Skip to content

Commit b62b67e

Browse files
meshcollidermeshcollider
committed
Add Bech32 error location function
1 parent 0b06e72 commit b62b67e

File tree

4 files changed

+326
-15
lines changed

4 files changed

+326
-15
lines changed

‎src/bech32.cpp

Lines changed: 311 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -30,6 +30,155 @@ const int8_t CHARSET_REV[128] = {
3030
1, 0, 3, 16, 11, 28, 12, 14, 6, 4, 2, -1, -1, -1, -1, -1
3131
};
3232

33+
34+
const int16_t GF1024_EXP[] = {
35+
1, 303, 635, 446, 997, 640, 121, 142, 959, 420, 350, 438, 166, 39, 543,
36+
335, 831, 691, 117, 632, 719, 97, 107, 374, 558, 797, 54, 150, 858, 877,
37+
724, 1013, 294, 23, 354, 61, 164, 633, 992, 538, 469, 659, 174, 868, 184,
38+
809, 766, 563, 866, 851, 257, 520, 45, 770, 535, 524, 408, 213, 436, 760,
39+
472, 330, 933, 799, 616, 361, 15, 391, 756, 814, 58, 608, 554, 680, 993,
40+
821, 942, 813, 843, 484, 193, 935, 321, 919, 572, 741, 423, 559, 562,
41+
589, 296, 191, 493, 685, 891, 665, 435, 60, 395, 2, 606, 511, 853, 746,
42+
32, 219, 284, 631, 840, 661, 837, 332, 78, 311, 670, 887, 111, 195, 505,
43+
190, 194, 214, 709, 380, 819, 69, 261, 957, 1018, 161, 739, 588, 7, 708,
44+
83, 328, 507, 736, 317, 899, 47, 348, 1000, 345, 882, 245, 367, 996, 943,
45+
514, 304, 90, 804, 295, 312, 793, 387, 833, 249, 921, 660, 618, 823, 496,
46+
722, 30, 782, 225, 892, 93, 480, 372, 112, 738, 867, 636, 890, 950, 968,
47+
386, 622, 642, 551, 369, 234, 846, 382, 365, 442, 592, 343, 986, 122,
48+
1023, 59, 847, 81, 790, 4, 437, 983, 931, 244, 64, 415, 529, 487, 944,
49+
35, 938, 664, 156, 583, 53, 999, 222, 390, 987, 341, 388, 389, 170, 721,
50+
879, 138, 522, 627, 765, 322, 230, 440, 14, 168, 143, 656, 991, 224, 595,
51+
550, 94, 657, 752, 667, 1005, 451, 734, 744, 638, 292, 585, 157, 872,
52+
590, 601, 827, 774, 930, 475, 571, 33, 500, 871, 969, 173, 21, 828, 450,
53+
1009, 147, 960, 705, 201, 228, 998, 497, 1021, 613, 688, 772, 508, 36,
54+
366, 715, 468, 956, 725, 730, 861, 425, 647, 701, 221, 759, 95, 958, 139,
55+
805, 8, 835, 679, 614, 449, 128, 791, 299, 974, 617, 70, 628, 57, 273,
56+
430, 67, 750, 405, 780, 703, 643, 776, 778, 340, 171, 1022, 276, 308,
57+
495, 243, 644, 460, 857, 28, 336, 286, 41, 695, 448, 431, 364, 149, 43,
58+
233, 63, 762, 902, 181, 240, 501, 584, 434, 275, 1008, 444, 443, 895,
59+
812, 612, 927, 383, 66, 961, 1006, 690, 346, 3, 881, 900, 747, 271, 672,
60+
162, 402, 456, 748, 971, 755, 490, 105, 808, 977, 72, 732, 182, 897, 625,
61+
163, 189, 947, 850, 46, 115, 403, 231, 151, 629, 278, 874, 16, 934, 110,
62+
492, 898, 256, 807, 598, 700, 498, 140, 481, 91, 523, 860, 134, 252, 771,
63+
824, 119, 38, 816, 820, 641, 342, 757, 513, 577, 990, 463, 40, 920, 955,
64+
17, 649, 533, 82, 103, 896, 862, 728, 259, 86, 466, 87, 253, 556, 323,
65+
457, 963, 432, 845, 527, 745, 849, 863, 1015, 888, 488, 567, 727, 132,
66+
674, 764, 109, 669, 6, 1003, 552, 246, 542, 96, 324, 781, 912, 248, 694,
