1 /* 2 * The LMS stateful-hash public-key signature scheme 3 * 4 * Copyright The Mbed TLS Contributors 5 * SPDX-License-Identifier: Apache-2.0 6 * 7 * Licensed under the Apache License, Version 2.0 (the "License"); you may 8 * not use this file except in compliance with the License. 9 * You may obtain a copy of the License at 10 * 11 * http://www.apache.org/licenses/LICENSE-2.0 12 * 13 * Unless required by applicable law or agreed to in writing, software 14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 16 * See the License for the specific language governing permissions and 17 * limitations under the License. 18 */ 19 20 /* 21 * The following sources were referenced in the design of this implementation 22 * of the LMS algorithm: 23 * 24 * [1] IETF RFC8554 25 * D. McGrew, M. Curcio, S.Fluhrer 26 * https://datatracker.ietf.org/doc/html/rfc8554 27 * 28 * [2] NIST Special Publication 800-208 29 * David A. Cooper et. al. 30 * https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-208.pdf 31 */ 32 33 #include "common.h" 34 35 #if defined(MBEDTLS_LMS_C) 36 37 #include <string.h> 38 39 #include "lmots.h" 40 41 #include "psa/crypto.h" 42 #include "mbedtls/psa_util.h" 43 #include "mbedtls/lms.h" 44 #include "mbedtls/error.h" 45 #include "mbedtls/platform_util.h" 46 47 #include "mbedtls/platform.h" 48 49 #define PSA_TO_MBEDTLS_ERR(status) PSA_TO_MBEDTLS_ERR_LIST(status, \ 50 psa_to_lms_errors, \ 51 psa_generic_status_to_mbedtls) 52 53 #define SIG_Q_LEAF_ID_OFFSET (0) 54 #define SIG_OTS_SIG_OFFSET (SIG_Q_LEAF_ID_OFFSET + \ 55 MBEDTLS_LMOTS_Q_LEAF_ID_LEN) 56 #define SIG_TYPE_OFFSET(otstype) (SIG_OTS_SIG_OFFSET + \ 57 MBEDTLS_LMOTS_SIG_LEN(otstype)) 58 #define SIG_PATH_OFFSET(otstype) (SIG_TYPE_OFFSET(otstype) + \ 59 MBEDTLS_LMS_TYPE_LEN) 60 61 #define PUBLIC_KEY_TYPE_OFFSET (0) 62 #define PUBLIC_KEY_OTSTYPE_OFFSET (PUBLIC_KEY_TYPE_OFFSET + \ 63 MBEDTLS_LMS_TYPE_LEN) 64 #define PUBLIC_KEY_I_KEY_ID_OFFSET (PUBLIC_KEY_OTSTYPE_OFFSET + \ 65 MBEDTLS_LMOTS_TYPE_LEN) 66 #define PUBLIC_KEY_ROOT_NODE_OFFSET (PUBLIC_KEY_I_KEY_ID_OFFSET + \ 67 MBEDTLS_LMOTS_I_KEY_ID_LEN) 68 69 70 /* Currently only support H=10 */ 71 #define H_TREE_HEIGHT_MAX 10 72 #define MERKLE_TREE_NODE_AM(type) ((size_t) 1 << (MBEDTLS_LMS_H_TREE_HEIGHT(type) + 1u)) 73 #define MERKLE_TREE_LEAF_NODE_AM(type) ((size_t) 1 << MBEDTLS_LMS_H_TREE_HEIGHT(type)) 74 #define MERKLE_TREE_INTERNAL_NODE_AM(type) ((size_t) 1 << MBEDTLS_LMS_H_TREE_HEIGHT(type)) 75 76 #define D_CONST_LEN (2) 77 static const unsigned char D_LEAF_CONSTANT_BYTES[D_CONST_LEN] = { 0x82, 0x82 }; 78 static const unsigned char D_INTR_CONSTANT_BYTES[D_CONST_LEN] = { 0x83, 0x83 }; 79 80 81 /* Calculate the value of a leaf node of the Merkle tree (which is a hash of a 82 * public key and some other parameters like the leaf index). This function 83 * implements RFC8554 section 5.3, in the case where r >= 2^h. 84 * 85 * params The LMS parameter set, the underlying LMOTS 86 * parameter set, and I value which describe the key 87 * being used. 88 * 89 * pub_key The public key of the private whose index 90 * corresponds to the index of this leaf node. This 91 * is a hash output. 92 * 93 * r_node_idx The index of this node in the Merkle tree. Note 94 * that the root node of the Merkle tree is 95 * 1-indexed. 96 * 97 * out The output node value, which is a hash output. 