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 mbedtls_platform_zeroize(ctx, sizeof(*ctx));
233 }
234
mbedtls_lms_import_public_key(mbedtls_lms_public_t * ctx,const unsigned char * key,size_t key_size)235 int mbedtls_lms_import_public_key(mbedtls_lms_public_t *ctx,
236 const unsigned char *key, size_t key_size)
237 {
238 mbedtls_lms_algorithm_type_t type;
239 mbedtls_lmots_algorithm_type_t otstype;
240
241 type = (mbedtls_lms_algorithm_type_t) MBEDTLS_GET_UINT32_BE(key, PUBLIC_KEY_TYPE_OFFSET);
242 if (type != MBEDTLS_LMS_SHA256_M32_H10) {
243 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
244 }
245 ctx->params.type = type;
246
247 if (key_size != MBEDTLS_LMS_PUBLIC_KEY_LEN(ctx->params.type)) {
248 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
249 }
250
251 otstype = (mbedtls_lmots_algorithm_type_t)
252 MBEDTLS_GET_UINT32_BE(key, PUBLIC_KEY_OTSTYPE_OFFSET);
253 if (otstype != MBEDTLS_LMOTS_SHA256_N32_W8) {
254 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
255 }
256 ctx->params.otstype = otstype;
257
258 memcpy(ctx->params.I_key_identifier,
259 key + PUBLIC_KEY_I_KEY_ID_OFFSET,
260 MBEDTLS_LMOTS_I_KEY_ID_LEN);
261 memcpy(ctx->T_1_pub_key, key + PUBLIC_KEY_ROOT_NODE_OFFSET,
262 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type));
263
264 ctx->have_public_key = 1;
265
266 return 0;
267 }
268
mbedtls_lms_export_public_key(const mbedtls_lms_public_t * ctx,unsigned char * key,size_t key_size,size_t * key_len)269 int mbedtls_lms_export_public_key(const mbedtls_lms_public_t *ctx,
270 unsigned char *key,
271 size_t key_size, size_t *key_len)
272 {
273 if (key_size < MBEDTLS_LMS_PUBLIC_KEY_LEN(ctx->params.type)) {
274 return MBEDTLS_ERR_LMS_BUFFER_TOO_SMALL;
275 }
276
277 if (!ctx->have_public_key) {
278 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
279 }
280
281 MBEDTLS_PUT_UINT32_BE(ctx->params.type, key, PUBLIC_KEY_TYPE_OFFSET);
282 MBEDTLS_PUT_UINT32_BE(ctx->params.otstype, key, PUBLIC_KEY_OTSTYPE_OFFSET);
283 memcpy(key + PUBLIC_KEY_I_KEY_ID_OFFSET,
284 ctx->params.I_key_identifier,
285 MBEDTLS_LMOTS_I_KEY_ID_LEN);
286 memcpy(key +PUBLIC_KEY_ROOT_NODE_OFFSET,
287 ctx->T_1_pub_key,
288 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type));
289
290 if (key_len != NULL) {
291 *key_len = MBEDTLS_LMS_PUBLIC_KEY_LEN(ctx->params.type);
292 }
293
294 return 0;
295 }
296
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)297 int mbedtls_lms_verify(const mbedtls_lms_public_t *ctx,
298 const unsigned char *msg, size_t msg_size,
299 const unsigned char *sig, size_t sig_size)
300 {
301 unsigned int q_leaf_identifier;
302 unsigned char Kc_candidate_ots_pub_key[MBEDTLS_LMOTS_N_HASH_LEN_MAX];
303 unsigned char Tc_candidate_root_node[MBEDTLS_LMS_M_NODE_BYTES_MAX];
304 unsigned int height;
305 unsigned int curr_node_id;
306 unsigned int parent_node_id;
307 const unsigned char *left_node;
308 const unsigned char *right_node;
309 mbedtls_lmots_parameters_t ots_params;
310 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
311
312 if (!ctx->have_public_key) {
313 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
314 }
315
316 if (ctx->params.type
317 != MBEDTLS_LMS_SHA256_M32_H10) {
318 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
319 }
320
321 if (ctx->params.otstype
322 != MBEDTLS_LMOTS_SHA256_N32_W8) {
323 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
324 }
325
326 if (sig_size != MBEDTLS_LMS_SIG_LEN(ctx->params.type, ctx->params.otstype)) {