67+
239, 980, 210, 880, 683, 144, 177, 325, 546, 491, 326, 339, 623, 941, 92,
68+
207, 783, 462, 263, 483, 517, 1012, 9, 620, 220, 984, 548, 512, 878, 421,
69+
113, 973, 280, 962, 159, 310, 945, 268, 465, 806, 889, 199, 76, 873, 865,
70+
34, 645, 227, 290, 418, 693, 926, 80, 569, 639, 11, 50, 291, 141, 206,
71+
544, 949, 185, 518, 133, 909, 135, 467, 376, 646, 914, 678, 841, 954,
72+
318, 242, 939, 951, 743, 1017, 976, 359, 167, 264, 100, 241, 218, 51, 12,
73+
758, 368, 453, 309, 192, 648, 826, 553, 473, 101, 478, 673, 397, 1001,
74+
118, 265, 331, 650, 356, 982, 652, 655, 510, 634, 145, 414, 830, 924,
75+
526, 966, 298, 737, 18, 504, 401, 697, 360, 288, 1020, 842, 203, 698,
76+
537, 676, 279, 581, 619, 536, 907, 876, 1019, 398, 152, 1010, 994, 68,
77+
42, 454, 580, 836, 99, 565, 137, 379, 503, 22, 77, 582, 282, 412, 352,
78+
611, 347, 300, 266, 570, 270, 911, 729, 44, 557, 108, 946, 637, 597, 461,
79+
630, 615, 238, 763, 681, 718, 334, 528, 200, 459, 413, 79, 24, 229, 713,
80+
906, 579, 384, 48, 893, 370, 923, 202, 917, 98, 794, 754, 197, 530, 662,
81+
52, 712, 677, 56, 62, 981, 509, 267, 789, 885, 561, 316, 684, 596, 226,
82+
13, 985, 779, 123, 720, 576, 753, 948, 406, 125, 315, 104, 519, 426, 502,
83+
313, 566, 1016, 767, 796, 281, 749, 740, 136, 84, 908, 424, 936, 198,
84+
355, 274, 735, 967, 5, 154, 428, 541, 785, 704, 486, 671, 600, 532, 381,
85+
540, 574, 187, 88, 378, 216, 621, 499, 419, 922, 485, 494, 476, 255, 114,
86+
188, 668, 297, 400, 918, 787, 158, 25, 458, 178, 564, 422, 768, 73, 1011,
87+
717, 575, 404, 547, 196, 829, 237, 394, 301, 37, 65, 176, 106, 89, 85,
88+
675, 979, 534, 803, 995, 363, 593, 120, 417, 452, 26, 699, 822, 223, 169,
89+
416, 235, 609, 773, 211, 607, 208, 302, 852, 965, 603, 357, 761, 247,
90+
817, 539, 250, 232, 272, 129, 568, 848, 624, 396, 710, 525, 183, 686, 10,
91+
285, 856, 307, 811, 160, 972, 55, 441, 289, 723, 305, 373, 351, 153, 733,
92+
409, 506, 975, 838, 573, 970, 988, 913, 471, 205, 337, 49, 594, 777, 549,
93+
815, 277, 27, 916, 333, 353, 844, 800, 146, 751, 186, 375, 769, 358, 392,
94+
883, 474, 788, 602, 74, 130, 329, 212, 155, 131, 102, 687, 293, 870, 742,
95+
726, 427, 217, 834, 904, 29, 127, 869, 407, 338, 832, 470, 482, 810, 399,
96+
439, 393, 604, 929, 682, 447, 714, 251, 455, 875, 319, 477, 464, 521,
97+
258, 377, 937, 489, 792, 172, 314, 327, 124, 20, 531, 953, 591, 886, 320,
98+
696, 71, 859, 578, 175, 587, 707, 663, 283, 179, 795, 989, 702, 940, 371,
99+
692, 689, 555, 903, 410, 651, 75, 429, 818, 362, 894, 515, 31, 545, 666,
100+
706, 952, 864, 269, 254, 349, 711, 802, 716, 784, 1007, 925, 801, 445,
101+
148, 260, 658, 385, 287, 262, 204, 126, 586, 1004, 236, 165, 854, 411,
102+
932, 560, 19, 215, 1002, 775, 653, 928, 901, 964, 884, 798, 839, 786,
103+
433, 610, 116, 855, 180, 479, 910, 1014, 599, 915, 905, 306, 516, 731,
104+
626, 978, 825, 344, 605, 654, 209
105+
};
106+
