1 /*
2 * The LMS stateful-hash public-key signature scheme
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 LMS algorithm:
11 *
12 * [1] IETF RFC8554
13 * D. McGrew, M. Curcio, S.Fluhrer
14 * https://datatracker.ietf.org/doc/html/rfc8554
15 *
16 * [2] NIST Special Publication 800-208
17 * David A. Cooper et. al.
18 * https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-208.pdf
19 */
20
21 #include "common.h"
22
23 #if defined(MBEDTLS_LMS_C)
24
25 #include <string.h>
26
27 #include "lmots.h"
28
29 #include "psa/crypto.h"
30 #include "psa_util_internal.h"
31 #include "mbedtls/lms.h"
32 #include "mbedtls/error.h"
33 #include "mbedtls/platform_util.h"
34
35 #include "mbedtls/platform.h"
36
37 /* Define a local translating function to save code size by not using too many
38 * arguments in each translating place. */
local_err_translation(psa_status_t status)39 static int local_err_translation(psa_status_t status)
40 {
41 return psa_status_to_mbedtls(status, psa_to_lms_errors,
42 ARRAY_LENGTH(psa_to_lms_errors),
43 psa_generic_status_to_mbedtls);
44 }
45 #define PSA_TO_MBEDTLS_ERR(status) local_err_translation(status)
46
47 #define SIG_Q_LEAF_ID_OFFSET (0)
48 #define SIG_OTS_SIG_OFFSET (SIG_Q_LEAF_ID_OFFSET + \
49 MBEDTLS_LMOTS_Q_LEAF_ID_LEN)
50 #define SIG_TYPE_OFFSET(otstype) (SIG_OTS_SIG_OFFSET + \
51 MBEDTLS_LMOTS_SIG_LEN(otstype))
52 #define SIG_PATH_OFFSET(otstype) (SIG_TYPE_OFFSET(otstype) + \
53 MBEDTLS_LMS_TYPE_LEN)
54
55 #define PUBLIC_KEY_TYPE_OFFSET (0)
56 #define PUBLIC_KEY_OTSTYPE_OFFSET (PUBLIC_KEY_TYPE_OFFSET + \
57 MBEDTLS_LMS_TYPE_LEN)
58 #define PUBLIC_KEY_I_KEY_ID_OFFSET (PUBLIC_KEY_OTSTYPE_OFFSET + \
59 MBEDTLS_LMOTS_TYPE_LEN)
60 #define PUBLIC_KEY_ROOT_NODE_OFFSET (PUBLIC_KEY_I_KEY_ID_OFFSET + \
61 MBEDTLS_LMOTS_I_KEY_ID_LEN)
62
63
64 /* Currently only support H=10 */
65 #define H_TREE_HEIGHT_MAX 10
66 #define MERKLE_TREE_NODE_AM(type) ((size_t) 1 << (MBEDTLS_LMS_H_TREE_HEIGHT(type) + 1u))
67 #define MERKLE_TREE_LEAF_NODE_AM(type) ((size_t) 1 << MBEDTLS_LMS_H_TREE_HEIGHT(type))
68 #define MERKLE_TREE_INTERNAL_NODE_AM(type) ((unsigned int) \
69 (1u << MBEDTLS_LMS_H_TREE_HEIGHT(type)))
70
71 #define D_CONST_LEN (2)
72 static const unsigned char D_LEAF_CONSTANT_BYTES[D_CONST_LEN] = { 0x82, 0x82 };
73 static const unsigned char D_INTR_CONSTANT_BYTES[D_CONST_LEN] = { 0x83, 0x83 };
74
75
76 /* Calculate the value of a leaf node of the Merkle tree (which is a hash of a
77 * public key and some other parameters like the leaf index). This function
78 * implements RFC8554 section 5.3, in the case where r >= 2^h.
79 *
80 * params The LMS parameter set, the underlying LMOTS
81 * parameter set, and I value which describe the key
82 * being used.
