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 if (ctx == NULL) {
236 return;
237 }
238
239 mbedtls_platform_zeroize(ctx, sizeof(*ctx));
240 }
241
mbedtls_lms_import_public_key(mbedtls_lms_public_t * ctx,const unsigned char * key,size_t key_size)242 int mbedtls_lms_import_public_key(mbedtls_lms_public_t *ctx,
243 const unsigned char *key, size_t key_size)
244 {
245 if (key_size < 4) {
246 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
247 }
248
249 uint32_t type = MBEDTLS_GET_UINT32_BE(key, PUBLIC_KEY_TYPE_OFFSET);
250 if (type != (uint32_t) MBEDTLS_LMS_SHA256_M32_H10) {
251 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
252 }
253 ctx->params.type = (mbedtls_lms_algorithm_type_t) type;
254
255 if (key_size != MBEDTLS_LMS_PUBLIC_KEY_LEN(ctx->params.type)) {
256 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
257 }
258
259 uint32_t otstype = MBEDTLS_GET_UINT32_BE(key, PUBLIC_KEY_OTSTYPE_OFFSET);
260 if (otstype != (uint32_t) MBEDTLS_LMOTS_SHA256_N32_W8) {
261 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
262 }
263 ctx->params.otstype = (mbedtls_lmots_algorithm_type_t) otstype;
264
265 memcpy(ctx->params.I_key_identifier,
266 key + PUBLIC_KEY_I_KEY_ID_OFFSET,
267 MBEDTLS_LMOTS_I_KEY_ID_LEN);
268 memcpy(ctx->T_1_pub_key, key + PUBLIC_KEY_ROOT_NODE_OFFSET,
269 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type));
270
271 ctx->have_public_key = 1;
272
273 return 0;
274 }
275
mbedtls_lms_export_public_key(const mbedtls_lms_public_t * ctx,unsigned char * key,size_t key_size,size_t * key_len)276 int mbedtls_lms_export_public_key(const mbedtls_lms_public_t *ctx,
277 unsigned char *key,
278 size_t key_size, size_t *key_len)
279 {
280 if (key_size < MBEDTLS_LMS_PUBLIC_KEY_LEN(ctx->params.type)) {
281 return MBEDTLS_ERR_LMS_BUFFER_TOO_SMALL;
282 }
283
284 if (!ctx->have_public_key) {
285 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
286 }
287
288 MBEDTLS_PUT_UINT32_BE(ctx->params.type, key, PUBLIC_KEY_TYPE_OFFSET);
289 MBEDTLS_PUT_UINT32_BE(ctx->params.otstype, key, PUBLIC_KEY_OTSTYPE_OFFSET);
290 memcpy(key + PUBLIC_KEY_I_KEY_ID_OFFSET,
291 ctx->params.I_key_identifier,
292 MBEDTLS_LMOTS_I_KEY_ID_LEN);
293 memcpy(key +PUBLIC_KEY_ROOT_NODE_OFFSET,
294 ctx->T_1_pub_key,
295 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type));
296
297 if (key_len != NULL) {
298 *key_len = MBEDTLS_LMS_PUBLIC_KEY_LEN(ctx->params.type);
299 }
300
301 return 0;
302 }
303
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)304 int mbedtls_lms_verify(const mbedtls_lms_public_t *ctx,
305 const unsigned char *msg, size_t msg_size,
306 const unsigned char *sig, size_t sig_size)
307 {
308 unsigned int q_leaf_identifier;
309 unsigned char Kc_candidate_ots_pub_key[MBEDTLS_LMOTS_N_HASH_LEN_MAX];
310 unsigned char Tc_candidate_root_node[MBEDTLS_LMS_M_NODE_BYTES_MAX];
311 unsigned int height;
312 unsigned int curr_node_id;
313 unsigned int parent_node_id;
314 const unsigned char *left_node;
315 const unsigned char *right_node;
316 mbedtls_lmots_parameters_t ots_params;
317 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
318
319 if (!ctx->have_public_key) {
320 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
321 }
322
323 if (ctx->params.type
324 != MBEDTLS_LMS_SHA256_M32_H10) {
325 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
326 }
327
328 if (ctx->params.otstype
329 != MBEDTLS_LMOTS_SHA256_N32_W8) {
330 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
331 }
332
333 if (sig_size != MBEDTLS_LMS_SIG_LEN(ctx->params.type, ctx->params.otstype)) {
334 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
