char * output)1832 int mbedtls_rsa_rsaes_pkcs1_v15_encrypt(mbedtls_rsa_context *ctx,
1833 int (*f_rng)(void *, unsigned char *, size_t),
1834 void *p_rng, size_t ilen,
1835 const unsigned char *input,
1836 unsigned char *output)
1837 {
1838 size_t nb_pad, olen;
1839 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
1840 unsigned char *p = output;
1841
1842 olen = ctx->len;
1843
1844 /* first comparison checks for overflow */
1845 if (ilen + 11 < ilen || olen < ilen + 11) {
1846 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
1847 }
1848
1849 nb_pad = olen - 3 - ilen;
1850
1851 *p++ = 0;
1852
1853 if (f_rng == NULL) {
1854 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
1855 }
1856
1857 *p++ = MBEDTLS_RSA_CRYPT;
1858
1859 while (nb_pad-- > 0) {
1860 int rng_dl = 100;
1861
1862 do {
1863 ret = f_rng(p_rng, p, 1);
1864 } while (*p == 0 && --rng_dl && ret == 0);
1865
1866 /* Check if RNG failed to generate data */
1867 if (rng_dl == 0 || ret != 0) {
1868 return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_RSA_RNG_FAILED, ret);
1869 }
1870
1871 p++;
1872 }
1873
1874 *p++ = 0;
1875 if (ilen != 0) {
1876 memcpy(p, input, ilen);
1877 }
1878
1879 return mbedtls_rsa_public(ctx, output, output);
1880 }
1881 #endif /* MBEDTLS_PKCS1_V15 */
1882
1883 /*
1884 * Add the message padding, then do an RSA operation
1885 */
mbedtls_rsa_pkcs1_encrypt(mbedtls_rsa_context * ctx,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng,size_t ilen,const unsigned char * input,unsigned char * output)1886 int mbedtls_rsa_pkcs1_encrypt(mbedtls_rsa_context *ctx,
1887 int (*f_rng)(void *, unsigned char *, size_t),
1888 void *p_rng,
1889 size_t ilen,
1890 const unsigned char *input,
1891 unsigned char *output)
1892 {
1893 switch (ctx->padding) {
1894 #if defined(MBEDTLS_PKCS1_V15)
1895 case MBEDTLS_RSA_PKCS_V15:
1896 return mbedtls_rsa_rsaes_pkcs1_v15_encrypt(ctx, f_rng, p_rng,
1897 ilen, input, output);
1898 #endif
1899
1900 #if defined(MBEDTLS_PKCS1_V21)
1901 case MBEDTLS_RSA_PKCS_V21:
1902 return mbedtls_rsa_rsaes_oaep_encrypt(ctx, f_rng, p_rng, NULL, 0,
1903 ilen, input, output);
1904 #endif
1905
1906 default:
1907 return MBEDTLS_ERR_RSA_INVALID_PADDING;
1908 }
1909 }
1910
1911 #if defined(MBEDTLS_PKCS1_V21)
1912 /*
1913 * Implementation of the PKCS#1 v2.1 RSAES-OAEP-DECRYPT function
1914 */
mbedtls_rsa_rsaes_oaep_decrypt(mbedtls_rsa_context * ctx,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng,const unsigned char * label,size_t label_len,size_t * olen,const unsigned char * input,unsigned char * output,size_t output_max_len)1915 int mbedtls_rsa_rsaes_oaep_decrypt(mbedtls_rsa_context *ctx,
1916 int (*f_rng)(void *, unsigned char *, size_t),
1917 void *p_rng,
1918 const unsigned char *label, size_t label_len,
1919 size_t *olen,
1920 const unsigned char *input,
1921 unsigned char *output,
1922 size_t output_max_len)
1923 {
1924 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
1925 size_t ilen, i, pad_len;
1926 unsigned char *p;
1927 mbedtls_ct_condition_t bad, in_padding;
1928 unsigned char buf[MBEDTLS_MPI_MAX_SIZE];
1929 unsigned char lhash[MBEDTLS_MD_MAX_SIZE];
1930 unsigned int hlen;
1931
1932 /*
1933 * Parameters sanity checks
1934 */
1935 if (ctx->padding != MBEDTLS_RSA_PKCS_V21) {
1936 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
1937 }
1938
1939 ilen = ctx->len;
1940
1941 if (ilen < 16 || ilen > sizeof(buf)) {
1942 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
1943 }
1944
1945 hlen = mbedtls_md_get_size_from_type((mbedtls_md_type_t) ctx->hash_id);
1946 if (hlen == 0) {
1947 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
1948 }
1949
1950 // checking for integer underflow
1951 if (2 * hlen + 2 > ilen) {
1952 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
1953 }
1954
1955 /*
1956 * RSA operation
1957 */
1958 ret = mbedtls_rsa_private(ctx, f_rng, p_rng, input, buf);
1959
1960 if (ret != 0) {
1961 goto cleanup;
1962 }
1963
1964 /*
1965 * Unmask data and generate lHash
1966 */
1967 /* seed: Apply seedMask to maskedSeed */
1968 if ((ret = mgf_mask(buf + 1, hlen, buf + hlen + 1, ilen - hlen - 1,
1969 (mbedtls_md_type_t) ctx->hash_id)) != 0 ||
1970 /* DB: Apply dbMask to maskedDB */
1971 (ret = mgf_mask(buf + hlen + 1, ilen - hlen - 1, buf + 1, hlen,
1972 (mbedtls_md_type_t) ctx->hash_id)) != 0) {
1973 goto cleanup;
1974 }
1975
1976 /* Generate lHash */
1977 ret = compute_hash((mbedtls_md_type_t) ctx->hash_id,
1978 label, label_len, lhash);
1979 if (ret != 0) {
1980 goto cleanup;
1981 }
1982
1983 /*
1984 * Check contents, in "constant-time"
1985 */
1986 p = buf;
1987
1988 bad = mbedtls_ct_bool(*p++); /* First byte must be 0 */
1989
1990 p += hlen; /* Skip seed */
1991
1992 /* Check lHash */
1993 bad = mbedtls_ct_bool_or(bad, mbedtls_ct_bool(mbedtls_ct_memcmp(lhash, p, hlen)));
1994 p += hlen;
1995
1996 /* Get zero-padding len, but always read till end of buffer
1997 * (minus one, for the 01 byte) */
1998 pad_len = 0;
1999 in_padding = MBEDTLS_CT_TRUE;
2000 for (i = 0; i < ilen - 2 * hlen - 2; i++) {
2001 in_padding = mbedtls_ct_bool_and(in_padding, mbedtls_ct_uint_eq(p[i], 0));
2002 pad_len += mbedtls_ct_uint_if_else_0(in_padding, 1);
2003 }
2004
2005 p += pad_len;
2006 bad = mbedtls_ct_bool_or(bad, mbedtls_ct_uint_ne(*p++, 0x01));
2007
2008 /*
2009 * The only information "leaked" is whether the padding was correct or not
2010 * (eg, no data is copied if it was not correct). This meets the
2011 * recommendations in PKCS#1 v2.2: an opponent cannot distinguish between
2012 * the different error conditions.