327 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
328 }
329
330 if (sig_size < SIG_OTS_SIG_OFFSET + MBEDTLS_LMOTS_TYPE_LEN) {
331 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
332 }
333
334 if (MBEDTLS_GET_UINT32_BE(sig, SIG_OTS_SIG_OFFSET + MBEDTLS_LMOTS_SIG_TYPE_OFFSET)
335 != MBEDTLS_LMOTS_SHA256_N32_W8) {
336 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
337 }
338
339 if (sig_size < SIG_TYPE_OFFSET(ctx->params.otstype) + MBEDTLS_LMS_TYPE_LEN) {
340 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
341 }
342
343 if (MBEDTLS_GET_UINT32_BE(sig, SIG_TYPE_OFFSET(ctx->params.otstype))
344 != MBEDTLS_LMS_SHA256_M32_H10) {
345 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
346 }
347
348
349 q_leaf_identifier = MBEDTLS_GET_UINT32_BE(sig, SIG_Q_LEAF_ID_OFFSET);
350
351 if (q_leaf_identifier >= MERKLE_TREE_LEAF_NODE_AM(ctx->params.type)) {
352 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
353 }
354
355 memcpy(ots_params.I_key_identifier,
356 ctx->params.I_key_identifier,
357 MBEDTLS_LMOTS_I_KEY_ID_LEN);
358 MBEDTLS_PUT_UINT32_BE(q_leaf_identifier, ots_params.q_leaf_identifier, 0);
359 ots_params.type = ctx->params.otstype;
360
361 ret = mbedtls_lmots_calculate_public_key_candidate(&ots_params,
362 msg,
363 msg_size,
364 sig + SIG_OTS_SIG_OFFSET,
365 MBEDTLS_LMOTS_SIG_LEN(ctx->params.otstype),
366 Kc_candidate_ots_pub_key,
367 sizeof(Kc_candidate_ots_pub_key),
368 NULL);
369 if (ret != 0) {
370 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
371 }
372
373 create_merkle_leaf_value(
374 &ctx->params,
375 Kc_candidate_ots_pub_key,
376 MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type) + q_leaf_identifier,
377 Tc_candidate_root_node);
378
379 curr_node_id = MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type) +
380 q_leaf_identifier;
381
382 for (height = 0; height < MBEDTLS_LMS_H_TREE_HEIGHT(ctx->params.type);
383 height++) {
384 parent_node_id = curr_node_id / 2;
385
386 /* Left/right node ordering matters for the hash */
387 if (curr_node_id & 1) {
388 left_node = sig + SIG_PATH_OFFSET(ctx->params.otstype) +
389 height * MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type);
390 right_node = Tc_candidate_root_node;
391 } else {
392 left_node = Tc_candidate_root_node;
393 right_node = sig + SIG_PATH_OFFSET(ctx->params.otstype) +
394 height * MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type);
395 }
396
397 create_merkle_internal_value(&ctx->params, left_node, right_node,
398 parent_node_id, Tc_candidate_root_node);
399
400 curr_node_id /= 2;
401 }
402
403 if (memcmp(Tc_candidate_root_node, ctx->T_1_pub_key,
404 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type))) {
405 return MBEDTLS_ERR_LMS_VERIFY_FAILED;
406 }
407
408 return 0;
409 }
410
411 #if defined(MBEDTLS_LMS_PRIVATE)
412
413 /* Calculate a full Merkle tree based on a private key. This function
414 * implements RFC8554 section 5.3, and is used to generate a public key (as the
415 * public key is the root node of the Merkle tree).
416 *
417 * ctx The LMS private context, containing a parameter
418 * set and private key material consisting of both
419 * public and private OTS.
420 *
421 * tree The output tree, which is 2^(H + 1) hash outputs.
422 * In the case of H=10 we have 2048 tree nodes (of
423 * which 1024 of them are leaf nodes). Note that
424 * because the Merkle tree root is 1-indexed, the 0
425 * index tree node is never used.