static_assert(std::size(GF1024_EXP) == 1023, "GF1024_EXP length should be 1023");
107+
108+
const int16_t GF1024_LOG[] = {
109+
-1, 0, 99, 363, 198, 726, 462, 132, 297, 495, 825, 528, 561, 693, 231,
110+
66, 396, 429, 594, 990, 924, 264, 627, 33, 660, 759, 792, 858, 330, 891,
111+
165, 957, 104, 259, 518, 208, 280, 776, 416, 13, 426, 333, 618, 339, 641,
112+
52, 388, 140, 666, 852, 529, 560, 678, 213, 26, 832, 681, 309, 70, 194,
113+
97, 35, 682, 341, 203, 777, 358, 312, 617, 125, 307, 931, 379, 765, 875,
114+
951, 515, 628, 112, 659, 525, 196, 432, 134, 717, 781, 438, 440, 740,
115+
780, 151, 408, 487, 169, 239, 293, 467, 21, 672, 622, 557, 571, 881, 433,
116+
704, 376, 779, 22, 643, 460, 398, 116, 172, 503, 751, 389, 1004, 18, 576,
117+
415, 789, 6, 192, 696, 923, 702, 981, 892, 302, 816, 876, 880, 457, 537,
118+
411, 539, 716, 624, 224, 295, 406, 531, 7, 233, 478, 586, 864, 268, 974,
119+
338, 27, 392, 614, 839, 727, 879, 211, 250, 758, 507, 830, 129, 369, 384,
120+
36, 985, 12, 555, 232, 796, 221, 321, 920, 263, 42, 934, 778, 479, 761,
121+
939, 1006, 344, 381, 823, 44, 535, 866, 739, 752, 385, 119, 91, 566, 80,
122+
120, 117, 771, 675, 721, 514, 656, 271, 670, 602, 980, 850, 532, 488,
123+
803, 1022, 475, 801, 878, 57, 121, 991, 742, 888, 559, 105, 497, 291,
124+
215, 795, 236, 167, 692, 520, 272, 661, 229, 391, 814, 340, 184, 798,
125+
984, 773, 650, 473, 345, 558, 548, 326, 202, 145, 465, 810, 471, 158,
126+
813, 908, 412, 441, 964, 750, 401, 50, 915, 437, 975, 126, 979, 491, 556,
127+
577, 636, 685, 510, 963, 638, 367, 815, 310, 723, 349, 323, 857, 394,
128+
606, 505, 713, 630, 938, 106, 826, 332, 978, 599, 834, 521, 530, 248,
129+
883, 32, 153, 90, 754, 592, 304, 635, 775, 804, 1, 150, 836, 1013, 828,
130+
324, 565, 508, 113, 154, 708, 921, 703, 689, 138, 547, 911, 929, 82, 228,
131+
443, 468, 480, 483, 922, 135, 877, 61, 578, 111, 860, 654, 15, 331, 851,
132+
895, 484, 320, 218, 420, 190, 1019, 143, 362, 634, 141, 965, 10, 838,
133+
632, 861, 34, 722, 580, 808, 869, 554, 598, 65, 954, 787, 337, 187, 281,
134+
146, 563, 183, 668, 944, 171, 837, 23, 867, 541, 916, 741, 625, 123, 736,
135+
186, 357, 665, 977, 179, 156, 219, 220, 216, 67, 870, 902, 774, 98, 820,
136+
574, 613, 900, 755, 596, 370, 390, 769, 314, 701, 894, 56, 841, 949, 987,
137+
631, 658, 587, 204, 797, 790, 522, 745, 9, 502, 763, 86, 719, 288, 706,
138+
887, 728, 952, 311, 336, 446, 1002, 348, 96, 58, 199, 11, 901, 230, 833,
139+
188, 352, 351, 973, 3, 906, 335, 301, 266, 244, 791, 564, 619, 909, 371,
140+
444, 760, 657, 328, 647, 490, 425, 913, 511, 439, 540, 283, 40, 897, 849,
141+
60, 570, 872, 257, 749, 912, 572, 1007, 170, 407, 898, 492, 79, 747, 732,
142+
206, 454, 918, 375, 482, 399, 92, 748, 325, 163, 274, 405, 744, 260, 346,
143+
707, 626, 595, 118, 842, 136, 279, 684, 584, 101, 500, 422, 149, 956,
144+
1014, 493, 536, 705, 51, 914, 225, 409, 55, 822, 590, 448, 655, 205, 676,
145+
925, 735, 431, 784, 54, 609, 604, 39, 812, 737, 729, 466, 14, 533, 958,