2013 */
2014 if (bad != MBEDTLS_CT_FALSE) {
2015 ret = MBEDTLS_ERR_RSA_INVALID_PADDING;
2016 goto cleanup;
2017 }
2018
2019 if (ilen - ((size_t) (p - buf)) > output_max_len) {
2020 ret = MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE;
2021 goto cleanup;
2022 }
2023
2024 *olen = ilen - ((size_t) (p - buf));
2025 if (*olen != 0) {
2026 memcpy(output, p, *olen);
2027 }
2028 ret = 0;
2029
2030 cleanup:
2031 mbedtls_platform_zeroize(buf, sizeof(buf));
2032 mbedtls_platform_zeroize(lhash, sizeof(lhash));
2033
2034 return ret;
2035 }
2036 #endif /* MBEDTLS_PKCS1_V21 */
2037
2038 #if defined(MBEDTLS_PKCS1_V15)
2039 /*
2040 * Implementation of the PKCS#1 v2.1 RSAES-PKCS1-V1_5-DECRYPT function
2041 */
mbedtls_rsa_rsaes_pkcs1_v15_decrypt(mbedtls_rsa_context * ctx,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng,size_t * olen,const unsigned char * input,unsigned char * output,size_t output_max_len)2042 int mbedtls_rsa_rsaes_pkcs1_v15_decrypt(mbedtls_rsa_context *ctx,
2043 int (*f_rng)(void *, unsigned char *, size_t),
2044 void *p_rng,
2045 size_t *olen,
2046 const unsigned char *input,
2047 unsigned char *output,
2048 size_t output_max_len)
2049 {
2050 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
2051 size_t ilen;
2052 unsigned char buf[MBEDTLS_MPI_MAX_SIZE];
2053
2054 ilen = ctx->len;
2055
2056 if (ctx->padding != MBEDTLS_RSA_PKCS_V15) {
2057 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2058 }
2059
2060 if (ilen < 16 || ilen > sizeof(buf)) {
2061 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2062 }
2063
2064 ret = mbedtls_rsa_private(ctx, f_rng, p_rng, input, buf);
2065
2066 if (ret != 0) {
2067 goto cleanup;
2068 }
2069
2070 ret = mbedtls_ct_rsaes_pkcs1_v15_unpadding(buf, ilen,
2071 output, output_max_len, olen);
2072
2073 cleanup:
2074 mbedtls_platform_zeroize(buf, sizeof(buf));
2075
2076 return ret;
2077 }
2078 #endif /* MBEDTLS_PKCS1_V15 */
2079
2080 /*
2081 * Do an RSA operation, then remove the message padding
2082 */
mbedtls_rsa_pkcs1_decrypt(mbedtls_rsa_context * ctx,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng,size_t * olen,const unsigned char * input,unsigned char * output,size_t output_max_len)2083 int mbedtls_rsa_pkcs1_decrypt(mbedtls_rsa_context *ctx,
2084 int (*f_rng)(void *, unsigned char *, size_t),
2085 void *p_rng,
2086 size_t *olen,
2087 const unsigned char *input,
2088 unsigned char *output,
2089 size_t output_max_len)
2090 {
2091 switch (ctx->padding) {
2092 #if defined(MBEDTLS_PKCS1_V15)
2093 case MBEDTLS_RSA_PKCS_V15:
2094 return mbedtls_rsa_rsaes_pkcs1_v15_decrypt(ctx, f_rng, p_rng, olen,
2095 input, output, output_max_len);
2096 #endif
2097
2098 #if defined(MBEDTLS_PKCS1_V21)
2099 case MBEDTLS_RSA_PKCS_V21:
2100 return mbedtls_rsa_rsaes_oaep_decrypt(ctx, f_rng, p_rng, NULL, 0,
2101 olen, input, output,
2102 output_max_len);
2103 #endif
2104
2105 default:
2106 return MBEDTLS_ERR_RSA_INVALID_PADDING;
2107 }
2108 }
2109
2110 #if defined(MBEDTLS_PKCS1_V21)
rsa_rsassa_pss_sign_no_mode_check(mbedtls_rsa_context * ctx,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng,mbedtls_md_type_t md_alg,unsigned int hashlen,const unsigned char * hash,int saltlen,unsigned char * sig)2111 static int rsa_rsassa_pss_sign_no_mode_check(mbedtls_rsa_context *ctx,
2112 int (*f_rng)(void *, unsigned char *, size_t),
2113 void *p_rng,
2114 mbedtls_md_type_t md_alg,
2115 unsigned int hashlen,
2116 const unsigned char *hash,
2117 int saltlen,
2118 unsigned char *sig)
2119 {
2120 size_t olen;
2121 unsigned char *p = sig;
2122 unsigned char *salt = NULL;
2123 size_t slen, min_slen, hlen, offset = 0;
2124 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
2125 size_t msb;
2126 mbedtls_md_type_t hash_id;
2127
2128 if ((md_alg != MBEDTLS_MD_NONE || hashlen != 0) && hash == NULL) {
2129 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2130 }
2131
2132 if (f_rng == NULL) {
2133 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2134 }
2135
2136 olen = ctx->len;
2137
2138 if (md_alg != MBEDTLS_MD_NONE) {
2139 /* Gather length of hash to sign */
2140 size_t exp_hashlen = mbedtls_md_get_size_from_type(md_alg);
2141 if (exp_hashlen == 0) {
2142 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2143 }
2144
2145 if (hashlen != exp_hashlen) {
2146 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2147 }
2148 }
2149
2150 hash_id = (mbedtls_md_type_t) ctx->hash_id;
2151 if (hash_id == MBEDTLS_MD_NONE) {
2152 hash_id = md_alg;
2153 }
2154 hlen = mbedtls_md_get_size_from_type(hash_id);
2155 if (hlen == 0) {
2156 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2157 }
2158
2159 if (saltlen == MBEDTLS_RSA_SALT_LEN_ANY) {
2160 /* Calculate the largest possible salt length, up to the hash size.
