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