146+
481, 770, 499, 855, 238, 182, 464, 569, 72, 947, 442, 642, 24, 87, 989,
147+
688, 88, 47, 762, 623, 709, 455, 817, 526, 637, 258, 84, 845, 738, 768,
148+
698, 423, 933, 664, 620, 607, 629, 212, 347, 249, 982, 935, 131, 89, 252,
149+
927, 189, 788, 853, 237, 691, 646, 403, 1010, 734, 253, 874, 807, 903,
150+
1020, 100, 802, 71, 799, 1003, 633, 355, 276, 300, 649, 64, 306, 161,
151+
608, 496, 743, 180, 485, 819, 383, 1016, 226, 308, 393, 648, 107, 19, 37,
152+
585, 2, 175, 645, 247, 527, 5, 419, 181, 317, 327, 519, 542, 289, 567,
153+
430, 579, 950, 582, 994, 1021, 583, 234, 240, 976, 41, 160, 109, 677,
154+
937, 210, 95, 959, 242, 753, 461, 114, 733, 368, 573, 458, 782, 605, 680,
155+
544, 299, 73, 652, 905, 477, 690, 93, 824, 882, 277, 946, 361, 17, 945,
156+
523, 472, 334, 930, 597, 603, 793, 404, 290, 942, 316, 731, 270, 960,
157+
936, 133, 122, 821, 966, 679, 662, 907, 282, 968, 767, 653, 20, 697, 222,
158+
164, 835, 30, 285, 886, 456, 436, 640, 286, 1015, 380, 840, 245, 724,
159+
137, 593, 173, 130, 715, 85, 885, 551, 246, 449, 103, 366, 372, 714, 313,
160+
865, 241, 699, 674, 374, 68, 421, 562, 292, 59, 809, 342, 651, 459, 227,
161+
46, 711, 764, 868, 53, 413, 278, 800, 255, 993, 318, 854, 319, 695, 315,
162+
469, 166, 489, 969, 730, 1001, 757, 873, 686, 197, 303, 919, 155, 673,
163+
940, 712, 25, 999, 63, 863, 972, 967, 785, 152, 296, 512, 402, 377, 45,
164+
899, 829, 354, 77, 69, 856, 417, 811, 953, 124, 418, 75, 794, 162, 414,
165+
1018, 568, 254, 265, 772, 588, 16, 896, 157, 889, 298, 621, 110, 844,
166+
1000, 108, 545, 601, 78, 862, 447, 185, 195, 818, 450, 387, 49, 805, 102,
167+
986, 1005, 827, 329, 28, 932, 410, 287, 435, 451, 962, 517, 48, 174, 43,
168+
893, 884, 261, 251, 516, 395, 910, 611, 29, 501, 223, 476, 364, 144, 871,
169+
998, 687, 928, 115, 453, 513, 176, 94, 168, 667, 955, 353, 434, 382, 400,
170+
139, 365, 996, 343, 948, 890, 1012, 663, 610, 718, 538, 1008, 639, 470,
171+
848, 543, 1011, 859, 671, 756, 83, 427, 159, 746, 669, 589, 971, 524,
172+
356, 995, 904, 256, 201, 988, 62, 397, 81, 720, 917, 209, 549, 943, 486,
173+
76, 148, 207, 509, 644, 386, 700, 534, 177, 550, 961, 926, 546, 428, 284,
174+
127, 294, 8, 269, 359, 506, 445, 997, 806, 591, 725, 178, 262, 846, 373,
175+
831, 504, 305, 843, 553, 378, 1017, 783, 474, 683, 581, 200, 498, 694,
176+
191, 217, 847, 941, 424, 235, 38, 74, 616, 786, 147, 4, 273, 214, 142,
177+
575, 992, 463, 983, 243, 360, 970, 350, 267, 615, 766, 494, 31, 1009,
178+
452, 710, 552, 128, 612, 600, 275, 322, 193
179+
};
180+
static_assert(std::size(GF1024_LOG) == 1024, "GF1024_EXP length should be 1024");
181+
33182
/* Determine the final constant to use for the specified encoding. */
34183
uint32_t EncodingConstant(Encoding encoding) {
35184
assert(encoding == Encoding::BECH32 || encoding == Encoding::BECH32M);
@@ -127,12 +276,73 @@ uint32_t PolyMod(const data& v)
127276
return c;
128277
}
129278

