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| 1 | +// |
| 2 | +// C implementation of SMT verification: |
| 3 | +// https://github.com/nervosnetwork/sparse-merkle-tree |
| 4 | +// |
| 5 | +// origin from: |
| 6 | +// https://github.com/nervosnetwork/godwoken/blob/6c9b92b9b06068a8678864b35a3272545ed7909e/c/gw_smt.h#L1 |
| 7 | +#ifndef _CKB_SPARSE_MERKLE_TREE_H_ |
| 8 | +#define _CKB_SPARSE_MERKLE_TREE_H_ |
| 9 | + |
| 10 | +// users can define a new stack size if needed |
| 11 | +#ifndef SMT_STACK_SIZE |
| 12 | +#define SMT_STACK_SIZE 257 |
| 13 | +#endif |
| 14 | + |
| 15 | +#define SMT_KEY_BYTES 32 |
| 16 | +#define SMT_VALUE_BYTES 32 |
| 17 | + |
| 18 | +const uint8_t SMT_ZERO[SMT_VALUE_BYTES] = {0}; |
| 19 | + |
| 20 | +enum SMTErrorCode { |
| 21 | + // SMT |
| 22 | + ERROR_INSUFFICIENT_CAPACITY = 80, |
| 23 | + ERROR_NOT_FOUND, |
| 24 | + ERROR_INVALID_STACK, |
| 25 | + ERROR_INVALID_SIBLING, |
| 26 | + ERROR_INVALID_PROOF |
| 27 | +}; |
| 28 | + |
| 29 | +/* Key Value Pairs */ |
| 30 | +typedef struct { |
| 31 | + uint8_t key[SMT_KEY_BYTES]; |
| 32 | + uint8_t value[SMT_VALUE_BYTES]; |
| 33 | + uint32_t order; |
| 34 | +} smt_pair_t; |
| 35 | + |
| 36 | +typedef struct { |
| 37 | + smt_pair_t *pairs; |
| 38 | + uint32_t len; |
| 39 | + uint32_t capacity; |
| 40 | +} smt_state_t; |
| 41 | + |
| 42 | +void smt_state_init(smt_state_t *state, smt_pair_t *buffer, uint32_t capacity) { |
| 43 | + state->pairs = buffer; |
| 44 | + state->len = 0; |
| 45 | + state->capacity = capacity; |
| 46 | +} |
| 47 | + |
| 48 | +int smt_state_insert(smt_state_t *state, const uint8_t *key, |
| 49 | + const uint8_t *value) { |
| 50 | + if (state->len < state->capacity) { |
| 51 | + /* shortcut, append at end */ |
| 52 | + memcpy(state->pairs[state->len].key, key, SMT_KEY_BYTES); |
| 53 | + memcpy(state->pairs[state->len].value, value, SMT_KEY_BYTES); |
| 54 | + state->len++; |
| 55 | + return 0; |
| 56 | + } |
| 57 | + |
| 58 | + /* Find a matched key and overwritten it */ |
| 59 | + int32_t i = state->len - 1; |
| 60 | + for (; i >= 0; i--) { |
| 61 | + if (memcmp(key, state->pairs[i].key, SMT_KEY_BYTES) == 0) { |
| 62 | + break; |
| 63 | + } |
| 64 | + } |
| 65 | + |
| 66 | + if (i < 0) { |
| 67 | + return ERROR_INSUFFICIENT_CAPACITY; |
| 68 | + } |
| 69 | + |
| 70 | + memcpy(state->pairs[i].value, value, SMT_VALUE_BYTES); |
| 71 | + return 0; |
| 72 | +} |
| 73 | + |
| 74 | +int smt_state_fetch(smt_state_t *state, const uint8_t *key, uint8_t *value) { |
| 75 | + int32_t i = state->len - 1; |
| 76 | + for (; i >= 0; i--) { |
| 77 | + if (memcmp(key, state->pairs[i].key, SMT_KEY_BYTES) == 0) { |
| 78 | + memcpy(value, state->pairs[i].value, SMT_VALUE_BYTES); |
| 79 | + return 0; |
| 80 | + } |
| 81 | + } |