98 */ 99 static int create_merkle_leaf_value(const mbedtls_lms_parameters_t *params, 100 unsigned char *pub_key, 101 unsigned int r_node_idx, 102 unsigned char *out) 103 { 104 psa_hash_operation_t op; 105 psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; 106 size_t output_hash_len; 107 unsigned char r_node_idx_bytes[4]; 108 109 op = psa_hash_operation_init(); 110 status = psa_hash_setup(&op, PSA_ALG_SHA_256); 111 if (status != PSA_SUCCESS) { 112 goto exit; 113 } 114 115 status = psa_hash_update(&op, params->I_key_identifier, 116 MBEDTLS_LMOTS_I_KEY_ID_LEN); 117 if (status != PSA_SUCCESS) { 118 goto exit; 119 } 120 121 mbedtls_lms_unsigned_int_to_network_bytes(r_node_idx, 4, r_node_idx_bytes); 122 status = psa_hash_update(&op, r_node_idx_bytes, 4); 123 if (status != PSA_SUCCESS) { 124 goto exit; 125 } 126 127 status = psa_hash_update(&op, D_LEAF_CONSTANT_BYTES, D_CONST_LEN); 128 if (status != PSA_SUCCESS) { 129 goto exit; 130 } 131 132 status = psa_hash_update(&op, pub_key, 133 MBEDTLS_LMOTS_N_HASH_LEN(params->otstype)); 134 if (status != PSA_SUCCESS) { 135 goto exit; 136 } 137 138 status = psa_hash_finish(&op, out, MBEDTLS_LMS_M_NODE_BYTES(params->type), 139 &output_hash_len); 140 if (status != PSA_SUCCESS) { 141 goto exit; 142 } 143 144 exit: 145 psa_hash_abort(&op); 146 147 return PSA_TO_MBEDTLS_ERR(status); 148 } 149 150 /* Calculate the value of an internal node of the Merkle tree (which is a hash 151 * of a public key and some other parameters like the node index). This function 152 * implements RFC8554 section 5.3, in the case where r < 2^h. 153 * 154 * params The LMS parameter set, the underlying LMOTS 155 * parameter set, and I value which describe the key 156 * being used. 157 * 158 * left_node The value of the child of this node which is on 159 * the left-hand side. As with all nodes on the 160 * Merkle tree, this is a hash output. 161 * 162 * right_node The value of the child of this node which is on 163 * the right-hand side. As with all nodes on the 164 * Merkle tree, this is a hash output. 165 * 166 * r_node_idx The index of this node in the Merkle tree. Note 167 * that the root node of the Merkle tree is 168 * 1-indexed. 169 * 170 * out The output node value, which is a hash output. 171 */ 172 static int create_merkle_internal_value(const mbedtls_lms_parameters_t *params, 173 const unsigned char *left_node, 174 const unsigned char *right_node, 175 unsigned int r_node_idx, 176 unsigned char *out) 177 { 178 psa_hash_operation_t op; 179 psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; 180 size_t output_hash_len; 181 unsigned char r_node_idx_bytes[4]; 182 183 op = psa_hash_operation_init(); 184 status = psa_hash_setup(&op, PSA_ALG_SHA_256); 185 if (status != PSA_SUCCESS) { 186 goto exit; 187 } 188 189 status = psa_hash_update(&op, params->I_key_identifier, 190 MBEDTLS_LMOTS_I_KEY_ID_LEN); 191 if (status != PSA_SUCCESS) { 192 goto exit; 193 } 194 195 mbedtls_lms_unsigned_int_to_network_bytes(r_node_idx, 4, r_node_idx_bytes); 196 status = psa_hash_update(&op, r_node_idx_bytes, 4); 197 if (status != PSA_SUCCESS) { 198 goto exit; 199 } 200 201 status = psa_hash_update(&op, D_INTR_CONSTANT_BYTES, D_CONST_LEN); 202 if (status != PSA_SUCCESS) { 203 goto exit; 204 } 205 206 status = psa_hash_update(&op, left_node, 207 MBEDTLS_LMS_M_NODE_BYTES(params->type)); 