83 *
84 * pub_key The public key of the private whose index
85 * corresponds to the index of this leaf node. This
86 * is a hash output.
87 *
88 * r_node_idx The index of this node in the Merkle tree. Note
89 * that the root node of the Merkle tree is
90 * 1-indexed.
91 *
92 * out The output node value, which is a hash output.
93 */
create_merkle_leaf_value(const mbedtls_lms_parameters_t * params,unsigned char * pub_key,unsigned int r_node_idx,unsigned char * out)94 static int create_merkle_leaf_value(const mbedtls_lms_parameters_t *params,
95 unsigned char *pub_key,
96 unsigned int r_node_idx,
97 unsigned char *out)
98 {
99 psa_hash_operation_t op;
100 psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
101 size_t output_hash_len;
102 unsigned char r_node_idx_bytes[4];
103
104 /* Always zeroize the output buffer because it may contain data from the previous invocation */
105 memset(out, 0, MBEDTLS_LMS_M_NODE_BYTES(params->type));
106
107 op = psa_hash_operation_init();
108 status = psa_hash_setup(&op, PSA_ALG_SHA_256);
109 if (status != PSA_SUCCESS) {
110 goto exit;
111 }
112
113 status = psa_hash_update(&op, params->I_key_identifier,
114 MBEDTLS_LMOTS_I_KEY_ID_LEN);
115 if (status != PSA_SUCCESS) {
116 goto exit;
117 }
118
119 MBEDTLS_PUT_UINT32_BE(r_node_idx, r_node_idx_bytes, 0);
120 status = psa_hash_update(&op, r_node_idx_bytes, 4);
121 if (status != PSA_SUCCESS) {
122 goto exit;
123 }
124
125 status = psa_hash_update(&op, D_LEAF_CONSTANT_BYTES, D_CONST_LEN);
126 if (status != PSA_SUCCESS) {
127 goto exit;
128 }
129
130 status = psa_hash_update(&op, pub_key,
131 MBEDTLS_LMOTS_N_HASH_LEN(params->otstype));
132 if (status != PSA_SUCCESS) {
133 goto exit;
134 }
135
136 status = psa_hash_finish(&op, out, MBEDTLS_LMS_M_NODE_BYTES(params->type),
137 &output_hash_len);
138 if (status != PSA_SUCCESS) {
139 goto exit;
140 }
141
142 exit:
143 psa_hash_abort(&op);
144
145 return PSA_TO_MBEDTLS_ERR(status);
146 }
147
148 /* Calculate the value of an internal node of the Merkle tree (which is a hash
149 * of a public key and some other parameters like the node index). This function
150 * implements RFC8554 section 5.3, in the case where r < 2^h.
151 *
152 * params The LMS parameter set, the underlying LMOTS
153 * parameter set, and I value which describe the key
154 * being used.
155 *
156 * left_node The value of the child of this node which is on
157 * the left-hand side. As with all nodes on the
158 * Merkle tree, this is a hash output.
159 *
160 * right_node The value of the child of this node which is on
161 * the right-hand side. As with all nodes on the
162 * Merkle tree, this is a hash output.
163 *
164 * r_node_idx The index of this node in the Merkle tree. Note
165 * that the root node of the Merkle tree is
166 * 1-indexed.
167 *
168 * out The output node value, which is a hash output.