| 82 | + return ERROR_NOT_FOUND; |
| 83 | +} |
| 84 | + |
| 85 | +int _smt_pair_cmp(const void *a, const void *b) { |
| 86 | + const smt_pair_t *pa = (const smt_pair_t *)a; |
| 87 | + const smt_pair_t *pb = (const smt_pair_t *)b; |
| 88 | + |
| 89 | + for (int i = SMT_KEY_BYTES - 1; i >= 0; i--) { |
| 90 | + int cmp_result = pa->key[i] - pb->key[i]; |
| 91 | + if (cmp_result != 0) { |
| 92 | + return cmp_result; |
| 93 | + } |
| 94 | + } |
| 95 | + return pa->order - pb->order; |
| 96 | +} |
| 97 | + |
| 98 | +void smt_state_normalize(smt_state_t *state) { |
| 99 | + for (uint32_t i = 0; i < state->len; i++) { |
| 100 | + state->pairs[i].order = state->len - i; |
| 101 | + } |
| 102 | + qsort(state->pairs, state->len, sizeof(smt_pair_t), _smt_pair_cmp); |
| 103 | + /* Remove duplicate ones */ |
| 104 | + int32_t sorted = 0, next = 0; |
| 105 | + while (next < (int32_t)state->len) { |
| 106 | + int32_t item_index = next++; |
| 107 | + while (next < (int32_t)state->len && |
| 108 | + memcmp(state->pairs[item_index].key, state->pairs[next].key, |
| 109 | + SMT_KEY_BYTES) == 0) { |
| 110 | + next++; |
| 111 | + } |
| 112 | + if (item_index != sorted) { |
| 113 | + memcpy(state->pairs[sorted].key, state->pairs[item_index].key, |
| 114 | + SMT_KEY_BYTES); |
| 115 | + memcpy(state->pairs[sorted].value, state->pairs[item_index].value, |
| 116 | + SMT_VALUE_BYTES); |
| 117 | + } |
| 118 | + sorted++; |
| 119 | + } |
| 120 | + state->len = sorted; |
| 121 | +} |
| 122 | + |
| 123 | +/* SMT */ |
| 124 | + |
| 125 | +int _smt_get_bit(const uint8_t *data, int offset) { |
| 126 | + int byte_pos = offset / 8; |
| 127 | + int bit_pos = offset % 8; |
| 128 | + return ((data[byte_pos] >> bit_pos) & 1) != 0; |
| 129 | +} |
| 130 | + |
| 131 | +void _smt_set_bit(uint8_t *data, int offset) { |
| 132 | + int byte_pos = offset / 8; |
| 133 | + int bit_pos = offset % 8; |
| 134 | + data[byte_pos] |= 1 << bit_pos; |
| 135 | +} |
| 136 | + |
| 137 | +void _smt_clear_bit(uint8_t *data, int offset) { |
| 138 | + int byte_pos = offset / 8; |
| 139 | + int bit_pos = offset % 8; |
| 140 | + data[byte_pos] &= (uint8_t)(~(1 << bit_pos)); |
| 141 | +} |
| 142 | + |
| 143 | +void _smt_copy_bits(uint8_t *source, int first_kept_bit) { |
| 144 | + int first_byte = first_kept_bit / 8; |
| 145 | + for (int i = 0; i < first_byte; i++) { |
| 146 | + source[i] = 0; |
| 147 | + } |
| 148 | + for (int i = first_byte * 8; i < first_kept_bit; i++) { |
| 149 | + _smt_clear_bit(source, i); |
| 150 | + } |
| 151 | +} |
| 152 | + |
| 153 | +void _smt_parent_path(uint8_t *key, uint8_t height) { |
| 154 | + if (height == 255) { |
| 155 | + memset(key, 0, 32); |
| 156 | + } else { |
| 157 | + _smt_copy_bits(key, height + 1); |
| 158 | + } |
| 159 | +} |
| 160 | + |