2161 * Normally this is the hash length, which is the maximum salt length
2162 * according to FIPS 185-4 §5.5 (e) and common practice. If there is not
2163 * enough room, use the maximum salt length that fits. The constraint is
2164 * that the hash length plus the salt length plus 2 bytes must be at most
2165 * the key length. This complies with FIPS 186-4 §5.5 (e) and RFC 8017
2166 * (PKCS#1 v2.2) §9.1.1 step 3. */
2167 min_slen = hlen - 2;
2168 if (olen < hlen + min_slen + 2) {
2169 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2170 } else if (olen >= hlen + hlen + 2) {
2171 slen = hlen;
2172 } else {
2173 slen = olen - hlen - 2;
2174 }
2175 } else if ((saltlen < 0) || (saltlen + hlen + 2 > olen)) {
2176 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2177 } else {
2178 slen = (size_t) saltlen;
2179 }
2180
2181 memset(sig, 0, olen);
2182
2183 /* Note: EMSA-PSS encoding is over the length of N - 1 bits */
2184 msb = mbedtls_mpi_bitlen(&ctx->N) - 1;
2185 p += olen - hlen - slen - 2;
2186 *p++ = 0x01;
2187
2188 /* Generate salt of length slen in place in the encoded message */
2189 salt = p;
2190 if ((ret = f_rng(p_rng, salt, slen)) != 0) {
2191 return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_RSA_RNG_FAILED, ret);
2192 }
2193
2194 p += slen;
2195
2196 /* Generate H = Hash( M' ) */
2197 ret = hash_mprime(hash, hashlen, salt, slen, p, hash_id);
2198 if (ret != 0) {
2199 return ret;
2200 }
2201
2202 /* Compensate for boundary condition when applying mask */
2203 if (msb % 8 == 0) {
2204 offset = 1;
2205 }
2206
2207 /* maskedDB: Apply dbMask to DB */
2208 ret = mgf_mask(sig + offset, olen - hlen - 1 - offset, p, hlen, hash_id);
2209 if (ret != 0) {
2210 return ret;
2211 }
2212
2213 msb = mbedtls_mpi_bitlen(&ctx->N) - 1;
2214 sig[0] &= 0xFF >> (olen * 8 - msb);
2215
2216 p += hlen;
2217 *p++ = 0xBC;
2218
2219 return mbedtls_rsa_private(ctx, f_rng, p_rng, sig, sig);
2220 }
2221
rsa_rsassa_pss_sign(mbedtls_rsa_context * ctx,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng,mbedtls_md_type_t md_alg,unsigned int hashlen,const unsigned char * hash,int saltlen,unsigned char * sig)2222 static int rsa_rsassa_pss_sign(mbedtls_rsa_context *ctx,
2223 int (*f_rng)(void *, unsigned char *, size_t),
2224 void *p_rng,
2225 mbedtls_md_type_t md_alg,
2226 unsigned int hashlen,
2227 const unsigned char *hash,
2228 int saltlen,
2229 unsigned char *sig)
2230 {
2231 if (ctx->padding != MBEDTLS_RSA_PKCS_V21) {
2232 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2233 }
2234 if ((ctx->hash_id == MBEDTLS_MD_NONE) && (md_alg == MBEDTLS_MD_NONE)) {
2235 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2236 }
2237 return rsa_rsassa_pss_sign_no_mode_check(ctx, f_rng, p_rng, md_alg, hashlen, hash, saltlen,
2238 sig);
2239 }
2240
mbedtls_rsa_rsassa_pss_sign_no_mode_check(mbedtls_rsa_context * ctx,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng,mbedtls_md_type_t md_alg,unsigned int hashlen,const unsigned char * hash,unsigned char * sig)2241 int mbedtls_rsa_rsassa_pss_sign_no_mode_check(mbedtls_rsa_context *ctx,
2242 int (*f_rng)(void *, unsigned char *, size_t),
2243 void *p_rng,
2244 mbedtls_md_type_t md_alg,
2245 unsigned int hashlen,
2246 const unsigned char *hash,
2247 unsigned char *sig)
2248 {
2249 return rsa_rsassa_pss_sign_no_mode_check(ctx, f_rng, p_rng, md_alg,
2250 hashlen, hash, MBEDTLS_RSA_SALT_LEN_ANY, sig);
2251 }
2252
2253 /*
2254 * Implementation of the PKCS#1 v2.1 RSASSA-PSS-SIGN function with
2255 * the option to pass in the salt length.
2256 */
mbedtls_rsa_rsassa_pss_sign_ext(mbedtls_rsa_context * ctx,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng,mbedtls_md_type_t md_alg,unsigned int hashlen,const unsigned char * hash,int saltlen,unsigned char * sig)2257 int mbedtls_rsa_rsassa_pss_sign_ext(mbedtls_rsa_context *ctx,
2258 int (*f_rng)(void *, unsigned char *, size_t),
2259 void *p_rng,
2260 mbedtls_md_type_t md_alg,
2261 unsigned int hashlen,
2262 const unsigned char *hash,
2263 int saltlen,
2264 unsigned char *sig)
2265 {
2266 return rsa_rsassa_pss_sign(ctx, f_rng, p_rng, md_alg,
2267 hashlen, hash, saltlen, sig);
2268 }
2269
2270 /*
2271 * Implementation of the PKCS#1 v2.1 RSASSA-PSS-SIGN function
2272 */
mbedtls_rsa_rsassa_pss_sign(mbedtls_rsa_context * ctx,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng,mbedtls_md_type_t md_alg,unsigned int hashlen,const unsigned char * hash,unsigned char * sig)2273 int mbedtls_rsa_rsassa_pss_sign(mbedtls_rsa_context *ctx,
2274 int (*f_rng)(void *, unsigned char *, size_t),
2275 void *p_rng,
2276 mbedtls_md_type_t md_alg,
2277 unsigned int hashlen,
2278 const unsigned char *hash,
2279 unsigned char *sig)
2280 {
2281 return rsa_rsassa_pss_sign(ctx, f_rng, p_rng, md_alg,
2282 hashlen, hash, MBEDTLS_RSA_SALT_LEN_ANY, sig);
2283 }
2284 #endif /* MBEDTLS_PKCS1_V21 */
2285
2286 #if defined(MBEDTLS_PKCS1_V15)
2287 /*
2288 * Implementation of the PKCS#1 v2.1 RSASSA-PKCS1-V1_5-SIGN function
2289 */
2290
2291 /* Construct a PKCS v1.5 encoding of a hashed message
2292 *
2293 * This is used both for signature generation and verification.