169 */
create_merkle_internal_value(const mbedtls_lms_parameters_t * params,const unsigned char * left_node,const unsigned char * right_node,unsigned int r_node_idx,unsigned char * out)170 static int create_merkle_internal_value(const mbedtls_lms_parameters_t *params,
171 const unsigned char *left_node,
172 const unsigned char *right_node,
173 unsigned int r_node_idx,
174 unsigned char *out)
175 {
176 psa_hash_operation_t op;
177 psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
178 size_t output_hash_len;
179 unsigned char r_node_idx_bytes[4];
180
181 op = psa_hash_operation_init();
182 status = psa_hash_setup(&op, PSA_ALG_SHA_256);
183 if (status != PSA_SUCCESS) {
184 goto exit;
185 }
186
187 status = psa_hash_update(&op, params->I_key_identifier,
188 MBEDTLS_LMOTS_I_KEY_ID_LEN);
189 if (status != PSA_SUCCESS) {
190 goto exit;
191 }
192
193 MBEDTLS_PUT_UINT32_BE(r_node_idx, r_node_idx_bytes, 0);
194 status = psa_hash_update(&op, r_node_idx_bytes, 4);
195 if (status != PSA_SUCCESS) {
196 goto exit;
197 }
198
199 status = psa_hash_update(&op, D_INTR_CONSTANT_BYTES, D_CONST_LEN);
200 if (status != PSA_SUCCESS) {
201 goto exit;
202 }
203
204 status = psa_hash_update(&op, left_node,
205 MBEDTLS_LMS_M_NODE_BYTES(params->type));
206 if (status != PSA_SUCCESS) {
207 goto exit;
208 }
209
210 status = psa_hash_update(&op, right_node,
211 MBEDTLS_LMS_M_NODE_BYTES(params->type));
212 if (status != PSA_SUCCESS) {
213 goto exit;
214 }
215
216 status = psa_hash_finish(&op, out, MBEDTLS_LMS_M_NODE_BYTES(params->type),
217 &output_hash_len);
218 if (status != PSA_SUCCESS) {
219 goto exit;
220 }
221
222 exit:
223 psa_hash_abort(&op);
224
225 return PSA_TO_MBEDTLS_ERR(status);
226 }
227
mbedtls_lms_public_init(mbedtls_lms_public_t * ctx)228 void mbedtls_lms_public_init(mbedtls_lms_public_t *ctx)
229 {
230 memset(ctx, 0, sizeof(*ctx));
231 }
232
mbedtls_lms_public_free(mbedtls_lms_public_t * ctx)233 void mbedtls_lms_public_free(mbedtls_lms_public_t *ctx)
234 {
235 mbedtls_platform_zeroize(ctx, sizeof(*ctx));
236 }
237
mbedtls_lms_import_public_key(mbedtls_lms_public_t * ctx,const unsigned char * key,size_t key_size)238 int mbedtls_lms_import_public_key(mbedtls_lms_public_t *ctx,
239 const unsigned char *key, size_t key_size)
240 {
241 if (key_size < 4) {
242 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
243 }
244
245 uint32_t type = MBEDTLS_GET_UINT32_BE(key, PUBLIC_KEY_TYPE_OFFSET);
246 if (type != (uint32_t) MBEDTLS_LMS_SHA256_M32_H10) {
247 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
248 }
249 ctx->params.type = (mbedtls_lms_algorithm_type_t) type;
250
251 if (key_size != MBEDTLS_LMS_PUBLIC_KEY_LEN(ctx->params.type)) {
252 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
253 }
254
255 uint32_t otstype = MBEDTLS_GET_UINT32_BE(key, PUBLIC_KEY_OTSTYPE_OFFSET);
256 if (otstype != (uint32_t) MBEDTLS_LMOTS_SHA256_N32_W8) {
257 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
258 }
259 ctx->params.otstype = (mbedtls_lmots_algorithm_type_t) otstype;
260
261 memcpy(ctx->params.I_key_identifier,
262 key + PUBLIC_KEY_I_KEY_ID_OFFSET,
263 MBEDTLS_LMOTS_I_KEY_ID_LEN);
264 memcpy(ctx->T_1_pub_key, key + PUBLIC_KEY_ROOT_NODE_OFFSET,
265 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type));
266
267 ctx->have_public_key = 1;
268
269 return 0;
270 }
271
mbedtls_lms_export_public_key(const mbedtls_lms_public_t * ctx,unsigned char * key,size_t key_size,size_t * key_len)272 int mbedtls_lms_export_public_key(const mbedtls_lms_public_t *ctx,
273 unsigned char *key,
274 size_t key_size, size_t *key_len)
275 {
276 if (key_size < MBEDTLS_LMS_PUBLIC_KEY_LEN(ctx->params.type)) {