| 161 | +int _smt_zero_value(const uint8_t *value) { |
| 162 | + for (int i = 0; i < 32; i++) { |
| 163 | + if (value[i] != 0) { |
| 164 | + return 0; |
| 165 | + } |
| 166 | + } |
| 167 | + return 1; |
| 168 | +} |
| 169 | + |
| 170 | +/* Notice that output might collide with one of lhs, or rhs */ |
| 171 | +void _smt_merge(uint8_t height, const uint8_t *node_key, const uint8_t *lhs, |
| 172 | + const uint8_t *rhs, uint8_t *output) { |
| 173 | + if (_smt_zero_value(lhs) && _smt_zero_value(rhs)) { |
| 174 | + memcpy(output, SMT_ZERO, SMT_VALUE_BYTES); |
| 175 | + } else { |
| 176 | + blake2b_state blake2b_ctx; |
| 177 | + blake2b_init(&blake2b_ctx, 32); |
| 178 | + |
| 179 | + blake2b_update(&blake2b_ctx, &height, 1); |
| 180 | + blake2b_update(&blake2b_ctx, node_key, 32); |
| 181 | + blake2b_update(&blake2b_ctx, lhs, 32); |
| 182 | + blake2b_update(&blake2b_ctx, rhs, 32); |
| 183 | + |
| 184 | + blake2b_final(&blake2b_ctx, output, 32); |
| 185 | + } |
| 186 | +} |
| 187 | + |
| 188 | +/* |
| 189 | + * Theoretically, a stack size of x should be able to process as many as |
| 190 | + * 2 ** (x - 1) updates. In this case with a stack size of 32, we can deal |
| 191 | + * with 2 ** 31 == 2147483648 updates, which is more than enough. |
| 192 | + */ |
| 193 | +int smt_calculate_root(uint8_t *buffer, const smt_state_t *pairs, |
| 194 | + const uint8_t *proof, uint32_t proof_length) { |
| 195 | + uint8_t stack_keys[SMT_STACK_SIZE][SMT_KEY_BYTES]; |
| 196 | + uint8_t stack_values[SMT_STACK_SIZE][SMT_VALUE_BYTES]; |
| 197 | + uint16_t stack_heights[SMT_STACK_SIZE] = {0}; |
| 198 | + |
| 199 | + uint32_t proof_index = 0; |
| 200 | + uint32_t leave_index = 0; |
| 201 | + uint32_t stack_top = 0; |
| 202 | + |
| 203 | + while (proof_index < proof_length) { |
| 204 | + switch (proof[proof_index++]) { |
| 205 | + case 0x4C: { |
| 206 | + if (stack_top >= SMT_STACK_SIZE) { |
| 207 | + return ERROR_INVALID_STACK; |
| 208 | + } |
| 209 | + if (leave_index >= pairs->len) { |
| 210 | + return ERROR_INVALID_PROOF; |
| 211 | + } |
| 212 | + memcpy(stack_keys[stack_top], pairs->pairs[leave_index].key, |
| 213 | + SMT_KEY_BYTES); |
| 214 | + memcpy(stack_values[stack_top], pairs->pairs[leave_index].value, |
| 215 | + SMT_VALUE_BYTES); |
| 216 | + stack_heights[stack_top] = 0; |
| 217 | + stack_top++; |
| 218 | + leave_index++; |
| 219 | + } break; |
| 220 | + case 0x50: { |
| 221 | + if (stack_top == 0) { |
| 222 | + return ERROR_INVALID_STACK; |
| 223 | + } |
| 224 | + if (proof_index + 32 > proof_length) { |
| 225 | + return ERROR_INVALID_PROOF; |
| 226 | + } |
| 227 | + const uint8_t *sibling_node = &proof[proof_index]; |
| 228 | + proof_index += 32; |
| 229 | + uint8_t *key = stack_keys[stack_top - 1]; |
| 230 | + uint8_t *value = stack_values[stack_top - 1]; |