426 */
calculate_merkle_tree(const mbedtls_lms_private_t * ctx,unsigned char * tree)427 static int calculate_merkle_tree(const mbedtls_lms_private_t *ctx,
428 unsigned char *tree)
429 {
430 unsigned int priv_key_idx;
431 unsigned int r_node_idx;
432 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
433
434 /* First create the leaf nodes, in ascending order */
435 for (priv_key_idx = 0;
436 priv_key_idx < MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type);
437 priv_key_idx++) {
438 r_node_idx = MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type) + priv_key_idx;
439
440 ret = create_merkle_leaf_value(&ctx->params,
441 ctx->ots_public_keys[priv_key_idx].public_key,
442 r_node_idx,
443 &tree[r_node_idx * MBEDTLS_LMS_M_NODE_BYTES(
444 ctx->params.type)]);
445 if (ret != 0) {
446 return ret;
447 }
448 }
449
450 /* Then the internal nodes, in reverse order so that we can guarantee the
451 * parent has been created */
452 for (r_node_idx = MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type) - 1;
453 r_node_idx > 0;
454 r_node_idx--) {
455 ret = create_merkle_internal_value(&ctx->params,
456 &tree[(r_node_idx * 2) *
457 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type)],
458 &tree[(r_node_idx * 2 + 1) *
459 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type)],
460 r_node_idx,
461 &tree[r_node_idx *
462 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type)]);
463 if (ret != 0) {
464 return ret;
465 }
466 }
467
468 return 0;
469 }
470
471 /* Calculate a path from a leaf node of the Merkle tree to the root of the tree,
472 * and return the full path. This function implements RFC8554 section 5.4.1, as
473 * the Merkle path is the main component of an LMS signature.
474 *
475 * ctx The LMS private context, containing a parameter
476 * set and private key material consisting of both
477 * public and private OTS.
478 *
479 * leaf_node_id Which leaf node to calculate the path from.
480 *
481 * path The output path, which is H hash outputs.
482 */
get_merkle_path(mbedtls_lms_private_t * ctx,unsigned int leaf_node_id,unsigned char * path)483 static int get_merkle_path(mbedtls_lms_private_t *ctx,
484 unsigned int leaf_node_id,
485 unsigned char *path)
486 {
487 const size_t node_bytes = MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type);
488 unsigned int curr_node_id = leaf_node_id;
489 unsigned int adjacent_node_id;
490 unsigned char *tree = NULL;
491 unsigned int height;
492 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
493
494 tree = mbedtls_calloc((size_t) MERKLE_TREE_NODE_AM(ctx->params.type),
495 node_bytes);
496 if (tree == NULL) {
497 return MBEDTLS_ERR_LMS_ALLOC_FAILED;
498 }
499
500 ret = calculate_merkle_tree(ctx, tree);
501 if (ret != 0) {
502 goto exit;
503 }
504
505 for (height = 0; height < MBEDTLS_LMS_H_TREE_HEIGHT(ctx->params.type);
506 height++) {
507 adjacent_node_id = curr_node_id ^ 1;
508
509 memcpy(&path[height * node_bytes],
510 &tree[adjacent_node_id * node_bytes], node_bytes);
511
512 curr_node_id >>= 1;
513 }
514
515 ret = 0;
516
517 exit:
518 mbedtls_zeroize_and_free(tree, node_bytes *
519 (size_t) MERKLE_TREE_NODE_AM(ctx->params.type));
520
521 return ret;
522 }
523
mbedtls_lms_private_init(mbedtls_lms_private_t * ctx)524 void mbedtls_lms_private_init(mbedtls_lms_private_t *ctx)
525 {
526 memset(ctx, 0, sizeof(*ctx));
527 }
528