2294 *
2295 * Parameters:
2296 * - md_alg: Identifies the hash algorithm used to generate the given hash;
2297 * MBEDTLS_MD_NONE if raw data is signed.
2298 * - hashlen: Length of hash. Must match md_alg if that's not NONE.
2299 * - hash: Buffer containing the hashed message or the raw data.
2300 * - dst_len: Length of the encoded message.
2301 * - dst: Buffer to hold the encoded message.
2302 *
2303 * Assumptions:
2304 * - hash has size hashlen.
2305 * - dst points to a buffer of size at least dst_len.
2306 *
2307 */
rsa_rsassa_pkcs1_v15_encode(mbedtls_md_type_t md_alg,unsigned int hashlen,const unsigned char * hash,size_t dst_len,unsigned char * dst)2308 static int rsa_rsassa_pkcs1_v15_encode(mbedtls_md_type_t md_alg,
2309 unsigned int hashlen,
2310 const unsigned char *hash,
2311 size_t dst_len,
2312 unsigned char *dst)
2313 {
2314 size_t oid_size = 0;
2315 size_t nb_pad = dst_len;
2316 unsigned char *p = dst;
2317 const char *oid = NULL;
2318
2319 /* Are we signing hashed or raw data? */
2320 if (md_alg != MBEDTLS_MD_NONE) {
2321 unsigned char md_size = mbedtls_md_get_size_from_type(md_alg);
2322 if (md_size == 0) {
2323 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2324 }
2325
2326 if (mbedtls_oid_get_oid_by_md(md_alg, &oid, &oid_size) != 0) {
2327 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2328 }
2329
2330 if (hashlen != md_size) {
2331 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2332 }
2333
2334 /* Double-check that 8 + hashlen + oid_size can be used as a
2335 * 1-byte ASN.1 length encoding and that there's no overflow. */
2336 if (8 + hashlen + oid_size >= 0x80 ||
2337 10 + hashlen < hashlen ||
2338 10 + hashlen + oid_size < 10 + hashlen) {
2339 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2340 }
2341
2342 /*
2343 * Static bounds check:
2344 * - Need 10 bytes for five tag-length pairs.
2345 * (Insist on 1-byte length encodings to protect against variants of
2346 * Bleichenbacher's forgery attack against lax PKCS#1v1.5 verification)
2347 * - Need hashlen bytes for hash
2348 * - Need oid_size bytes for hash alg OID.
2349 */
2350 if (nb_pad < 10 + hashlen + oid_size) {
2351 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2352 }
2353 nb_pad -= 10 + hashlen + oid_size;
2354 } else {
2355 if (nb_pad < hashlen) {
2356 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2357 }
2358
2359 nb_pad -= hashlen;
2360 }
2361
2362 /* Need space for signature header and padding delimiter (3 bytes),
2363 * and 8 bytes for the minimal padding */
2364 if (nb_pad < 3 + 8) {
2365 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2366 }
2367 nb_pad -= 3;
2368
2369 /* Now nb_pad is the amount of memory to be filled
2370 * with padding, and at least 8 bytes long. */
2371
2372 /* Write signature header and padding */
2373 *p++ = 0;
2374 *p++ = MBEDTLS_RSA_SIGN;
2375 memset(p, 0xFF, nb_pad);
2376 p += nb_pad;
2377 *p++ = 0;
2378
2379 /* Are we signing raw data? */
2380 if (md_alg == MBEDTLS_MD_NONE) {
2381 memcpy(p, hash, hashlen);
2382 return 0;
2383 }
2384
2385 /* Signing hashed data, add corresponding ASN.1 structure
2386 *
2387 * DigestInfo ::= SEQUENCE {
2388 * digestAlgorithm DigestAlgorithmIdentifier,
2389 * digest Digest }
2390 * DigestAlgorithmIdentifier ::= AlgorithmIdentifier
2391 * Digest ::= OCTET STRING
2392 *
2393 * Schematic:
2394 * TAG-SEQ + LEN [ TAG-SEQ + LEN [ TAG-OID + LEN [ OID ]
2395 * TAG-NULL + LEN [ NULL ] ]
2396 * TAG-OCTET + LEN [ HASH ] ]
2397 */
2398 *p++ = MBEDTLS_ASN1_SEQUENCE | MBEDTLS_ASN1_CONSTRUCTED;
2399 *p++ = (unsigned char) (0x08 + oid_size + hashlen);
2400 *p++ = MBEDTLS_ASN1_SEQUENCE | MBEDTLS_ASN1_CONSTRUCTED;
2401 *p++ = (unsigned char) (0x04 + oid_size);
2402 *p++ = MBEDTLS_ASN1_OID;
2403 *p++ = (unsigned char) oid_size;
2404 memcpy(p, oid, oid_size);
2405 p += oid_size;
2406 *p++ = MBEDTLS_ASN1_NULL;
2407 *p++ = 0x00;
2408 *p++ = MBEDTLS_ASN1_OCTET_STRING;
2409 *p++ = (unsigned char) hashlen;
2410 memcpy(p, hash, hashlen);
2411 p += hashlen;
2412
2413 /* Just a sanity-check, should be automatic
2414 * after the initial bounds check. */
2415 if (p != dst + dst_len) {
2416 mbedtls_platform_zeroize(dst, dst_len);
2417 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2418 }
2419
2420 return 0;
2421 }
2422
2423 /*
2424 * Do an RSA operation to sign the message digest
2425 */
mbedtls_rsa_rsassa_pkcs1_v15_sign(mbedtls_rsa_context * ctx,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng,mbedtls_md_type_t md_alg,unsigned int hashlen,const unsigned char * hash,unsigned char * sig)2426 int mbedtls_rsa_rsassa_pkcs1_v15_sign(mbedtls_rsa_context *ctx,
2427 int (*f_rng)(void *, unsigned char *, size_t),
2428 void *p_rng,
2429 mbedtls_md_type_t md_alg,
2430 unsigned int hashlen,
2431 const unsigned char *hash,
2432 unsigned char *sig)
2433 {
2434 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
2435 unsigned char *sig_try = NULL, *verif = NULL;
2436
2437 if ((md_alg != MBEDTLS_MD_NONE || hashlen != 0) && hash == NULL) {
2438 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2439 }
2440
2441 if (ctx->padding != MBEDTLS_RSA_PKCS_V15) {
2442 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2443 }
2444
2445 /*
2446 * Prepare PKCS1-v1.5 encoding (padding and hash identifier)
2447 */
2448
2449 if ((ret = rsa_rsassa_pkcs1_v15_encode(md_alg, hashlen, hash,
2450 ctx->len, sig)) != 0) {
2451 return ret;
2452 }
2453
2454 /* Private key operation
2455 *
2456 * In order to prevent Lenstra's attack, make the signature in a
2457 * temporary buffer and check it before returning it.