277 return MBEDTLS_ERR_LMS_BUFFER_TOO_SMALL;
278 }
279
280 if (!ctx->have_public_key) {
281 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
282 }
283
284 MBEDTLS_PUT_UINT32_BE(ctx->params.type, key, PUBLIC_KEY_TYPE_OFFSET);
285 MBEDTLS_PUT_UINT32_BE(ctx->params.otstype, key, PUBLIC_KEY_OTSTYPE_OFFSET);
286 memcpy(key + PUBLIC_KEY_I_KEY_ID_OFFSET,
287 ctx->params.I_key_identifier,
288 MBEDTLS_LMOTS_I_KEY_ID_LEN);
289 memcpy(key +PUBLIC_KEY_ROOT_NODE_OFFSET,
290 ctx->T_1_pub_key,
291 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type));
292
293 if (key_len != NULL) {
294 *key_len = MBEDTLS_LMS_PUBLIC_KEY_LEN(ctx->params.type);
295 }
296
297 return 0;
298 }
299
mbedtls_lms_verify(const mbedtls_lms_public_t * ctx,const unsigned char * msg,size_t msg_size,const unsigned char * sig,size_t sig_size)300 int mbedtls_lms_verify(const mbedtls_lms_public_t *ctx,
301 const unsigned char *msg, size_t msg_size,
302 const unsigned char *sig, size_t sig_size)
303 {
304 unsigned int q_leaf_identifier;
305 unsigned char Kc_candidate_ots_pub_key[MBEDTLS_LMOTS_N_HASH_LEN_MAX];
306 unsigned char Tc_candidate_root_node[MBEDTLS_LMS_M_NODE_BYTES_MAX];
307 unsigned int height;
308 unsigned int curr_node_id;
309 unsigned int parent_node_id;
310 const unsigned char *left_node;
311 const unsigned char *right_node;
312 mbedtls_lmots_parameters_t ots_params;
313 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
314
315 if (!ctx->have_public_key) {
316 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
317 }
318
319 if (ctx->params.type
320 != MBEDTLS_LMS_SHA256_M32_H10) {
321 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
322 }
323
324 if (ctx->params.otstype
325 != MBEDTLS_LMOTS_SHA256_N32_W8) {
326 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
327 }
328
329 if (sig_size != MBEDTLS_LMS_SIG_LEN(ctx->params.type, ctx->params.otstype)) {
330 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
331 }
332
333 if (sig_size < SIG_OTS_SIG_OFFSET + MBEDTLS_LMOTS_TYPE_LEN) {
334 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
335 }
336
337 if (MBEDTLS_GET_UINT32_BE(sig, SIG_OTS_SIG_OFFSET + MBEDTLS_LMOTS_SIG_TYPE_OFFSET)
338 != MBEDTLS_LMOTS_SHA256_N32_W8) {
339 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
340 }
341
342 if (sig_size < SIG_TYPE_OFFSET(ctx->params.otstype) + MBEDTLS_LMS_TYPE_LEN) {
343 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
344 }
345
346 if (MBEDTLS_GET_UINT32_BE(sig, SIG_TYPE_OFFSET(ctx->params.otstype))
347 != MBEDTLS_LMS_SHA256_M32_H10) {
348 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
349 }
350
351
352 q_leaf_identifier = MBEDTLS_GET_UINT32_BE(sig, SIG_Q_LEAF_ID_OFFSET);
353
354 if (q_leaf_identifier >= MERKLE_TREE_LEAF_NODE_AM(ctx->params.type)) {
355 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
356 }
357
358 memcpy(ots_params.I_key_identifier,
359 ctx->params.I_key_identifier,
360 MBEDTLS_LMOTS_I_KEY_ID_LEN);
361 MBEDTLS_PUT_UINT32_BE(q_leaf_identifier, ots_params.q_leaf_identifier, 0);
362 ots_params.type = ctx->params.otstype;
363
364 ret = mbedtls_lmots_calculate_public_key_candidate(&ots_params,
365 msg,
366 msg_size,
367 sig + SIG_OTS_SIG_OFFSET,
368 MBEDTLS_LMOTS_SIG_LEN(ctx->params.otstype),
369 Kc_candidate_ots_pub_key,
370 sizeof(Kc_candidate_ots_pub_key),
371 NULL);
372 if (ret != 0) {
373 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
374 }
375
376 ret = create_merkle_leaf_value(
377 &ctx->params,
378 Kc_candidate_ots_pub_key,
379 MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type) + q_leaf_identifier,
380 Tc_candidate_root_node);
381
382 if (ret != 0) {