279+
uint32_t Syndrome(const uint32_t residue) {
280+
uint32_t low = residue & 0x1f;
281+
return low ^ (low << 10) ^ (low << 20) ^
282+
((residue >> 5) & 1 ? 0x31edd3c4 : 0) ^
283+
((residue >> 6) & 1 ? 0x335f86a8 : 0) ^
284+
((residue >> 7) & 1 ? 0x363b8870 : 0) ^
285+
((residue >> 8) & 1 ? 0x3e6390c9 : 0) ^
286+
((residue >> 9) & 1 ? 0x2ec72192 : 0) ^
287+
((residue >> 10) & 1 ? 0x1046f79d : 0) ^
288+
((residue >> 11) & 1 ? 0x208d4e33 : 0) ^
289+
((residue >> 12) & 1 ? 0x130ebd6f : 0) ^
290+
((residue >> 13) & 1 ? 0x2499fade : 0) ^
291+
((residue >> 14) & 1 ? 0x1b27d4b5 : 0) ^
292+
((residue >> 15) & 1 ? 0x04be1eb4 : 0) ^
293+
((residue >> 16) & 1 ? 0x0968b861 : 0) ^
294+
((residue >> 17) & 1 ? 0x1055f0c2 : 0) ^
295+
((residue >> 18) & 1 ? 0x20ab4584 : 0) ^
296+
((residue >> 19) & 1 ? 0x1342af08 : 0) ^
297+
((residue >> 20) & 1 ? 0x24f1f318 : 0) ^
298+
((residue >> 21) & 1 ? 0x1be34739 : 0) ^
299+
((residue >> 22) & 1 ? 0x35562f7b : 0) ^
300+
((residue >> 23) & 1 ? 0x3a3c5bff : 0) ^
301+
((residue >> 24) & 1 ? 0x266c96f7 : 0) ^
302+
((residue >> 25) & 1 ? 0x25c78b65 : 0) ^
303+
((residue >> 26) & 1 ? 0x1b1f13ea : 0) ^
304+
((residue >> 27) & 1 ? 0x34baa2f4 : 0) ^
305+
((residue >> 28) & 1 ? 0x3b61c0e1 : 0) ^
306+
((residue >> 29) & 1 ? 0x265325c2 : 0);
307+
}
308+
130309
/** Convert to lower case. */
131310
inline unsigned char LowerCase(unsigned char c)
132311
{
133312
return (c >= 'A' && c <= 'Z') ? (c - 'A') + 'a' : c;
134313
}
135314