2458 */
2459
2460 sig_try = mbedtls_calloc(1, ctx->len);
2461 if (sig_try == NULL) {
2462 return MBEDTLS_ERR_MPI_ALLOC_FAILED;
2463 }
2464
2465 verif = mbedtls_calloc(1, ctx->len);
2466 if (verif == NULL) {
2467 mbedtls_free(sig_try);
2468 return MBEDTLS_ERR_MPI_ALLOC_FAILED;
2469 }
2470
2471 MBEDTLS_MPI_CHK(mbedtls_rsa_private(ctx, f_rng, p_rng, sig, sig_try));
2472 MBEDTLS_MPI_CHK(mbedtls_rsa_public(ctx, sig_try, verif));
2473
2474 if (mbedtls_ct_memcmp(verif, sig, ctx->len) != 0) {
2475 ret = MBEDTLS_ERR_RSA_PRIVATE_FAILED;
2476 goto cleanup;
2477 }
2478
2479 memcpy(sig, sig_try, ctx->len);
2480
2481 cleanup:
2482 mbedtls_zeroize_and_free(sig_try, ctx->len);
2483 mbedtls_zeroize_and_free(verif, ctx->len);
2484
2485 if (ret != 0) {
2486 memset(sig, '!', ctx->len);
2487 }
2488 return ret;
2489 }
2490 #endif /* MBEDTLS_PKCS1_V15 */
2491
2492 /*
2493 * Do an RSA operation to sign the message digest
2494 */
mbedtls_rsa_pkcs1_sign(mbedtls_rsa_context * ctx,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng,mbedtls_md_type_t md_alg,unsigned int hashlen,const unsigned char * hash,unsigned char * sig)2495 int mbedtls_rsa_pkcs1_sign(mbedtls_rsa_context *ctx,
2496 int (*f_rng)(void *, unsigned char *, size_t),
2497 void *p_rng,
2498 mbedtls_md_type_t md_alg,
2499 unsigned int hashlen,
2500 const unsigned char *hash,
2501 unsigned char *sig)
2502 {
2503 if ((md_alg != MBEDTLS_MD_NONE || hashlen != 0) && hash == NULL) {
2504 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2505 }
2506
2507 switch (ctx->padding) {
2508 #if defined(MBEDTLS_PKCS1_V15)
2509 case MBEDTLS_RSA_PKCS_V15:
2510 return mbedtls_rsa_rsassa_pkcs1_v15_sign(ctx, f_rng, p_rng,
2511 md_alg, hashlen, hash, sig);
2512 #endif
2513
2514 #if defined(MBEDTLS_PKCS1_V21)
2515 case MBEDTLS_RSA_PKCS_V21:
2516 return mbedtls_rsa_rsassa_pss_sign(ctx, f_rng, p_rng, md_alg,
2517 hashlen, hash, sig);
2518 #endif
2519
2520 default:
2521 return MBEDTLS_ERR_RSA_INVALID_PADDING;
2522 }
2523 }
2524
2525 #if defined(MBEDTLS_PKCS1_V21)
2526 /*
2527 * Implementation of the PKCS#1 v2.1 RSASSA-PSS-VERIFY function
2528 */
mbedtls_rsa_rsassa_pss_verify_ext(mbedtls_rsa_context * ctx,mbedtls_md_type_t md_alg,unsigned int hashlen,const unsigned char * hash,mbedtls_md_type_t mgf1_hash_id,int expected_salt_len,const unsigned char * sig)2529 int mbedtls_rsa_rsassa_pss_verify_ext(mbedtls_rsa_context *ctx,
2530 mbedtls_md_type_t md_alg,
2531 unsigned int hashlen,
2532 const unsigned char *hash,
2533 mbedtls_md_type_t mgf1_hash_id,
2534 int expected_salt_len,
2535 const unsigned char *sig)
2536 {
2537 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
2538 size_t siglen;
2539 unsigned char *p;
2540 unsigned char *hash_start;
2541 unsigned char result[MBEDTLS_MD_MAX_SIZE];
2542 unsigned int hlen;
2543 size_t observed_salt_len, msb;
2544 unsigned char buf[MBEDTLS_MPI_MAX_SIZE] = { 0 };
2545
2546 if ((md_alg != MBEDTLS_MD_NONE || hashlen != 0) && hash == NULL) {
2547 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2548 }
2549
2550 siglen = ctx->len;
2551
2552 if (siglen < 16 || siglen > sizeof(buf)) {
2553 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2554 }
2555
2556 ret = mbedtls_rsa_public(ctx, sig, buf);
2557
2558 if (ret != 0) {
2559 return ret;
2560 }
2561
2562 p = buf;
2563
2564 if (buf[siglen - 1] != 0xBC) {
2565 return MBEDTLS_ERR_RSA_INVALID_PADDING;
2566 }
2567
2568 if (md_alg != MBEDTLS_MD_NONE) {
2569 /* Gather length of hash to sign */
2570 size_t exp_hashlen = mbedtls_md_get_size_from_type(md_alg);
2571 if (exp_hashlen == 0) {
2572 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2573 }
2574
2575 if (hashlen != exp_hashlen) {
2576 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2577 }
2578 }
2579
2580 hlen = mbedtls_md_get_size_from_type(mgf1_hash_id);
2581 if (hlen == 0) {
2582 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2583 }
2584
2585 /*
2586 * Note: EMSA-PSS verification is over the length of N - 1 bits
2587 */
2588 msb = mbedtls_mpi_bitlen(&ctx->N) - 1;
2589
2590 if (buf[0] >> (8 - siglen * 8 + msb)) {
2591 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2592 }
2593
2594 /* Compensate for boundary condition when applying mask */
2595 if (msb % 8 == 0) {
2596 p++;
2597 siglen -= 1;
2598 }
2599
2600 if (siglen < hlen + 2) {