383 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
384 }
385
386 curr_node_id = MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type) +
387 q_leaf_identifier;
388
389 for (height = 0; height < MBEDTLS_LMS_H_TREE_HEIGHT(ctx->params.type);
390 height++) {
391 parent_node_id = curr_node_id / 2;
392
393 /* Left/right node ordering matters for the hash */
394 if (curr_node_id & 1) {
395 left_node = sig + SIG_PATH_OFFSET(ctx->params.otstype) +
396 height * MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type);
397 right_node = Tc_candidate_root_node;
398 } else {
399 left_node = Tc_candidate_root_node;
400 right_node = sig + SIG_PATH_OFFSET(ctx->params.otstype) +
401 height * MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type);
402 }
403
404 ret = create_merkle_internal_value(&ctx->params, left_node, right_node,
405 parent_node_id, Tc_candidate_root_node);
406 if (ret != 0) {
407 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
408 }
409 curr_node_id /= 2;
410 }
411
412 if (memcmp(Tc_candidate_root_node, ctx->T_1_pub_key,
413 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type))) {
414 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
415 }
416
417 return 0;
418 }
419
420 #if defined(MBEDTLS_LMS_PRIVATE)
421
422 /* Calculate a full Merkle tree based on a private key. This function
423 * implements RFC8554 section 5.3, and is used to generate a public key (as the
424 * public key is the root node of the Merkle tree).
425 *
426 * ctx The LMS private context, containing a parameter
427 * set and private key material consisting of both
428 * public and private OTS.
429 *
430 * tree The output tree, which is 2^(H + 1) hash outputs.
431 * In the case of H=10 we have 2048 tree nodes (of
432 * which 1024 of them are leaf nodes). Note that
433 * because the Merkle tree root is 1-indexed, the 0
434 * index tree node is never used.
435 */
calculate_merkle_tree(const mbedtls_lms_private_t * ctx,unsigned char * tree)436 static int calculate_merkle_tree(const mbedtls_lms_private_t *ctx,
437 unsigned char *tree)
438 {
439 unsigned int priv_key_idx;
440 unsigned int r_node_idx;
441 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
442
443 /* First create the leaf nodes, in ascending order */
444 for (priv_key_idx = 0;
445 priv_key_idx < MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type);
446 priv_key_idx++) {
447 r_node_idx = MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type) + priv_key_idx;
448
449 ret = create_merkle_leaf_value(&ctx->params,
450 ctx->ots_public_keys[priv_key_idx].public_key,
451 r_node_idx,
452 &tree[r_node_idx * MBEDTLS_LMS_M_NODE_BYTES(
453 ctx->params.type)]);
454 if (ret != 0) {
455 return ret;
456 }
457 }
458
459 /* Then the internal nodes, in reverse order so that we can guarantee the
460 * parent has been created */
461 for (r_node_idx = MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type) - 1;
462 r_node_idx > 0;
463 r_node_idx--) {
464 ret = create_merkle_internal_value(&ctx->params,
465 &tree[(r_node_idx * 2) *
466 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type)],
467 &tree[(r_node_idx * 2 + 1) *
468 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type)],
469 r_node_idx,
470 &tree[r_node_idx *
471 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type)]);
472 if (ret != 0) {
473 return ret;
474 }
475 }
476
477 return 0;
478 }
479
480 /* Calculate a path from a leaf node of the Merkle tree to the root of the tree,
481 * and return the full path. This function implements RFC8554 section 5.4.1, as
482 * the Merkle path is the main component of an LMS signature.