208 if (status != PSA_SUCCESS) { 209 goto exit; 210 } 211 212 status = psa_hash_update(&op, right_node, 213 MBEDTLS_LMS_M_NODE_BYTES(params->type)); 214 if (status != PSA_SUCCESS) { 215 goto exit; 216 } 217 218 status = psa_hash_finish(&op, out, MBEDTLS_LMS_M_NODE_BYTES(params->type), 219 &output_hash_len); 220 if (status != PSA_SUCCESS) { 221 goto exit; 222 } 223 224 exit: 225 psa_hash_abort(&op); 226 227 return PSA_TO_MBEDTLS_ERR(status); 228 } 229 230 void mbedtls_lms_public_init(mbedtls_lms_public_t *ctx) 231 { 232 memset(ctx, 0, sizeof(*ctx)); 233 } 234 235 void mbedtls_lms_public_free(mbedtls_lms_public_t *ctx) 236 { 237 mbedtls_platform_zeroize(ctx, sizeof(*ctx)); 238 } 239 240 int mbedtls_lms_import_public_key(mbedtls_lms_public_t *ctx, 241 const unsigned char *key, size_t key_size) 242 { 243 mbedtls_lms_algorithm_type_t type; 244 mbedtls_lmots_algorithm_type_t otstype; 245 246 type = mbedtls_lms_network_bytes_to_unsigned_int(MBEDTLS_LMS_TYPE_LEN, 247 key + PUBLIC_KEY_TYPE_OFFSET); 248 if (type != MBEDTLS_LMS_SHA256_M32_H10) { 249 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA; 250 } 251 ctx->params.type = type; 252 253 if (key_size != MBEDTLS_LMS_PUBLIC_KEY_LEN(ctx->params.type)) { 254 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA; 255 } 256 257 otstype = mbedtls_lms_network_bytes_to_unsigned_int(MBEDTLS_LMOTS_TYPE_LEN, 258 key + PUBLIC_KEY_OTSTYPE_OFFSET); 259 if (otstype != MBEDTLS_LMOTS_SHA256_N32_W8) { 260 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA; 261 } 262 ctx->params.otstype = otstype; 263 264 memcpy(ctx->params.I_key_identifier, 265 key + PUBLIC_KEY_I_KEY_ID_OFFSET, 266 MBEDTLS_LMOTS_I_KEY_ID_LEN); 267 memcpy(ctx->T_1_pub_key, key + PUBLIC_KEY_ROOT_NODE_OFFSET, 268 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type)); 269 270 ctx->have_public_key = 1; 271 272 return 0; 273 } 274 275 int mbedtls_lms_export_public_key(const mbedtls_lms_public_t *ctx, 276 unsigned char *key, 277 size_t key_size, size_t *key_len) 278 { 279 if (key_size < MBEDTLS_LMS_PUBLIC_KEY_LEN(ctx->params.type)) { 280 return MBEDTLS_ERR_LMS_BUFFER_TOO_SMALL; 281 } 282 283 if (!ctx->have_public_key) { 284 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA; 285 } 286 287 mbedtls_lms_unsigned_int_to_network_bytes( 288 ctx->params.type, 289 MBEDTLS_LMS_TYPE_LEN, key + PUBLIC_KEY_TYPE_OFFSET); 290 mbedtls_lms_unsigned_int_to_network_bytes(ctx->params.otstype, 291 MBEDTLS_LMOTS_TYPE_LEN, 292 key + PUBLIC_KEY_OTSTYPE_OFFSET); 293 memcpy(key + PUBLIC_KEY_I_KEY_ID_OFFSET, 294 ctx->params.I_key_identifier, 295 MBEDTLS_LMOTS_I_KEY_ID_LEN); 296 memcpy(key +PUBLIC_KEY_ROOT_NODE_OFFSET, 297 ctx->T_1_pub_key, 298 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type)); 299 300 if (key_len != NULL) { 301 *key_len = MBEDTLS_LMS_PUBLIC_KEY_LEN(ctx->params.type); 302 } 303 304 return 0; 305 } 306 307 int mbedtls_lms_verify(const mbedtls_lms_public_t *ctx, 308 const unsigned char *msg, size_t msg_size, 309 const unsigned char *sig, size_t sig_size) 310 { 311 unsigned int q_leaf_identifier; 312 unsigned char Kc_candidate_ots_pub_key[MBEDTLS_LMOTS_N_HASH_LEN_MAX]; 313 unsigned char Tc_candidate_root_node[MBEDTLS_LMS_M_NODE_BYTES_MAX]; 314 unsigned int height; 315 unsigned int curr_node_id; 316 unsigned int parent_node_id; 317 const unsigned char *left_node; 318 const