kc3-lang/libtommath/etc/drprime.c

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• Hash : f8e9bd27
  Author :
  Date : 2019-10-20T15:38:32
  

  Merge pull request #387 from fperrad/20191019_lint some linting (cherry picked from commit 8095b3b61240628f052153d6c37539955632564e)

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• etc/drprime.c

• /* Makes safe primes of a DR nature */
  #include <tommath.h>
  
  static int sizes[] = { 1+256/MP_DIGIT_BIT, 1+512/MP_DIGIT_BIT, 1+768/MP_DIGIT_BIT, 1+1024/MP_DIGIT_BIT, 1+2048/MP_DIGIT_BIT, 1+4096/MP_DIGIT_BIT };
  
  int main(void)
  {
     mp_bool res;
     int x, y;
     char buf[4096];
     FILE *out;
     mp_int a, b;
  
     mp_init(&a);
     mp_init(&b);
  
     out = fopen("drprimes.txt", "w");
     if (out != NULL) {
        for (x = 0; x < (int)(sizeof(sizes)/sizeof(sizes[0])); x++) {
  top:
           printf("Seeking a %d-bit safe prime\n", sizes[x] * MP_DIGIT_BIT);
           mp_grow(&a, sizes[x]);
           mp_zero(&a);
           for (y = 1; y < sizes[x]; y++) {
              a.dp[y] = MP_MASK;
           }
  
           /* make a DR modulus */
           a.dp[0] = -1;
           a.used = sizes[x];
  
           /* now loop */
           res = MP_NO;
           for (;;) {
              a.dp[0] += 4uL;
              if (a.dp[0] >= MP_MASK) break;
              mp_prime_is_prime(&a, 1, &res);
              if (res == MP_NO) continue;
              printf(".");
              fflush(stdout);
              mp_sub_d(&a, 1uL, &b);
              mp_div_2(&b, &b);
              mp_prime_is_prime(&b, 3, &res);
              if (res == MP_NO) continue;
              mp_prime_is_prime(&a, 3, &res);
              if (res == MP_YES) break;
           }
  
           if (res != MP_YES) {
              printf("Error not DR modulus\n");
              sizes[x] += 1;
              goto top;
           } else {
              mp_to_decimal(&a, buf, sizeof(buf));
              printf("\n\np == %s\n\n", buf);
              fprintf(out, "%d-bit prime:\np == %s\n\n", mp_count_bits(&a), buf);
              fflush(out);
           }
        }
        fclose(out);
     }
  
     mp_clear(&a);
     mp_clear(&b);
  
     return 0;
  }
  

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