483 *
484 * ctx The LMS private context, containing a parameter
485 * set and private key material consisting of both
486 * public and private OTS.
487 *
488 * leaf_node_id Which leaf node to calculate the path from.
489 *
490 * path The output path, which is H hash outputs.
491 */
get_merkle_path(mbedtls_lms_private_t * ctx,unsigned int leaf_node_id,unsigned char * path)492 static int get_merkle_path(mbedtls_lms_private_t *ctx,
493 unsigned int leaf_node_id,
494 unsigned char *path)
495 {
496 const size_t node_bytes = MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type);
497 unsigned int curr_node_id = leaf_node_id;
498 unsigned int adjacent_node_id;
499 unsigned char *tree = NULL;
500 unsigned int height;
501 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
502
503 tree = mbedtls_calloc((size_t) MERKLE_TREE_NODE_AM(ctx->params.type),
504 node_bytes);
505 if (tree == NULL) {
506 return MBEDTLS_ERR_LMS_ALLOC_FAILED;
507 }
508
509 ret = calculate_merkle_tree(ctx, tree);
510 if (ret != 0) {
511 goto exit;
512 }
513
514 for (height = 0; height < MBEDTLS_LMS_H_TREE_HEIGHT(ctx->params.type);
515 height++) {
516 adjacent_node_id = curr_node_id ^ 1;
517
518 memcpy(&path[height * node_bytes],
519 &tree[adjacent_node_id * node_bytes], node_bytes);
520
521 curr_node_id >>= 1;
522 }
523
524 ret = 0;
525
526 exit:
527 mbedtls_zeroize_and_free(tree, node_bytes *
528 (size_t) MERKLE_TREE_NODE_AM(ctx->params.type));
529
530 return ret;
531 }
532
mbedtls_lms_private_init(mbedtls_lms_private_t * ctx)533 void mbedtls_lms_private_init(mbedtls_lms_private_t *ctx)
534 {
535 memset(ctx, 0, sizeof(*ctx));
536 }
537
mbedtls_lms_private_free(mbedtls_lms_private_t * ctx)538 void mbedtls_lms_private_free(mbedtls_lms_private_t *ctx)
539 {
540 unsigned int idx;
541
542 if (ctx->have_private_key) {
543 if (ctx->ots_private_keys != NULL) {
544 for (idx = 0; idx < MERKLE_TREE_LEAF_NODE_AM(ctx->params.type); idx++) {
545 mbedtls_lmots_private_free(&ctx->ots_private_keys[idx]);
546 }
547 }
548
549 if (ctx->ots_public_keys != NULL) {
550 for (idx = 0; idx < MERKLE_TREE_LEAF_NODE_AM(ctx->params.type); idx++) {
551 mbedtls_lmots_public_free(&ctx->ots_public_keys[idx]);
552 }
553 }
554
555 mbedtls_free(ctx->ots_private_keys);
556 mbedtls_free(ctx->ots_public_keys);
557 }
558
559 mbedtls_platform_zeroize(ctx, sizeof(*ctx));
560 }
561
562
mbedtls_lms_generate_private_key(mbedtls_lms_private_t * ctx,mbedtls_lms_algorithm_type_t type,mbedtls_lmots_algorithm_type_t otstype,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng,const unsigned char * seed,size_t seed_size)563 int mbedtls_lms_generate_private_key(mbedtls_lms_private_t *ctx,
564 mbedtls_lms_algorithm_type_t type,
565 mbedtls_lmots_algorithm_type_t otstype,
566 int (*f_rng)(void *, unsigned char *, size_t),
567 void *p_rng, const unsigned char *seed,
568 size_t seed_size)
569 {
570 unsigned int idx = 0;
571 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
572