335 }
336
337 if (sig_size < SIG_OTS_SIG_OFFSET + MBEDTLS_LMOTS_TYPE_LEN) {
338 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
339 }
340
341 if (MBEDTLS_GET_UINT32_BE(sig, SIG_OTS_SIG_OFFSET + MBEDTLS_LMOTS_SIG_TYPE_OFFSET)
342 != MBEDTLS_LMOTS_SHA256_N32_W8) {
343 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
344 }
345
346 if (sig_size < SIG_TYPE_OFFSET(ctx->params.otstype) + MBEDTLS_LMS_TYPE_LEN) {
347 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
348 }
349
350 if (MBEDTLS_GET_UINT32_BE(sig, SIG_TYPE_OFFSET(ctx->params.otstype))
351 != MBEDTLS_LMS_SHA256_M32_H10) {
352 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
353 }
354
355
356 q_leaf_identifier = MBEDTLS_GET_UINT32_BE(sig, SIG_Q_LEAF_ID_OFFSET);
357
358 if (q_leaf_identifier >= MERKLE_TREE_LEAF_NODE_AM(ctx->params.type)) {
359 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
360 }
361
362 memcpy(ots_params.I_key_identifier,
363 ctx->params.I_key_identifier,
364 MBEDTLS_LMOTS_I_KEY_ID_LEN);
365 MBEDTLS_PUT_UINT32_BE(q_leaf_identifier, ots_params.q_leaf_identifier, 0);
366 ots_params.type = ctx->params.otstype;
367
368 ret = mbedtls_lmots_calculate_public_key_candidate(&ots_params,
369 msg,
370 msg_size,
371 sig + SIG_OTS_SIG_OFFSET,
372 MBEDTLS_LMOTS_SIG_LEN(ctx->params.otstype),
373 Kc_candidate_ots_pub_key,
374 sizeof(Kc_candidate_ots_pub_key),
375 NULL);
376 if (ret != 0) {
377 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
378 }
379
380 ret = create_merkle_leaf_value(
381 &ctx->params,
382 Kc_candidate_ots_pub_key,
383 MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type) + q_leaf_identifier,
384 Tc_candidate_root_node);
385
386 if (ret != 0) {
387 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
388 }
389
390 curr_node_id = MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type) +
391 q_leaf_identifier;
392
393 for (height = 0; height < MBEDTLS_LMS_H_TREE_HEIGHT(ctx->params.type);
394 height++) {
395 parent_node_id = curr_node_id / 2;
396
397 /* Left/right node ordering matters for the hash */
398 if (curr_node_id & 1) {
399 left_node = sig + SIG_PATH_OFFSET(ctx->params.otstype) +
400 height * MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type);
401 right_node = Tc_candidate_root_node;
402 } else {
403 left_node = Tc_candidate_root_node;
404 right_node = sig + SIG_PATH_OFFSET(ctx->params.otstype) +
405 height * MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type);
406 }
407
408 ret = create_merkle_internal_value(&ctx->params, left_node, right_node,
409 parent_node_id, Tc_candidate_root_node);
410 if (ret != 0) {
411 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
412 }
413 curr_node_id /= 2;
414 }
415
416 if (memcmp(Tc_candidate_root_node, ctx->T_1_pub_key,
417 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type))) {
418 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
419 }
420
421 return 0;
422 }
423
424 #if defined(MBEDTLS_LMS_PRIVATE)
425
426 /* Calculate a full Merkle tree based on a private key. This function
427 * implements RFC8554 section 5.3, and is used to generate a public key (as the
428 * public key is the root node of the Merkle tree).
429 *
430 * ctx The LMS private context, containing a parameter
431 * set and private key material consisting of both
432 * public and private OTS.
433 *
434 * tree The output tree, which is 2^(H + 1) hash outputs.
435 * In the case of H=10 we have 2048 tree nodes (of
436 * which 1024 of them are leaf nodes). Note that
437 * because the Merkle tree root is 1-indexed, the 0
438 * index tree node is never used.