| 231 | + uint16_t height = stack_heights[stack_top - 1]; |
| 232 | + uint16_t *height_ptr = &stack_heights[stack_top - 1]; |
| 233 | + if (height > 255) { |
| 234 | + return ERROR_INVALID_PROOF; |
| 235 | + } |
| 236 | + uint8_t parent_key[SMT_KEY_BYTES]; |
| 237 | + memcpy(parent_key, key, SMT_KEY_BYTES); |
| 238 | + _smt_parent_path(parent_key, height); |
| 239 | + |
| 240 | + // push value |
| 241 | + if (_smt_get_bit(key, height)) { |
| 242 | + _smt_merge((uint8_t)height, parent_key, sibling_node, value, value); |
| 243 | + } else { |
| 244 | + _smt_merge((uint8_t)height, parent_key, value, sibling_node, value); |
| 245 | + } |
| 246 | + // push key |
| 247 | + _smt_parent_path(key, height); |
| 248 | + // push height |
| 249 | + *height_ptr = height + 1; |
| 250 | + } break; |
| 251 | + case 0x48: { |
| 252 | + if (stack_top < 2) { |
| 253 | + return ERROR_INVALID_STACK; |
| 254 | + } |
| 255 | + if (proof_index >= proof_length) { |
| 256 | + return ERROR_INVALID_PROOF; |
| 257 | + } |
| 258 | + uint16_t *height_a_ptr = &stack_heights[stack_top - 2]; |
| 259 | + |
| 260 | + uint16_t height_a = stack_heights[stack_top - 2]; |
| 261 | + uint8_t *key_a = stack_keys[stack_top - 2]; |
| 262 | + uint8_t *value_a = stack_values[stack_top - 2]; |
| 263 | + |
| 264 | + uint16_t height_b = stack_heights[stack_top - 1]; |
| 265 | + uint8_t *key_b = stack_keys[stack_top - 1]; |
| 266 | + uint8_t *value_b = stack_values[stack_top - 1]; |
| 267 | + stack_top -= 2; |
| 268 | + if (height_a != height_b) { |
| 269 | + return ERROR_INVALID_PROOF; |
| 270 | + } |
| 271 | + if (height_a > 255) { |
| 272 | + return ERROR_INVALID_PROOF; |
| 273 | + } |
| 274 | + uint8_t parent_key[SMT_KEY_BYTES]; |
| 275 | + memcpy(parent_key, key_a, SMT_KEY_BYTES); |
| 276 | + _smt_parent_path(parent_key, (uint8_t)height_a); |
| 277 | + |
| 278 | + // 2 keys should have same parent keys |
| 279 | + _smt_parent_path(key_b, (uint8_t)height_b); |
| 280 | + if (memcmp(parent_key, key_b, SMT_KEY_BYTES) != 0) { |
| 281 | + return ERROR_INVALID_PROOF; |
| 282 | + } |
| 283 | + // push value |
| 284 | + if (_smt_get_bit(key_a, height_a)) { |
| 285 | + _smt_merge(height_a, parent_key, value_b, value_a, value_a); |
| 286 | + } else { |
| 287 | + _smt_merge(height_a, parent_key, value_a, value_b, value_a); |
| 288 | + } |
| 289 | + // push key |
| 290 | + memcpy(key_a, parent_key, SMT_KEY_BYTES); |
| 291 | + // push height |
| 292 | + *height_a_ptr = height_a + 1; |
| 293 | + stack_top++; |
| 294 | + } break; |
| 295 | + case 0x4F: { |
| 296 | + if (stack_top < 1) { |
| 297 | + return ERROR_INVALID_STACK; |
| 298 | + } |
| 299 | + if (proof_index >= proof_length) { |
| 300 | + return ERROR_INVALID_PROOF; |
| 301 | + } |