2601 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2602 }
2603 hash_start = p + siglen - hlen - 1;
2604
2605 ret = mgf_mask(p, siglen - hlen - 1, hash_start, hlen, mgf1_hash_id);
2606 if (ret != 0) {
2607 return ret;
2608 }
2609
2610 buf[0] &= 0xFF >> (siglen * 8 - msb);
2611
2612 while (p < hash_start - 1 && *p == 0) {
2613 p++;
2614 }
2615
2616 if (*p++ != 0x01) {
2617 return MBEDTLS_ERR_RSA_INVALID_PADDING;
2618 }
2619
2620 observed_salt_len = (size_t) (hash_start - p);
2621
2622 if (expected_salt_len != MBEDTLS_RSA_SALT_LEN_ANY &&
2623 observed_salt_len != (size_t) expected_salt_len) {
2624 return MBEDTLS_ERR_RSA_INVALID_PADDING;
2625 }
2626
2627 /*
2628 * Generate H = Hash( M' )
2629 */
2630 ret = hash_mprime(hash, hashlen, p, observed_salt_len,
2631 result, mgf1_hash_id);
2632 if (ret != 0) {
2633 return ret;
2634 }
2635
2636 if (memcmp(hash_start, result, hlen) != 0) {
2637 return MBEDTLS_ERR_RSA_VERIFY_FAILED;
2638 }
2639
2640 return 0;
2641 }
2642
2643 /*
2644 * Simplified PKCS#1 v2.1 RSASSA-PSS-VERIFY function
2645 */
mbedtls_rsa_rsassa_pss_verify(mbedtls_rsa_context * ctx,mbedtls_md_type_t md_alg,unsigned int hashlen,const unsigned char * hash,const unsigned char * sig)2646 int mbedtls_rsa_rsassa_pss_verify(mbedtls_rsa_context *ctx,
2647 mbedtls_md_type_t md_alg,
2648 unsigned int hashlen,
2649 const unsigned char *hash,
2650 const unsigned char *sig)
2651 {
2652 mbedtls_md_type_t mgf1_hash_id;
2653 if ((md_alg != MBEDTLS_MD_NONE || hashlen != 0) && hash == NULL) {
2654 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2655 }
2656
2657 mgf1_hash_id = (ctx->hash_id != MBEDTLS_MD_NONE)
2658 ? (mbedtls_md_type_t) ctx->hash_id
2659 : md_alg;
2660
2661 return mbedtls_rsa_rsassa_pss_verify_ext(ctx,
2662 md_alg, hashlen, hash,
2663 mgf1_hash_id,
2664 MBEDTLS_RSA_SALT_LEN_ANY,
2665 sig);
2666
2667 }
2668 #endif /* MBEDTLS_PKCS1_V21 */
2669
2670 #if defined(MBEDTLS_PKCS1_V15)
2671 /*
2672 * Implementation of the PKCS#1 v2.1 RSASSA-PKCS1-v1_5-VERIFY function
2673 */
mbedtls_rsa_rsassa_pkcs1_v15_verify(mbedtls_rsa_context * ctx,mbedtls_md_type_t md_alg,unsigned int hashlen,const unsigned char * hash,const unsigned char * sig)2674 int mbedtls_rsa_rsassa_pkcs1_v15_verify(mbedtls_rsa_context *ctx,
2675 mbedtls_md_type_t md_alg,
2676 unsigned int hashlen,
2677 const unsigned char *hash,
2678 const unsigned char *sig)
2679 {
2680 int ret = 0;
2681 size_t sig_len;
2682 unsigned char *encoded = NULL, *encoded_expected = NULL;
2683
2684 if ((md_alg != MBEDTLS_MD_NONE || hashlen != 0) && hash == NULL) {
2685 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2686 }
2687
2688 sig_len = ctx->len;
2689
2690 /*
2691 * Prepare expected PKCS1 v1.5 encoding of hash.
2692 */
2693
2694 if ((encoded = mbedtls_calloc(1, sig_len)) == NULL ||
2695 (encoded_expected = mbedtls_calloc(1, sig_len)) == NULL) {
2696 ret = MBEDTLS_ERR_MPI_ALLOC_FAILED;
2697 goto cleanup;
2698 }
2699
2700 if ((ret = rsa_rsassa_pkcs1_v15_encode(md_alg, hashlen, hash, sig_len,
2701 encoded_expected)) != 0) {
2702 goto cleanup;
2703 }
2704
2705 /*
2706 * Apply RSA primitive to get what should be PKCS1 encoded hash.
2707 */
2708
2709 ret = mbedtls_rsa_public(ctx, sig, encoded);
2710 if (ret != 0) {
2711 goto cleanup;
2712 }
2713
2714 /*
2715 * Compare
2716 */
2717
2718 if ((ret = mbedtls_ct_memcmp(encoded, encoded_expected,
2719 sig_len)) != 0) {
2720 ret = MBEDTLS_ERR_RSA_VERIFY_FAILED;
2721 goto cleanup;
2722 }
2723
2724 cleanup:
2725
2726 if (encoded != NULL) {
2727 mbedtls_zeroize_and_free(encoded, sig_len);
2728 }
2729
2730 if (encoded_expected != NULL) {
2731 mbedtls_zeroize_and_free(encoded_expected, sig_len);
2732 }
2733
2734 return ret;
2735 }
2736 #endif /* MBEDTLS_PKCS1_V15 */
2737
2738 /*
2739 * Do an RSA operation and check the message digest
2740 */
mbedtls_rsa_pkcs1_verify(mbedtls_rsa_context * ctx,mbedtls_md_type_t md_alg,unsigned int hashlen,const unsigned char * hash,const unsigned char * sig)2741 int mbedtls_rsa_pkcs1_verify(mbedtls_rsa_context *ctx,
2742 mbedtls_md_type_t md_alg,
2743 unsigned int hashlen,
2744 const unsigned char *hash,
2745 const unsigned char *sig)
2746 {
2747 if ((md_alg != MBEDTLS_MD_NONE || hashlen != 0) && hash == NULL) {
2748 return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
2749 }
2750