mbedtls_lms_private_free(mbedtls_lms_private_t * ctx)529 void mbedtls_lms_private_free(mbedtls_lms_private_t *ctx)
530 {
531 unsigned int idx;
532
533 if (ctx->have_private_key) {
534 if (ctx->ots_private_keys != NULL) {
535 for (idx = 0; idx < MERKLE_TREE_LEAF_NODE_AM(ctx->params.type); idx++) {
536 mbedtls_lmots_private_free(&ctx->ots_private_keys[idx]);
537 }
538 }
539
540 if (ctx->ots_public_keys != NULL) {
541 for (idx = 0; idx < MERKLE_TREE_LEAF_NODE_AM(ctx->params.type); idx++) {
542 mbedtls_lmots_public_free(&ctx->ots_public_keys[idx]);
543 }
544 }
545
546 mbedtls_free(ctx->ots_private_keys);
547 mbedtls_free(ctx->ots_public_keys);
548 }
549
550 mbedtls_platform_zeroize(ctx, sizeof(*ctx));
551 }
552
553
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)554 int mbedtls_lms_generate_private_key(mbedtls_lms_private_t *ctx,
555 mbedtls_lms_algorithm_type_t type,
556 mbedtls_lmots_algorithm_type_t otstype,
557 int (*f_rng)(void *, unsigned char *, size_t),
558 void *p_rng, const unsigned char *seed,
559 size_t seed_size)
560 {
561 unsigned int idx = 0;
562 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
563
564 if (type != MBEDTLS_LMS_SHA256_M32_H10) {
565 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
566 }
567
568 if (otstype != MBEDTLS_LMOTS_SHA256_N32_W8) {
569 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
570 }
571
572 if (ctx->have_private_key) {
573 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
574 }
575
576 ctx->params.type = type;
577 ctx->params.otstype = otstype;
578 ctx->have_private_key = 1;
579
580 ret = f_rng(p_rng,
581 ctx->params.I_key_identifier,
582 MBEDTLS_LMOTS_I_KEY_ID_LEN);
583 if (ret != 0) {
584 goto exit;
585 }
586
587 /* Requires a cast to size_t to avoid an implicit cast warning on certain
588 * platforms (particularly Windows) */
589 ctx->ots_private_keys = mbedtls_calloc((size_t) MERKLE_TREE_LEAF_NODE_AM(ctx->params.type),
590 sizeof(*ctx->ots_private_keys));
591 if (ctx->ots_private_keys == NULL) {
592 ret = MBEDTLS_ERR_LMS_ALLOC_FAILED;
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_public_keys = mbedtls_calloc((size_t) MERKLE_TREE_LEAF_NODE_AM(ctx->params.type),
599 sizeof(*ctx->ots_public_keys));
600 if (ctx->ots_public_keys == NULL) {
601 ret = MBEDTLS_ERR_LMS_ALLOC_FAILED;
602 goto exit;
603 }
604
605 for (idx = 0; idx < MERKLE_TREE_LEAF_NODE_AM(ctx->params.type); idx++) {
606 mbedtls_lmots_private_init(&ctx->ots_private_keys[idx]);
607 mbedtls_lmots_public_init(&ctx->ots_public_keys[idx]);
608 }
609
610
611 for (idx = 0; idx < MERKLE_TREE_LEAF_NODE_AM(ctx->params.type); idx++) {
612 ret = mbedtls_lmots_generate_private_key(&ctx->ots_private_keys[idx],
613 otstype,
614 ctx->params.I_key_identifier,
615 idx, seed, seed_size);
616 if (ret != 0) {
617 goto exit;
618 }
619
620 ret = mbedtls_lmots_calculate_public_key(&ctx->ots_public_keys[idx],
621 &ctx->ots_private_keys[idx]);
622 if (ret != 0) {
623 goto exit;
624 }
625 }
626
627 ctx->q_next_usable_key = 0;
628
629 exit:
630 if (ret != 0) {
631 mbedtls_lms_private_free(ctx);
632 }
633
634 return ret;
635 }
636
mbedtls_lms_calculate_public_key(mbedtls_lms_public_t * ctx,const mbedtls_lms_private_t * priv_ctx)637 int mbedtls_lms_calculate_public_key(mbedtls_lms_public_t *ctx,
638 const mbedtls_lms_private_t *priv_ctx)
639 {
640 const size_t node_bytes = MBEDTLS_LMS_M_NODE_BYTES(priv_ctx->params.type);
641 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