unsigned char *right_node; 319 mbedtls_lmots_parameters_t ots_params; 320 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 321 322 if (!ctx->have_public_key) { 323 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA; 324 } 325 326 if (ctx->params.type 327 != MBEDTLS_LMS_SHA256_M32_H10) { 328 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA; 329 } 330 331 if (ctx->params.otstype 332 != MBEDTLS_LMOTS_SHA256_N32_W8) { 333 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA; 334 } 335 336 if (sig_size != MBEDTLS_LMS_SIG_LEN(ctx->params.type, ctx->params.otstype)) { 337 return MBEDTLS_ERR_LMS_VERIFY_FAILED; 338 } 339 340 if (sig_size < SIG_OTS_SIG_OFFSET + MBEDTLS_LMOTS_TYPE_LEN) { 341 return MBEDTLS_ERR_LMS_VERIFY_FAILED; 342 } 343 344 if (mbedtls_lms_network_bytes_to_unsigned_int(MBEDTLS_LMOTS_TYPE_LEN, 345 sig + SIG_OTS_SIG_OFFSET + 346 MBEDTLS_LMOTS_SIG_TYPE_OFFSET) 347 != MBEDTLS_LMOTS_SHA256_N32_W8) { 348 return MBEDTLS_ERR_LMS_VERIFY_FAILED; 349 } 350 351 if (sig_size < SIG_TYPE_OFFSET(ctx->params.otstype) + MBEDTLS_LMS_TYPE_LEN) { 352 return MBEDTLS_ERR_LMS_VERIFY_FAILED; 353 } 354 355 if (mbedtls_lms_network_bytes_to_unsigned_int(MBEDTLS_LMS_TYPE_LEN, 356 sig + SIG_TYPE_OFFSET(ctx->params.otstype)) 357 != MBEDTLS_LMS_SHA256_M32_H10) { 358 return MBEDTLS_ERR_LMS_VERIFY_FAILED; 359 } 360 361 362 q_leaf_identifier = mbedtls_lms_network_bytes_to_unsigned_int( 363 MBEDTLS_LMOTS_Q_LEAF_ID_LEN, sig + SIG_Q_LEAF_ID_OFFSET); 364 365 if (q_leaf_identifier >= MERKLE_TREE_LEAF_NODE_AM(ctx->params.type)) { 366 return MBEDTLS_ERR_LMS_VERIFY_FAILED; 367 } 368 369 memcpy(ots_params.I_key_identifier, 370 ctx->params.I_key_identifier, 371 MBEDTLS_LMOTS_I_KEY_ID_LEN); 372 mbedtls_lms_unsigned_int_to_network_bytes(q_leaf_identifier, 373 MBEDTLS_LMOTS_Q_LEAF_ID_LEN, 374 ots_params.q_leaf_identifier); 375 ots_params.type = ctx->params.otstype; 376 377 ret = mbedtls_lmots_calculate_public_key_candidate(&ots_params, 378 msg, 379 msg_size, 380 sig + SIG_OTS_SIG_OFFSET, 381 MBEDTLS_LMOTS_SIG_LEN(ctx->params.otstype), 382 Kc_candidate_ots_pub_key, 383 sizeof(Kc_candidate_ots_pub_key), 384 NULL); 385 if (ret != 0) { 386 return MBEDTLS_ERR_LMS_VERIFY_FAILED; 387 } 388 389 create_merkle_leaf_value( 390 &ctx->params, 391 Kc_candidate_ots_pub_key, 392 MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type) + q_leaf_identifier, 393 Tc_candidate_root_node); 394 395 curr_node_id = MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type) + 396 q_leaf_identifier; 397 398 for (height = 0; height < MBEDTLS_LMS_H_TREE_HEIGHT(ctx->params.type); 399 height++) { 400 parent_node_id = curr_node_id / 2; 401 402 /* Left/right node ordering matters for the hash */ 403 if (curr_node_id & 1) { 404 left_node = sig + SIG_PATH_OFFSET(ctx->params.otstype) + 405 height * MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type); 406 right_node = Tc_candidate_root_node; 407 } else { 408 left_node = Tc_candidate_root_node; 409 right_node = sig + SIG_PATH_OFFSET(ctx->params.otstype) + 410 height * MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type); 411 } 412 413 create_merkle_internal_value(&ctx->params, left_node, right_node, 414 parent_node_id, Tc_candidate_root_node); 415 416 curr_node_id /= 2; 417 } 418 419 if (memcmp(Tc_candidate_root_node, ctx->T_1_pub_key, 420 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type))) { 421 return MBEDTLS_ERR_LMS_VERIFY_FAILED; 422 } 423 424 return 0; 425 } 426 427 #if defined(MBEDTLS_LMS_PRIVATE) 428 429 /* Calculate a full Merkle tree based on a private key. This function 430 * implements RFC8554 section 5.3, and is used to generate a public key (as the 431 * public key is the root node of the Merkle tree). 