573 if (type != MBEDTLS_LMS_SHA256_M32_H10) {
574 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
575 }
576
577 if (otstype != MBEDTLS_LMOTS_SHA256_N32_W8) {
578 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
579 }
580
581 if (ctx->have_private_key) {
582 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
583 }
584
585 ctx->params.type = type;
586 ctx->params.otstype = otstype;
587 ctx->have_private_key = 1;
588
589 ret = f_rng(p_rng,
590 ctx->params.I_key_identifier,
591 MBEDTLS_LMOTS_I_KEY_ID_LEN);
592 if (ret != 0) {
593 goto exit;
594 }
595
596 /* Requires a cast to size_t to avoid an implicit cast warning on certain
597 * platforms (particularly Windows) */
598 ctx->ots_private_keys = mbedtls_calloc((size_t) MERKLE_TREE_LEAF_NODE_AM(ctx->params.type),
599 sizeof(*ctx->ots_private_keys));
600 if (ctx->ots_private_keys == NULL) {
601 ret = MBEDTLS_ERR_LMS_ALLOC_FAILED;
602 goto exit;
603 }
604
605 /* Requires a cast to size_t to avoid an implicit cast warning on certain
606 * platforms (particularly Windows) */
607 ctx->ots_public_keys = mbedtls_calloc((size_t) MERKLE_TREE_LEAF_NODE_AM(ctx->params.type),
608 sizeof(*ctx->ots_public_keys));
609 if (ctx->ots_public_keys == NULL) {
610 ret = MBEDTLS_ERR_LMS_ALLOC_FAILED;
611 goto exit;
612 }
613
614 for (idx = 0; idx < MERKLE_TREE_LEAF_NODE_AM(ctx->params.type); idx++) {
615 mbedtls_lmots_private_init(&ctx->ots_private_keys[idx]);
616 mbedtls_lmots_public_init(&ctx->ots_public_keys[idx]);
617 }
618
619
620 for (idx = 0; idx < MERKLE_TREE_LEAF_NODE_AM(ctx->params.type); idx++) {
621 ret = mbedtls_lmots_generate_private_key(&ctx->ots_private_keys[idx],
622 otstype,
623 ctx->params.I_key_identifier,
624 idx, seed, seed_size);
625 if (ret != 0) {
626 goto exit;
627 }
628
629 ret = mbedtls_lmots_calculate_public_key(&ctx->ots_public_keys[idx],
630 &ctx->ots_private_keys[idx]);
631 if (ret != 0) {
632 goto exit;
633 }
634 }
635
636 ctx->q_next_usable_key = 0;
637
638 exit:
639 if (ret != 0) {
640 mbedtls_lms_private_free(ctx);
641 }
642
643 return ret;
644 }
645
mbedtls_lms_calculate_public_key(mbedtls_lms_public_t * ctx,const mbedtls_lms_private_t * priv_ctx)646 int mbedtls_lms_calculate_public_key(mbedtls_lms_public_t *ctx,
647 const mbedtls_lms_private_t *priv_ctx)
648 {
649 const size_t node_bytes = MBEDTLS_LMS_M_NODE_BYTES(priv_ctx->params.type);
650 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
651 unsigned char *tree = NULL;
652
653 if (!priv_ctx->have_private_key) {
654 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
655 }
656
657 if (priv_ctx->params.type
658 != MBEDTLS_LMS_SHA256_M32_H10) {
659 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
660 }
661
662 if (priv_ctx->params.otstype
663 != MBEDTLS_LMOTS_SHA256_N32_W8) {
664 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
665 }
666
667 tree = mbedtls_calloc((size_t) MERKLE_TREE_NODE_AM(priv_ctx->params.type),
668 node_bytes);
669 if (tree == NULL) {
670 return MBEDTLS_ERR_LMS_ALLOC_FAILED;