315+
void push_range(int from, int to, std::vector<int>& vec)
316+
{
317+
for (int i = from; i < to; i++) {
318+
vec.push_back(i);
319+
}
320+
}
321+
322+
/** Return index of first invalid character in a Bech32 string. */
323+
bool CheckCharacters(const std::string& str, std::vector<int>& errors) {
324+
bool lower = false, upper = false;
325+
for (size_t i = 0; i < str.size(); ++i) {
326+
unsigned char c = str[i];
327+
if (c >= 'a' && c <= 'z') {
328+
if (upper) {
329+
errors.push_back(i);
330+
} else {
331+
lower = true;
332+
}
333+
} else if (c >= 'A' && c <= 'Z') {
334+
if (lower) {
335+
errors.push_back(i);
336+
} else {
337+
upper = true;
338+
}
339+
} else if (c < 33 || c > 126) {
340+
errors.push_back(i);
341+
}
342+
}
343+
return errors.empty();
344+
}
345+
136346
/** Expand a HRP for use in checksum computation. */
137347
data ExpandHRP(const std::string& hrp)
138348
{
@@ -196,14 +406,8 @@ std::string Encode(Encoding encoding, const std::string& hrp, const data& values
196406

197407
/** Decode a Bech32 or Bech32m string. */
198408
DecodeResult Decode(const std::string& str) {
199-
bool lower = false, upper = false;
200-
for (size_t i = 0; i < str.size(); ++i) {
201-
unsigned char c = str[i];
202-
if (c >= 'a' && c <= 'z') lower = true;
203-
else if (c >= 'A' && c <= 'Z') upper = true;
204-
else if (c < 33 || c > 126) return {};
205-
}
206-
if (lower && upper) return {};
409+
std::vector<int> errors;
410+
if (!CheckCharacters(str, errors)) return {};
207411
size_t pos = str.rfind('1');
208412
if (str.size() > 90 || pos == str.npos || pos == 0 || pos + 7 > str.size()) {
209413
return {};
@@ -227,4 +431,103 @@ DecodeResult Decode(const std::string& str) {
227431
return {result, std::move(hrp), data(values.begin(), values.end() - 6)};
228432
}
229433