2751 switch (ctx->padding) {
2752 #if defined(MBEDTLS_PKCS1_V15)
2753 case MBEDTLS_RSA_PKCS_V15:
2754 return mbedtls_rsa_rsassa_pkcs1_v15_verify(ctx, md_alg,
2755 hashlen, hash, sig);
2756 #endif
2757
2758 #if defined(MBEDTLS_PKCS1_V21)
2759 case MBEDTLS_RSA_PKCS_V21:
2760 return mbedtls_rsa_rsassa_pss_verify(ctx, md_alg,
2761 hashlen, hash, sig);
2762 #endif
2763
2764 default:
2765 return MBEDTLS_ERR_RSA_INVALID_PADDING;
2766 }
2767 }
2768
2769 /*
2770 * Copy the components of an RSA key
2771 */
mbedtls_rsa_copy(mbedtls_rsa_context * dst,const mbedtls_rsa_context * src)2772 int mbedtls_rsa_copy(mbedtls_rsa_context *dst, const mbedtls_rsa_context *src)
2773 {
2774 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
2775
2776 dst->len = src->len;
2777
2778 MBEDTLS_MPI_CHK(mbedtls_mpi_copy(&dst->N, &src->N));
2779 MBEDTLS_MPI_CHK(mbedtls_mpi_copy(&dst->E, &src->E));
2780
2781 MBEDTLS_MPI_CHK(mbedtls_mpi_copy(&dst->D, &src->D));
2782 MBEDTLS_MPI_CHK(mbedtls_mpi_copy(&dst->P, &src->P));
2783 MBEDTLS_MPI_CHK(mbedtls_mpi_copy(&dst->Q, &src->Q));
2784
2785 #if !defined(MBEDTLS_RSA_NO_CRT)
2786 MBEDTLS_MPI_CHK(mbedtls_mpi_copy(&dst->DP, &src->DP));
2787 MBEDTLS_MPI_CHK(mbedtls_mpi_copy(&dst->DQ, &src->DQ));
2788 MBEDTLS_MPI_CHK(mbedtls_mpi_copy(&dst->QP, &src->QP));
2789 MBEDTLS_MPI_CHK(mbedtls_mpi_copy(&dst->RP, &src->RP));
2790 MBEDTLS_MPI_CHK(mbedtls_mpi_copy(&dst->RQ, &src->RQ));
2791 #endif
2792
2793 MBEDTLS_MPI_CHK(mbedtls_mpi_copy(&dst->RN, &src->RN));
2794
2795 MBEDTLS_MPI_CHK(mbedtls_mpi_copy(&dst->Vi, &src->Vi));
2796 MBEDTLS_MPI_CHK(mbedtls_mpi_copy(&dst->Vf, &src->Vf));
2797
2798 dst->padding = src->padding;
2799 dst->hash_id = src->hash_id;
2800
2801 cleanup:
2802 if (ret != 0) {
2803 mbedtls_rsa_free(dst);
2804 }
2805
2806 return ret;
2807 }
2808
2809 /*
2810 * Free the components of an RSA key
2811 */
mbedtls_rsa_free(mbedtls_rsa_context * ctx)2812 void mbedtls_rsa_free(mbedtls_rsa_context *ctx)
2813 {
2814 if (ctx == NULL) {
2815 return;
2816 }
2817
2818 mbedtls_mpi_free(&ctx->Vi);
2819 mbedtls_mpi_free(&ctx->Vf);
2820 mbedtls_mpi_free(&ctx->RN);
2821 mbedtls_mpi_free(&ctx->D);
2822 mbedtls_mpi_free(&ctx->Q);
2823 mbedtls_mpi_free(&ctx->P);
2824 mbedtls_mpi_free(&ctx->E);
2825 mbedtls_mpi_free(&ctx->N);
2826
2827 #if !defined(MBEDTLS_RSA_NO_CRT)
2828 mbedtls_mpi_free(&ctx->RQ);
2829 mbedtls_mpi_free(&ctx->RP);
2830 mbedtls_mpi_free(&ctx->QP);
2831 mbedtls_mpi_free(&ctx->DQ);
2832 mbedtls_mpi_free(&ctx->DP);
2833 #endif /* MBEDTLS_RSA_NO_CRT */
2834
2835 #if defined(MBEDTLS_THREADING_C)
2836 /* Free the mutex, but only if it hasn't been freed already. */
2837 if (ctx->ver != 0) {
2838 mbedtls_mutex_free(&ctx->mutex);
2839 ctx->ver = 0;
2840 }
2841 #endif
2842 }
2843
2844 #endif /* !MBEDTLS_RSA_ALT */
2845
2846 #if defined(MBEDTLS_SELF_TEST)
2847
2848
2849 /*
2850 * Example RSA-1024 keypair, for test purposes
2851 */
2852 #define KEY_LEN 128
2853
2854 #define RSA_N "9292758453063D803DD603D5E777D788" \
2855 "8ED1D5BF35786190FA2F23EBC0848AEA" \
2856 "DDA92CA6C3D80B32C4D109BE0F36D6AE" \
2857 "7130B9CED7ACDF54CFC7555AC14EEBAB" \
2858 "93A89813FBF3C4F8066D2D800F7C38A8" \
2859 "1AE31942917403FF4946B0A83D3D3E05" \
2860 "EE57C6F5F5606FB5D4BC6CD34EE0801A" \
2861 "5E94BB77B07507233A0BC7BAC8F90F79"
2862
2863 #define RSA_E "10001"
2864
2865 #define RSA_D "24BF6185468786FDD303083D25E64EFC" \
2866 "66CA472BC44D253102F8B4A9D3BFA750" \
2867 "91386C0077937FE33FA3252D28855837" \
2868 "AE1B484A8A9A45F7EE8C0C634F99E8CD" \
2869 "DF79C5CE07EE72C7F123142198164234" \
2870 "CABB724CF78B8173B9F880FC86322407" \
2871 "AF1FEDFDDE2BEB674CA15F3E81A1521E" \
2872 "071513A1E85B5DFA031F21ECAE91A34D"
2873
2874 #define RSA_P "C36D0EB7FCD285223CFB5AABA5BDA3D8" \
2875 "2C01CAD19EA484A87EA4377637E75500" \
2876 "FCB2005C5C7DD6EC4AC023CDA285D796" \
2877 "C3D9E75E1EFC42488BB4F1D13AC30A57"
2878
2879 #define RSA_Q "C000DF51A7C77AE8D7C7370C1FF55B69" \
2880 "E211C2B9E5DB1ED0BF61D0D9899620F4" \
2881 "910E4168387E3C30AA1E00C339A79508" \
2882 "8452DD96A9A5EA5D9DCA68DA636032AF"
2883
2884 #define PT_LEN 24
2885 #define RSA_PT "\xAA\xBB\xCC\x03\x02\x01\x00\xFF\xFF\xFF\xFF\xFF" \
2886 "\x11\x22\x33\x0A\x0B\x0C\xCC\xDD\xDD\xDD\xDD\xDD"
2887
2888 #if defined(MBEDTLS_PKCS1_V15)
myrand(void * rng_state,unsigned char * output,size_t len)2889 static int myrand(void *rng_state, unsigned char *output, size_t len)