642 unsigned char *tree = NULL;
643
644 if (!priv_ctx->have_private_key) {
645 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
646 }
647
648 if (priv_ctx->params.type
649 != MBEDTLS_LMS_SHA256_M32_H10) {
650 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
651 }
652
653 if (priv_ctx->params.otstype
654 != MBEDTLS_LMOTS_SHA256_N32_W8) {
655 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
656 }
657
658 tree = mbedtls_calloc((size_t) MERKLE_TREE_NODE_AM(priv_ctx->params.type),
659 node_bytes);
660 if (tree == NULL) {
661 return MBEDTLS_ERR_LMS_ALLOC_FAILED;
662 }
663
664 memcpy(&ctx->params, &priv_ctx->params,
665 sizeof(mbedtls_lmots_parameters_t));
666
667 ret = calculate_merkle_tree(priv_ctx, tree);
668 if (ret != 0) {
669 goto exit;
670 }
671
672 /* Root node is always at position 1, due to 1-based indexing */
673 memcpy(ctx->T_1_pub_key, &tree[node_bytes], node_bytes);
674
675 ctx->have_public_key = 1;
676
677 ret = 0;
678
679 exit:
680 mbedtls_zeroize_and_free(tree, node_bytes *
681 (size_t) MERKLE_TREE_NODE_AM(priv_ctx->params.type));
682
683 return ret;
684 }
685
686
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)687 int mbedtls_lms_sign(mbedtls_lms_private_t *ctx,
688 int (*f_rng)(void *, unsigned char *, size_t),
689 void *p_rng, const unsigned char *msg,
690 unsigned int msg_size, unsigned char *sig, size_t sig_size,
691 size_t *sig_len)
692 {
693 uint32_t q_leaf_identifier;
694 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
695
696 if (!ctx->have_private_key) {
697 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
698 }
699
700 if (sig_size < MBEDTLS_LMS_SIG_LEN(ctx->params.type, ctx->params.otstype)) {
701 return MBEDTLS_ERR_LMS_BUFFER_TOO_SMALL;
702 }
703
704 if (ctx->params.type != MBEDTLS_LMS_SHA256_M32_H10) {
705 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
706 }
707
708 if (ctx->params.otstype
709 != MBEDTLS_LMOTS_SHA256_N32_W8) {
710 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
711 }
712
713 if (ctx->q_next_usable_key >= MERKLE_TREE_LEAF_NODE_AM(ctx->params.type)) {
714 return MBEDTLS_ERR_LMS_OUT_OF_PRIVATE_KEYS;
715 }
716
717
718 q_leaf_identifier = ctx->q_next_usable_key;
719 /* This new value must _always_ be written back to the disk before the
720 * signature is returned.
721 */
722 ctx->q_next_usable_key += 1;
723
724 if (MBEDTLS_LMS_SIG_LEN(ctx->params.type, ctx->params.otstype)
725 < SIG_OTS_SIG_OFFSET) {
726 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA;
727 }
728
729 ret = mbedtls_lmots_sign(&ctx->ots_private_keys[q_leaf_identifier],
730 f_rng,
731 p_rng,
732 msg,
733 msg_size,
734 sig + SIG_OTS_SIG_OFFSET,
735 MBEDTLS_LMS_SIG_LEN(ctx->params.type,
736 ctx->params.otstype) - SIG_OTS_SIG_OFFSET,
737 NULL);
738 if (ret != 0) {
739 return ret;
740 }
741
742 MBEDTLS_PUT_UINT32_BE(ctx->params.type, sig, SIG_TYPE_OFFSET(ctx->params.otstype));
743 MBEDTLS_PUT_UINT32_BE(q_leaf_identifier, sig, SIG_Q_LEAF_ID_OFFSET);
744
745 ret = get_merkle_path(ctx,
746 MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type) + q_leaf_identifier,
747 sig + SIG_PATH_OFFSET(ctx->params.otstype));
748 if (ret != 0) {
749 return ret;
750 }
751
752 if (sig_len != NULL) {
753 *sig_len = MBEDTLS_LMS_SIG_LEN(ctx->params.type, ctx->params.otstype);
754 }
755
756
757 return 0;
758 }
759
760 #endif /* defined(MBEDTLS_LMS_PRIVATE) */
761 #endif /* defined(MBEDTLS_LMS_C) */
762