434+
/** Find index of an incorrect character in a Bech32 string. */
435+
std::string LocateErrors(const std::string& str, std::vector<int>& error_locations) {
436+
if (str.size() > 90) {
437+
push_range(90, str.size(), error_locations);
438+
return "Bech32 string too long";
439+
}
440+
if (!CheckCharacters(str, error_locations)){
441+
return "Invalid character or mixed case";
442+
}
443+
size_t pos = str.rfind('1');
444+
if (pos == str.npos) {
445+
return "Missing separator";
446+
}
447+
if (pos == 0 || pos + 7 > str.size()) {
448+
error_locations.push_back(pos);
449+
return "Invalid separator position";
450+
}
451+
std::string hrp;
452+
for (size_t i = 0; i < pos; ++i) {
453+
hrp += LowerCase(str[i]);
454+
}
455+
456+
size_t length = str.size() - 1 - pos; // length of data part
457+
data values(length);
458+
for (size_t i = pos + 1; i < str.size(); ++i) {
459+
unsigned char c = str[i];
460+
int8_t rev = CHARSET_REV[c];
461+
if (rev == -1) {
462+
error_locations.push_back(i);
463+
return "Invalid Base 32 character";
464+
}
465+
values[i - pos - 1] = rev;
466+
}
467+
468+
// We attempt error detection with both bech32 and bech32m, and choose the one with the fewest errors
469+
// We can't simply use the segwit version, because that may be one of the errors
470+
for (Encoding encoding : {Encoding::BECH32, Encoding::BECH32M}) {
471+
std::vector<int> possible_errors;
472+
uint32_t residue = PolyMod(Cat(ExpandHRP(hrp), values)) ^ EncodingConstant(encoding);
473+
if (residue != 0) {
474+
uint32_t syn = Syndrome(residue);
475+
int s0 = syn & 0x3FF;
476+
int s1 = (syn >> 10) & 0x3FF;
477+
int s2 = syn >> 20;
478+
int l_s0 = GF1024_LOG[s0];
479+
int l_s1 = GF1024_LOG[s1];
480+
int l_s2 = GF1024_LOG[s2];
481+
482+
if (l_s0 != -1 && l_s1 != -1 && l_s2 != -1 && (2 * l_s1 - l_s2 - l_s0 + 2046) % 1023 == 0) {
483+
size_t p1 = (l_s1 - l_s0 + 1023) % 1023;
484+
int l_e1 = l_s0 + (1023 - 997) * p1;
485+
if (p1 < length && !(l_e1 % 33)) {
486+
possible_errors.push_back(str.size() - p1 - 1);
487+
}
488+
} else {
489+
for (size_t p1 = 0; p1 < length; ++p1) {
490+
int s2_s1p1 = s2 ^ (s1 == 0 ? 0 : GF1024_EXP[(l_s1 + p1) % 1023]);
491+
if (s2_s1p1 == 0) continue;
492+
493+
int s1_s0p1 = s1 ^ (s0 == 0 ? 0 : GF1024_EXP[(l_s0 + p1) % 1023]);
494+
if (s1_s0p1 == 0) continue;
495+
496+
int l_s1_s0p1 = GF1024_LOG[s1_s0p1];
497+
size_t p2 = (GF1024_LOG[s2_s1p1] - l_s1_s0p1 + 1023) % 1023;
498+
if (p2 >= length || p1 == p2) continue;
499+
500+
int s1_s0p2 = s1 ^ (s0 == 0 ? 0 : GF1024_EXP[(l_s0 + p2) % 1023]);
501+
if (s1_s0p2 == 0) continue;
502+
503+
int inv_p1_p2 = 1023 - GF1024_LOG[GF1024_EXP[p1] ^ GF1024_EXP[p2]];
504+
int l_e2 = l_s1_s0p1 + inv_p1_p2 + (1023 - 997) * p2;
505+
if (l_e2 % 33) continue;
506+
507+
int l_e1 = GF1024_LOG[s1_s0p2] + inv_p1_p2 + (1023 - 997) * p1;
508+
if (l_e1 % 33) continue;
509+
510+
if (p1 > p2) {
511+
possible_errors.push_back(str.size() - p1 - 1);
512+
possible_errors.push_back(str.size() - p2 - 1);
513+
} else {
514+
possible_errors.push_back(str.size() - p2 - 1);
515+
possible_errors.push_back(str.size() - p1 - 1);
516+
}
517+
break;
518+
}
519+
}
520+
} else {
521+
// No errors
522+
error_locations.clear();
523+
return "";
524+
}
525+
526+
if (error_locations.empty() || (!possible_errors.empty() && possible_errors.size() < error_locations.size())) {
527+
error_locations = std::move(possible_errors);
528+
}
529+
}
530+
return "Invalid checksum";
531+
}
532+
230533
} // namespace bech32

‎src/bech32.h

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -44,6 +44,9 @@ struct DecodeResult
4444
/** Decode a Bech32 or Bech32m string. */
4545
DecodeResult Decode(const std::string& str);
4646

47+
/** Return the positions of errors in a Bech32 string. */
48+
std::string LocateErrors(const std::string& str, std::vector<int>& error_locations);
49+
4750
} // namespace bech32
4851

4952
#endif // BITCOIN_BECH32_H

0 commit comments

Comments
 (0)