671 }
672
673 memcpy(&ctx->params, &priv_ctx->params,
674 sizeof(mbedtls_lmots_parameters_t));
675
676 ret = calculate_merkle_tree(priv_ctx, tree);
677 if (ret != 0) {
678 goto exit;
679 }
680
681 /* Root node is always at position 1, due to 1-based indexing */
682 memcpy(ctx->T_1_pub_key, &tree[node_bytes], node_bytes);
683
684 ctx->have_public_key = 1;
685
686 ret = 0;
687
688 exit:
689 mbedtls_zeroize_and_free(tree, node_bytes *
690 (size_t) MERKLE_TREE_NODE_AM(priv_ctx->params.type));
691
692 return ret;
693 }
694
695
mbedtls_lms_sign(mbedtls_lms_private_t * ctx,int (* f_rng)(void *,unsigned char *,size_t),void * p_rng,const unsigned char * msg,unsigned int msg_size,unsigned char * sig,size_t sig_size,size_t * sig_len)696 int mbedtls_lms_sign(mbedtls_lms_private_t *ctx,
697 int (*f_rng)(void *, unsigned char *, size_t),
698 void *p_rng, const unsigned char *msg,
699 unsigned int msg_size, unsigned char *sig, size_t sig_size,
700 size_t *sig_len)
701 {
702 uint32_t q_leaf_identifier;
703 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
704
705 if (!ctx->have_private_key) {
706 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
707 }
708
709 if (sig_size < MBEDTLS_LMS_SIG_LEN(ctx->params.type, ctx->params.otstype)) {
710 return MBEDTLS_ERR_LMS_BUFFER_TOO_SMALL;
711 }
712
713 if (ctx->params.type != MBEDTLS_LMS_SHA256_M32_H10) {
714 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
715 }
716
717 if (ctx->params.otstype
718 != MBEDTLS_LMOTS_SHA256_N32_W8) {
719 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
720 }
721
722 if (ctx->q_next_usable_key >= MERKLE_TREE_LEAF_NODE_AM(ctx->params.type)) {
723 return MBEDTLS_ERR_LMS_OUT_OF_PRIVATE_KEYS;
724 }
725
726
727 q_leaf_identifier = ctx->q_next_usable_key;
728 /* This new value must _always_ be written back to the disk before the
729 * signature is returned.
730 */
731 ctx->q_next_usable_key += 1;
732
733 if (MBEDTLS_LMS_SIG_LEN(ctx->params.type, ctx->params.otstype)
734 < SIG_OTS_SIG_OFFSET) {
735 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
736 }
737
738 ret = mbedtls_lmots_sign(&ctx->ots_private_keys[q_leaf_identifier],
739 f_rng,
740 p_rng,
741 msg,
742 msg_size,
743 sig + SIG_OTS_SIG_OFFSET,
744 MBEDTLS_LMS_SIG_LEN(ctx->params.type,
745 ctx->params.otstype) - SIG_OTS_SIG_OFFSET,
746 NULL);
747 if (ret != 0) {
748 return ret;
749 }
750
751 MBEDTLS_PUT_UINT32_BE(ctx->params.type, sig, SIG_TYPE_OFFSET(ctx->params.otstype));
752 MBEDTLS_PUT_UINT32_BE(q_leaf_identifier, sig, SIG_Q_LEAF_ID_OFFSET);
753
754 ret = get_merkle_path(ctx,
755 MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type) + q_leaf_identifier,
756 sig + SIG_PATH_OFFSET(ctx->params.otstype));
757 if (ret != 0) {
758 return ret;
759 }
760
761 if (sig_len != NULL) {
762 *sig_len = MBEDTLS_LMS_SIG_LEN(ctx->params.type, ctx->params.otstype);
763 }
764
765
766 return 0;
767 }
768
769 #endif /* defined(MBEDTLS_LMS_PRIVATE) */
770 #endif /* defined(MBEDTLS_LMS_C) */
771