439 */
calculate_merkle_tree(const mbedtls_lms_private_t * ctx,unsigned char * tree)440 static int calculate_merkle_tree(const mbedtls_lms_private_t *ctx,
441 unsigned char *tree)
442 {
443 unsigned int priv_key_idx;
444 unsigned int r_node_idx;
445 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
446
447 /* First create the leaf nodes, in ascending order */
448 for (priv_key_idx = 0;
449 priv_key_idx < MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type);
450 priv_key_idx++) {
451 r_node_idx = MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type) + priv_key_idx;
452
453 ret = create_merkle_leaf_value(&ctx->params,
454 ctx->ots_public_keys[priv_key_idx].public_key,
455 r_node_idx,
456 &tree[r_node_idx * MBEDTLS_LMS_M_NODE_BYTES(
457 ctx->params.type)]);
458 if (ret != 0) {
459 return ret;
460 }
461 }
462
463 /* Then the internal nodes, in reverse order so that we can guarantee the
464 * parent has been created */
465 for (r_node_idx = MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type) - 1;
466 r_node_idx > 0;
467 r_node_idx--) {
468 ret = create_merkle_internal_value(&ctx->params,
469 &tree[(r_node_idx * 2) *
470 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type)],
471 &tree[(r_node_idx * 2 + 1) *
472 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type)],
473 r_node_idx,
474 &tree[r_node_idx *
475 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type)]);
476 if (ret != 0) {
477 return ret;
478 }
479 }
480
481 return 0;
482 }
483
484 /* Calculate a path from a leaf node of the Merkle tree to the root of the tree,
485 * and return the full path. This function implements RFC8554 section 5.4.1, as
486 * the Merkle path is the main component of an LMS signature.
487 *
488 * ctx The LMS private context, containing a parameter
489 * set and private key material consisting of both
490 * public and private OTS.
491 *
492 * leaf_node_id Which leaf node to calculate the path from.
493 *
494 * path The output path, which is H hash outputs.
495 */
get_merkle_path(mbedtls_lms_private_t * ctx,unsigned int leaf_node_id,unsigned char * path)496 static int get_merkle_path(mbedtls_lms_private_t *ctx,
497 unsigned int leaf_node_id,
498 unsigned char *path)
499 {
500 const size_t node_bytes = MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type);
501 unsigned int curr_node_id = leaf_node_id;
502 unsigned int adjacent_node_id;
503 unsigned char *tree = NULL;
504 unsigned int height;
505 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
506
507 tree = mbedtls_calloc((size_t) MERKLE_TREE_NODE_AM(ctx->params.type),
508 node_bytes);
509 if (tree == NULL) {
510 return MBEDTLS_ERR_LMS_ALLOC_FAILED;
511 }
512
513 ret = calculate_merkle_tree(ctx, tree);
514 if (ret != 0) {
515 goto exit;
516 }
517
518 for (height = 0; height < MBEDTLS_LMS_H_TREE_HEIGHT(ctx->params.type);
519 height++) {
520 adjacent_node_id = curr_node_id ^ 1;
521
522 memcpy(&path[height * node_bytes],
523 &tree[adjacent_node_id * node_bytes], node_bytes);
524
525 curr_node_id >>= 1;
526 }
527
528 ret = 0;
529
530 exit:
531 mbedtls_zeroize_and_free(tree, node_bytes *
532 (size_t) MERKLE_TREE_NODE_AM(ctx->params.type));
533
534 return ret;
535 }
536
mbedtls_lms_private_init(mbedtls_lms_private_t * ctx)537 void mbedtls_lms_private_init(mbedtls_lms_private_t *ctx)
538 {
539 memset(ctx, 0, sizeof(*ctx));
540 }
541
mbedtls_lms_private_free(mbedtls_lms_private_t * ctx)542 void mbedtls_lms_private_free(mbedtls_lms_private_t *ctx)