432 * 433 * ctx The LMS private context, containing a parameter 434 * set and private key material consisting of both 435 * public and private OTS. 436 * 437 * tree The output tree, which is 2^(H + 1) hash outputs. 438 * In the case of H=10 we have 2048 tree nodes (of 439 * which 1024 of them are leaf nodes). Note that 440 * because the Merkle tree root is 1-indexed, the 0 441 * index tree node is never used. 442 */ 443 static int calculate_merkle_tree(const mbedtls_lms_private_t *ctx, 444 unsigned char *tree) 445 { 446 unsigned int priv_key_idx; 447 unsigned int r_node_idx; 448 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 449 450 /* First create the leaf nodes, in ascending order */ 451 for (priv_key_idx = 0; 452 priv_key_idx < MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type); 453 priv_key_idx++) { 454 r_node_idx = MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type) + priv_key_idx; 455 456 ret = create_merkle_leaf_value(&ctx->params, 457 ctx->ots_public_keys[priv_key_idx].public_key, 458 r_node_idx, 459 &tree[r_node_idx * MBEDTLS_LMS_M_NODE_BYTES( 460 ctx->params.type)]); 461 if (ret != 0) { 462 return ret; 463 } 464 } 465 466 /* Then the internal nodes, in reverse order so that we can guarantee the 467 * parent has been created */ 468 for (r_node_idx = MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type) - 1; 469 r_node_idx > 0; 470 r_node_idx--) { 471 ret = create_merkle_internal_value(&ctx->params, 472 &tree[(r_node_idx * 2) * 473 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type)], 474 &tree[(r_node_idx * 2 + 1) * 475 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type)], 476 r_node_idx, 477 &tree[r_node_idx * 478 MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type)]); 479 if (ret != 0) { 480 return ret; 481 } 482 } 483 484 return 0; 485 } 486 487 /* Calculate a path from a leaf node of the Merkle tree to the root of the tree, 488 * and return the full path. This function implements RFC8554 section 5.4.1, as 489 * the Merkle path is the main component of an LMS signature. 490 * 491 * ctx The LMS private context, containing a parameter 492 * set and private key material consisting of both 493 * public and private OTS. 494 * 495 * leaf_node_id Which leaf node to calculate the path from. 496 * 497 * path The output path, which is H hash outputs. 498 */ 499 static int get_merkle_path(mbedtls_lms_private_t *ctx, 500 unsigned int leaf_node_id, 501 unsigned char *path) 502 { 503 const size_t node_bytes = MBEDTLS_LMS_M_NODE_BYTES(ctx->params.type); 504 unsigned int curr_node_id = leaf_node_id; 505 unsigned int adjacent_node_id; 506 unsigned char *tree = NULL; 507 unsigned int height; 508 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 509 510 tree = mbedtls_calloc(MERKLE_TREE_NODE_AM(ctx->params.type), 511 node_bytes); 512 if (tree == NULL) { 513 return MBEDTLS_ERR_LMS_ALLOC_FAILED; 514 } 515 516 ret = calculate_merkle_tree(ctx, tree); 517 if (ret != 0) { 518 goto