github.com/ethereum/go-ethereum@v1.16.1/crypto/secp256k1/libsecp256k1/src/precompute_ecmult.c (about)

     1  /*****************************************************************************************************
     2   * Copyright (c) 2013, 2014, 2017, 2021 Pieter Wuille, Andrew Poelstra, Jonas Nick, Russell O'Connor *
     3   * Distributed under the MIT software license, see the accompanying                                  *
     4   * file COPYING or https://www.opensource.org/licenses/mit-license.php.                              *
     5   *****************************************************************************************************/
     6  
     7  #include <inttypes.h>
     8  #include <stdio.h>
     9  #include <stdlib.h>
    10  
    11  #include "../include/secp256k1.h"
    12  
    13  #include "assumptions.h"
    14  #include "util.h"
    15  
    16  #include "field_impl.h"
    17  #include "group_impl.h"
    18  #include "int128_impl.h"
    19  #include "ecmult.h"
    20  #include "ecmult_compute_table_impl.h"
    21  
    22  static void print_table(FILE *fp, const char *name, int window_g, const secp256k1_ge_storage* table) {
    23      int j;
    24      int i;
    25  
    26      fprintf(fp, "const secp256k1_ge_storage %s[ECMULT_TABLE_SIZE(WINDOW_G)] = {\n", name);
    27      fprintf(fp, " S(%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32
    28                    ",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32")\n",
    29                  SECP256K1_GE_STORAGE_CONST_GET(table[0]));
    30  
    31      j = 1;
    32      for(i = 3; i <= window_g; ++i) {
    33          fprintf(fp, "#if WINDOW_G > %d\n", i-1);
    34          for(;j < ECMULT_TABLE_SIZE(i); ++j) {
    35              fprintf(fp, ",S(%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32
    36                            ",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32",%"PRIx32")\n",
    37                          SECP256K1_GE_STORAGE_CONST_GET(table[j]));
    38          }
    39          fprintf(fp, "#endif\n");
    40      }
    41      fprintf(fp, "};\n");
    42  }
    43  
    44  static void print_two_tables(FILE *fp, int window_g) {
    45      secp256k1_ge_storage* table = malloc(ECMULT_TABLE_SIZE(window_g) * sizeof(secp256k1_ge_storage));
    46      secp256k1_ge_storage* table_128 = malloc(ECMULT_TABLE_SIZE(window_g) * sizeof(secp256k1_ge_storage));
    47  
    48      secp256k1_ecmult_compute_two_tables(table, table_128, window_g, &secp256k1_ge_const_g);
    49  
    50      print_table(fp, "secp256k1_pre_g", window_g, table);
    51      print_table(fp, "secp256k1_pre_g_128", window_g, table_128);
    52  
    53      free(table);
    54      free(table_128);
    55  }
    56  
    57  int main(void) {
    58      /* Always compute all tables for window sizes up to 15. */
    59      int window_g = (ECMULT_WINDOW_SIZE < 15) ? 15 : ECMULT_WINDOW_SIZE;
    60      const char outfile[] = "src/precomputed_ecmult.c";
    61      FILE* fp;
    62  
    63      fp = fopen(outfile, "w");
    64      if (fp == NULL) {
    65          fprintf(stderr, "Could not open %s for writing!\n", outfile);
    66          return EXIT_FAILURE;
    67      }
    68  
    69      fprintf(fp, "/* This file was automatically generated by precompute_ecmult. */\n");
    70      fprintf(fp, "/* This file contains an array secp256k1_pre_g with odd multiples of the base point G and\n");
    71      fprintf(fp, " * an array secp256k1_pre_g_128 with odd multiples of 2^128*G for accelerating the computation of a*P + b*G.\n");
    72      fprintf(fp, " */\n");
    73      fprintf(fp, "#include \"group.h\"\n");
    74      fprintf(fp, "#include \"ecmult.h\"\n");
    75      fprintf(fp, "#include \"precomputed_ecmult.h\"\n");
    76      fprintf(fp, "#define S(a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p) SECP256K1_GE_STORAGE_CONST(0x##a##u,0x##b##u,0x##c##u,0x##d##u,0x##e##u,0x##f##u,0x##g##u,0x##h##u,0x##i##u,0x##j##u,0x##k##u,0x##l##u,0x##m##u,0x##n##u,0x##o##u,0x##p##u)\n");
    77      fprintf(fp, "#if ECMULT_WINDOW_SIZE > %d\n", window_g);
    78      fprintf(fp, "   #error configuration mismatch, invalid ECMULT_WINDOW_SIZE. Try deleting precomputed_ecmult.c before the build.\n");
    79      fprintf(fp, "#endif\n");
    80      fprintf(fp, "#ifdef EXHAUSTIVE_TEST_ORDER\n");
    81      fprintf(fp, "#    error Cannot compile precomputed_ecmult.c in exhaustive test mode\n");
    82      fprintf(fp, "#endif /* EXHAUSTIVE_TEST_ORDER */\n");
    83      fprintf(fp, "#define WINDOW_G ECMULT_WINDOW_SIZE\n");
    84  
    85      print_two_tables(fp, window_g);
    86  
    87      fprintf(fp, "#undef S\n");
    88      fclose(fp);
    89  
    90      return EXIT_SUCCESS;
    91  }