| 302 | + uint16_t n = proof[proof_index]; |
| 303 | + proof_index++; |
| 304 | + uint16_t zero_count = 0; |
| 305 | + if (n == 0) { |
| 306 | + zero_count = 256; |
| 307 | + } else { |
| 308 | + zero_count = n; |
| 309 | + } |
| 310 | + uint16_t *base_height_ptr = &stack_heights[stack_top - 1]; |
| 311 | + uint16_t base_height = stack_heights[stack_top - 1]; |
| 312 | + uint8_t *key = stack_keys[stack_top - 1]; |
| 313 | + uint8_t *value = stack_values[stack_top - 1]; |
| 314 | + if (base_height > 255) { |
| 315 | + return ERROR_INVALID_PROOF; |
| 316 | + } |
| 317 | + uint8_t parent_key[SMT_KEY_BYTES]; |
| 318 | + memcpy(parent_key, key, SMT_KEY_BYTES); |
| 319 | + uint16_t height_u16 = base_height; |
| 320 | + for (uint16_t idx = 0; idx < zero_count; idx++) { |
| 321 | + height_u16 = base_height + idx; |
| 322 | + if (height_u16 > 255) { |
| 323 | + return ERROR_INVALID_PROOF; |
| 324 | + } |
| 325 | + // the following code can be omitted: |
| 326 | + // memcpy(parent_key, key, SMT_KEY_BYTES); |
| 327 | + // A key's parent's parent can be calculated from parent. |
| 328 | + // it's not needed to do it from scratch. |
| 329 | + // Make sure height_u16 is in increase order |
| 330 | + _smt_parent_path(parent_key, (uint8_t)height_u16); |
| 331 | + // push value |
| 332 | + if (_smt_get_bit(key, (uint8_t)height_u16)) { |
| 333 | + _smt_merge((uint8_t)height_u16, parent_key, SMT_ZERO, value, value); |
| 334 | + } else { |
| 335 | + _smt_merge((uint8_t)height_u16, parent_key, value, SMT_ZERO, value); |
| 336 | + } |
| 337 | + } |
| 338 | + // push key |
| 339 | + memcpy(key, parent_key, SMT_KEY_BYTES); |
| 340 | + // push height |
| 341 | + *base_height_ptr = height_u16 + 1; |
| 342 | + } break; |
| 343 | + default: |
| 344 | + return ERROR_INVALID_PROOF; |
| 345 | + } |
| 346 | + } |
| 347 | + if (stack_top != 1) { |
| 348 | + return ERROR_INVALID_STACK; |
| 349 | + } |
| 350 | + if (stack_heights[0] != 256) { |
| 351 | + return ERROR_INVALID_PROOF; |
| 352 | + } |
| 353 | + /* All leaves must be used */ |
| 354 | + if (leave_index != pairs->len) { |
| 355 | + return ERROR_INVALID_PROOF; |
| 356 | + } |
| 357 | + |
| 358 | + memcpy(buffer, stack_values[0], 32); |
| 359 | + return 0; |
| 360 | +} |
| 361 | + |
| 362 | +int smt_verify(const uint8_t *hash, const smt_state_t *state, |
| 363 | + const uint8_t *proof, uint32_t proof_length) { |
| 364 | + uint8_t buffer[32]; |
| 365 | + int ret = smt_calculate_root(buffer, state, proof, proof_length); |
| 366 | + if (ret != 0) { |
| 367 | + return ret; |
| 368 | + } |
| 369 | + if (memcmp(buffer, hash, 32) != 0) { |
| 370 | + return ERROR_INVALID_PROOF; |
| 371 | + } |
| 372 | + return 0; |
| 373 | +} |
| 374 | + |
| 375 | +#endif |
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