exit; 519 } 520 521 for (height = 0; height < MBEDTLS_LMS_H_TREE_HEIGHT(ctx->params.type); 522 height++) { 523 adjacent_node_id = curr_node_id ^ 1; 524 525 memcpy(&path[height * node_bytes], 526 &tree[adjacent_node_id * node_bytes], node_bytes); 527 528 curr_node_id >>= 1; 529 } 530 531 ret = 0; 532 533 exit: 534 mbedtls_platform_zeroize(tree, node_bytes * 535 MERKLE_TREE_NODE_AM(ctx->params.type)); 536 mbedtls_free(tree); 537 538 return ret; 539 } 540 541 void mbedtls_lms_private_init(mbedtls_lms_private_t *ctx) 542 { 543 memset(ctx, 0, sizeof(*ctx)); 544 } 545 546 void mbedtls_lms_private_free(mbedtls_lms_private_t *ctx) 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 } 569 570 571 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 } 653 654 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(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_platform_zeroize(tree, node_bytes * 698 MERKLE_TREE_NODE_AM(priv_ctx->params.type)); 699 mbedtls_free(tree); 700 701 return ret; 702 } 703 704 705 int mbedtls_lms_sign(mbedtls_lms_private_t *ctx, 706 int (*f_rng)(void *, unsigned char *, size_t), 707 void *p_rng, const unsigned char *msg, 708 unsigned int msg_size, unsigned char *sig, size_t sig_size, 709 size_t *sig_len) 710 { 711 uint32_t q_leaf_identifier; 712 int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; 713 714 if (!ctx->have_private_key) { 715 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA; 716 } 717 718 if (sig_size < MBEDTLS_LMS_SIG_LEN(ctx->params.type, ctx->params.otstype)) { 719 return MBEDTLS_ERR_LMS_BUFFER_TOO_SMALL; 720 } 721 722 if (ctx->params.type != MBEDTLS_LMS_SHA256_M32_H10) { 723 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA; 724 } 725 726 if (ctx->params.otstype 727 != MBEDTLS_LMOTS_SHA256_N32_W8) { 728 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA; 729 } 730 731 if (ctx->q_next_usable_key >= MERKLE_TREE_LEAF_NODE_AM(ctx->params.type)) { 732 return MBEDTLS_ERR_LMS_OUT_OF_PRIVATE_KEYS; 733 } 734 735 736 q_leaf_identifier = ctx->q_next_usable_key; 737 /* This new value must _always_ be written back to the disk before the 738 * signature is returned. 739 */ 740 ctx->q_next_usable_key += 1; 741 742 if (MBEDTLS_LMS_SIG_LEN(ctx->params.type, ctx->params.otstype) 743 < SIG_OTS_SIG_OFFSET) { 744 return MBEDTLS_ERR_LMS_BAD_INPUT_DATA; 745 } 746 747 ret = mbedtls_lmots_sign(&ctx->ots_private_keys[q_leaf_identifier], 748 f_rng, 749 p_rng, 750 msg, 751 msg_size, 752 sig + SIG_OTS_SIG_OFFSET, 753 MBEDTLS_LMS_SIG_LEN(ctx->params.type, 754 ctx->params.otstype) - SIG_OTS_SIG_OFFSET, 755 NULL); 756 if (ret != 0) { 757 return ret; 758 } 759 760 mbedtls_lms_unsigned_int_to_network_bytes(ctx->params.type, 761 MBEDTLS_LMS_TYPE_LEN, 762 sig + SIG_TYPE_OFFSET(ctx->params.otstype)); 763 mbedtls_lms_unsigned_int_to_network_bytes(q_leaf_identifier, 764 MBEDTLS_LMOTS_Q_LEAF_ID_LEN, 765 sig + SIG_Q_LEAF_ID_OFFSET); 766 767 ret = get_merkle_path(ctx, 768 MERKLE_TREE_INTERNAL_NODE_AM(ctx->params.type) + q_leaf_identifier, 769 sig + SIG_PATH_OFFSET(ctx->params.otstype)); 770 if (ret != 0) { 771 return ret; 772 } 773 774 if (sig_len != NULL) { 775 *sig_len = MBEDTLS_LMS_SIG_LEN(ctx->params.type, ctx->params.otstype); 776 } 777 778 779 return 0; 780 } 781 782 #endif /* defined(MBEDTLS_LMS_PRIVATE) */ 783 #endif /* defined(MBEDTLS_LMS_C) */ 784