2890 {
2891 #if !defined(__OpenBSD__) && !defined(__NetBSD__)
2892 size_t i;
2893
2894 if (rng_state != NULL) {
2895 rng_state = NULL;
2896 }
2897
2898 for (i = 0; i < len; ++i) {
2899 output[i] = rand();
2900 }
2901 #else
2902 if (rng_state != NULL) {
2903 rng_state = NULL;
2904 }
2905
2906 arc4random_buf(output, len);
2907 #endif /* !OpenBSD && !NetBSD */
2908
2909 return 0;
2910 }
2911 #endif /* MBEDTLS_PKCS1_V15 */
2912
2913 /*
2914 * Checkup routine
2915 */
mbedtls_rsa_self_test(int verbose)2916 int mbedtls_rsa_self_test(int verbose)
2917 {
2918 int ret = 0;
2919 #if defined(MBEDTLS_PKCS1_V15)
2920 size_t len;
2921 mbedtls_rsa_context rsa;
2922 unsigned char rsa_plaintext[PT_LEN];
2923 unsigned char rsa_decrypted[PT_LEN];
2924 unsigned char rsa_ciphertext[KEY_LEN];
2925 #if defined(MBEDTLS_MD_CAN_SHA1)
2926 unsigned char sha1sum[20];
2927 #endif
2928
2929 mbedtls_mpi K;
2930
2931 mbedtls_mpi_init(&K);
2932 mbedtls_rsa_init(&rsa);
2933
2934 MBEDTLS_MPI_CHK(mbedtls_mpi_read_string(&K, 16, RSA_N));
2935 MBEDTLS_MPI_CHK(mbedtls_rsa_import(&rsa, &K, NULL, NULL, NULL, NULL));
2936 MBEDTLS_MPI_CHK(mbedtls_mpi_read_string(&K, 16, RSA_P));
2937 MBEDTLS_MPI_CHK(mbedtls_rsa_import(&rsa, NULL, &K, NULL, NULL, NULL));
2938 MBEDTLS_MPI_CHK(mbedtls_mpi_read_string(&K, 16, RSA_Q));
2939 MBEDTLS_MPI_CHK(mbedtls_rsa_import(&rsa, NULL, NULL, &K, NULL, NULL));
2940 MBEDTLS_MPI_CHK(mbedtls_mpi_read_string(&K, 16, RSA_D));
2941 MBEDTLS_MPI_CHK(mbedtls_rsa_import(&rsa, NULL, NULL, NULL, &K, NULL));
2942 MBEDTLS_MPI_CHK(mbedtls_mpi_read_string(&K, 16, RSA_E));
2943 MBEDTLS_MPI_CHK(mbedtls_rsa_import(&rsa, NULL, NULL, NULL, NULL, &K));
2944
2945 MBEDTLS_MPI_CHK(mbedtls_rsa_complete(&rsa));
2946
2947 if (verbose != 0) {
2948 mbedtls_printf(" RSA key validation: ");
2949 }
2950
2951 if (mbedtls_rsa_check_pubkey(&rsa) != 0 ||
2952 mbedtls_rsa_check_privkey(&rsa) != 0) {
2953 if (verbose != 0) {
2954 mbedtls_printf("failed\n");
2955 }
2956
2957 ret = 1;
2958 goto cleanup;
2959 }
2960
2961 if (verbose != 0) {
2962 mbedtls_printf("passed\n PKCS#1 encryption : ");
2963 }
2964
2965 memcpy(rsa_plaintext, RSA_PT, PT_LEN);
2966
2967 if (mbedtls_rsa_pkcs1_encrypt(&rsa, myrand, NULL,
2968 PT_LEN, rsa_plaintext,
2969 rsa_ciphertext) != 0) {
2970 if (verbose != 0) {
2971 mbedtls_printf("failed\n");
2972 }
2973
2974 ret = 1;
2975 goto cleanup;
2976 }
2977
2978 if (verbose != 0) {
2979 mbedtls_printf("passed\n PKCS#1 decryption : ");
2980 }
2981
2982 if (mbedtls_rsa_pkcs1_decrypt(&rsa, myrand, NULL,
2983 &len, rsa_ciphertext, rsa_decrypted,
2984 sizeof(rsa_decrypted)) != 0) {
2985 if (verbose != 0) {
2986 mbedtls_printf("failed\n");
2987 }
2988
2989 ret = 1;
2990 goto cleanup;
2991 }
2992
2993 if (memcmp(rsa_decrypted, rsa_plaintext, len) != 0) {
2994 if (verbose != 0) {
2995 mbedtls_printf("failed\n");
2996 }
2997
2998 ret = 1;
2999 goto cleanup;
3000 }
3001
3002 if (verbose != 0) {
3003 mbedtls_printf("passed\n");
3004 }
3005
3006 #if defined(MBEDTLS_MD_CAN_SHA1)
3007 if (verbose != 0) {
3008 mbedtls_printf(" PKCS#1 data sign : ");
3009 }
3010
3011 if (mbedtls_md(mbedtls_md_info_from_type(MBEDTLS_MD_SHA1),
3012 rsa_plaintext, PT_LEN, sha1sum) != 0) {
3013 if (verbose != 0) {
3014 mbedtls_printf("failed\n");
3015 }
3016
3017 return 1;
3018 }
3019
3020 if (mbedtls_rsa_pkcs1_sign(&rsa, myrand, NULL,
3021 MBEDTLS_MD_SHA1, 20,
3022 sha1sum, rsa_ciphertext) != 0) {
3023 if (verbose != 0) {
3024 mbedtls_printf("failed\n");
3025 }
3026
3027 ret = 1;
3028 goto cleanup;
3029 }
3030
3031 if (verbose != 0) {
3032 mbedtls_printf("passed\n PKCS#1 sig. verify: ");
3033 }
3034
3035 if (mbedtls_rsa_pkcs1_verify(&rsa, MBEDTLS_MD_SHA1, 20,
3036 sha1sum, rsa_ciphertext) != 0) {
3037 if (verbose != 0) {
3038 mbedtls_printf("failed\n");
3039 }
3040
3041 ret = 1;
3042 goto cleanup;
3043 }
3044
3045 if (verbose != 0) {
3046 mbedtls_printf("passed\n");
3047 }
3048 #endif /* MBEDTLS_MD_CAN_SHA1 */
3049
3050 if (verbose != 0) {
3051 mbedtls_printf("\n");
3052 }
3053
3054 cleanup:
3055 mbedtls_mpi_free(&K);
3056 mbedtls_rsa_free(&rsa);
3057 #else /* MBEDTLS_PKCS1_V15 */
3058 ((void) verbose);
3059 #endif /* MBEDTLS_PKCS1_V15 */
3060 return ret;
3061 }
3062
3063 #endif /* MBEDTLS_SELF_TEST */
3064
3065 #endif /* MBEDTLS_RSA_C */
3066