543 {
544 if (ctx == NULL) {
545 return;
546 }
547
548 unsigned int idx;
549
550 if (ctx->have_private_key) {
551 if (ctx->ots_private_keys != NULL) {
552 for (idx = 0; idx < MERKLE_TREE_LEAF_NODE_AM(ctx->params.type); idx++) {
553 mbedtls_lmots_private_free(&ctx->ots_private_keys[idx]);
554 }
555 }
556
557 if (ctx->ots_public_keys != NULL) {
558 for (idx = 0; idx < MERKLE_TREE_LEAF_NODE_AM(ctx->params.type); idx++) {
559 mbedtls_lmots_public_free(&ctx->ots_public_keys[idx]);
560 }
561 }
562
563 mbedtls_free(ctx->ots_private_keys);
564 mbedtls_free(ctx->ots_public_keys);
565 }
566
567 mbedtls_platform_zeroize(ctx, sizeof(*ctx));
568 }
569
570
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)571 int mbedtls_lms_generate_private_key(mbedtls_lms_private_t *ctx,
572 mbedtls_lms_algorithm_type_t type,
573 mbedtls_lmots_algorithm_type_t otstype,
574 int (*f_rng)(void *, unsigned char *, size_t),
575 void *p_rng, const unsigned char *seed,
576 size_t seed_size)
577 {
578 unsigned int idx = 0;
579 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
580
581 if (type != MBEDTLS_LMS_SHA256_M32_H10) {
582 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
583 }
584
585 if (otstype != MBEDTLS_LMOTS_SHA256_N32_W8) {
586 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
587 }
588
589 if (ctx->have_private_key) {
590 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
591 }
592
593 ctx->params.type = type;
594 ctx->params.otstype = otstype;
595 ctx->have_private_key = 1;
596
597 ret = f_rng(p_rng,
598 ctx->params.I_key_identifier,
599 MBEDTLS_LMOTS_I_KEY_ID_LEN);
600 if (ret != 0) {
601 goto exit;
602 }
603
604 /* Requires a cast to size_t to avoid an implicit cast warning on certain
605 * platforms (particularly Windows) */
606 ctx->ots_private_keys = mbedtls_calloc((size_t) MERKLE_TREE_LEAF_NODE_AM(ctx->params.type),
607 sizeof(*ctx->ots_private_keys));
608 if (ctx->ots_private_keys == NULL) {
609 ret = MBEDTLS_ERR_LMS_ALLOC_FAILED;
610 goto exit;
611 }
612
613 /* Requires a cast to size_t to avoid an implicit cast warning on certain
614 * platforms (particularly Windows) */
615 ctx->ots_public_keys = mbedtls_calloc((size_t) MERKLE_TREE_LEAF_NODE_AM(ctx->params.type),
616 sizeof(*ctx->ots_public_keys));
617 if (ctx->ots_public_keys == NULL) {
618 ret = MBEDTLS_ERR_LMS_ALLOC_FAILED;
619 goto exit;
620 }
621
622 for (idx = 0; idx < MERKLE_TREE_LEAF_NODE_AM(ctx->params.type); idx++) {
623 mbedtls_lmots_private_init(&ctx->ots_private_keys[idx]);
624 mbedtls_lmots_public_init(&ctx->ots_public_keys[idx]);
625 }
626
627
628 for (idx = 0; idx < MERKLE_TREE_LEAF_NODE_AM(ctx->params.type); idx++) {
629 ret = mbedtls_lmots_generate_private_key(&ctx->ots_private_keys[idx],
630 otstype,
631 ctx->params.I_key_identifier,
632 idx, seed, seed_size);
633 if (ret != 0) {
634 goto exit;
635 }
636
637 ret = mbedtls_lmots_calculate_public_key(&ctx->ots_public_keys[idx],
638 &ctx->ots_private_keys[idx]);
639 if (ret != 0) {
640 goto exit;
641 }
642 }
643
644 ctx->q_next_usable_key = 0;
645
646 exit:
647 if (ret != 0) {
648 mbedtls_lms_private_free(ctx);
649 }
650
651 return ret;
652 }
653
mbedtls_lms_calculate_public_key(mbedtls_lms_public_t * ctx,const mbedtls_lms_private_t * priv_ctx)654 int mbedtls_lms_calculate_public_key(mbedtls_lms_public_t *ctx,
655 const mbedtls_lms_private_t *priv_ctx)
656 {
657 const size_t node_bytes = MBEDTLS_LMS_M_NODE_BYTES(priv_ctx->params.type);
658 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
659 unsigned char *tree = NULL;
660
661 if (!priv_ctx->have_private_key) {
662 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
663 }
664
665 if (priv_ctx->params.type
666 != MBEDTLS_LMS_SHA256_M32_H10) {
667 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
668 }
669
670 if (priv_ctx->params.otstype
671 != MBEDTLS_LMOTS_SHA256_N32_W8) {
672 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
673 }
674
675 tree = mbedtls_calloc((size_t) MERKLE_TREE_NODE_AM(priv_ctx->params.type),
676 node_bytes);
677 if (tree == NULL) {
678 return MBEDTLS_ERR_LMS_ALLOC_FAILED;
679 }
680
681 memcpy(&ctx->params, &priv_ctx->params,
682 sizeof(mbedtls_lmots_parameters_t));
683
684 ret = calculate_merkle_tree(priv_ctx, tree);
685 if (ret != 0) {
686 goto exit;
687 }
688
689 /* Root node is always at position 1, due to 1-based indexing */
690 memcpy(ctx->T_1_pub_key, &tree[node_bytes], node_bytes);
691
692 ctx->have_public_key = 1;
693
694 ret = 0;
695
696 exit:
697 mbedtls_zeroize_and_free(tree, node_bytes *
698 (size_t) MERKLE_TREE_NODE_AM(priv_ctx->params.type));
699
700 return ret;
701 }
702
703
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)704 int mbedtls_lms_sign(mbedtls_lms_private_t *ctx,
705 int (*f_rng)(void *, unsigned char *, size_t),
706 void *p_rng, const unsigned char *msg,
707 unsigned int msg_size, unsigned char *sig, size_t sig_size,
708 size_t *sig_len)
709 {
710 uint32_t q_leaf_identifier;
711 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
712
713 if (!ctx->have_private_key) {
714 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
715 }
716
717 if (sig_size < MBEDTLS_LMS_SIG_LEN(ctx->params.type, ctx->params.otstype)) {
718 return MBEDTLS_ERR_LMS_BUFFER_TOO_SMALL;
719 }
720
721 if (ctx->params.type != MBEDTLS_LMS_SHA256_M32_H10) {
722 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
723 }
724
725 if (ctx->params.otstype
726 != MBEDTLS_LMOTS_SHA256_N32_W8) {
727 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
728 }
729
730 if (ctx->q_next_usable_key >= MERKLE_TREE_LEAF_NODE_AM(ctx->params.type)) {
731 return MBEDTLS_ERR_LMS_OUT_OF_PRIVATE_KEYS;
732 }
733
734
735 q_leaf_identifier = ctx->q_next_usable_key;
736 /* This new value must _always_ be written back to the disk before the
737 * signature is returned.
738 */
739 ctx->q_next_usable_key += 1;
740
741 if (MBEDTLS_LMS_SIG_LEN(ctx->params.type, ctx->params.otstype)
742 < SIG_OTS_SIG_OFFSET) {
743 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
744 }
745
746 ret = mbedtls_lmots_sign(&ctx->ots_private_keys[q_leaf_identifier],
747 f_rng,
748 p_rng,
749 msg,
750 msg_size,
751 sig + SIG_OTS_SIG_OFFSET,
752 MBEDTLS_LMS_SIG_LEN(ctx->params.type,
753 ctx->params.otstype) - SIG_OTS_SIG_OFFSET,
754 NULL);
755 if (ret != 0) {
756 return ret;
757 }
758
759 MBEDTLS_PUT_UINT32_BE(ctx->params.type, sig, SIG_TYPE_OFFSET(ctx->params.otstype));
760 MBEDTLS_PUT_UINT32_BE(q_leaf_identifier, sig, SIG_Q_LEAF_ID_OFFSET);
761
762 ret = get_merkle_path(ctx,
763 MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type) + q_leaf_identifier,
764 sig + SIG_PATH_OFFSET(ctx->params.otstype));
765 if (ret != 0) {
766 return ret;
767 }
768
769 if (sig_len != NULL) {
770 *sig_len = MBEDTLS_LMS_SIG_LEN(ctx->params.type, ctx->params.otstype);
771 }
772
773
774 return 0;
775 }
776
777 #endif /* defined(MBEDTLS_LMS_PRIVATE) */
778 #endif /* defined(MBEDTLS_LMS_C) */
779