1 /* Makes safe primes of a DR nature */ 2 #include <tommath.h> 3 4 int sizes[] = { 1+256/DIGIT_BIT, 1+512/DIGIT_BIT, 1+768/DIGIT_BIT, 1+1024/DIGIT_BIT, 1+2048/DIGIT_BIT, 1+4096/DIGIT_BIT }; 5 int main(void) 6 { 7 int res, x, y; 8 char buf[4096]; 9 FILE *out; 10 mp_int a, b; 11 12 mp_init(&a); 13 mp_init(&b); 14 15 out = fopen("drprimes.txt", "w"); 16 for (x = 0; x < (int)(sizeof(sizes)/sizeof(sizes[0])); x++) { 17 top: 18 printf("Seeking a %d-bit safe prime\n", sizes[x] * DIGIT_BIT); 19 mp_grow(&a, sizes[x]); 20 mp_zero(&a); 21 for (y = 1; y < sizes[x]; y++) { 22 a.dp[y] = MP_MASK; 23 } 24 25 /* make a DR modulus */ 26 a.dp[0] = -1; 27 a.used = sizes[x]; 28 29 /* now loop */ 30 res = 0; 31 for (;;) { 32 a.dp[0] += 4; 33 if (a.dp[0] >= MP_MASK) break; 34 mp_prime_is_prime(&a, 1, &res); 35 if (res == 0) continue; 36 printf("."); fflush(stdout); 37 mp_sub_d(&a, 1, &b); 38 mp_div_2(&b, &b); 39 mp_prime_is_prime(&b, 3, &res); 40 if (res == 0) continue; 41 mp_prime_is_prime(&a, 3, &res); 42 if (res == 1) break; 43 } 44 45 if (res != 1) { 46 printf("Error not DR modulus\n"); sizes[x] += 1; goto top; 47 } else { 48 mp_toradix(&a, buf, 10); 49 printf("\n\np == %s\n\n", buf); 50 fprintf(out, "%d-bit prime:\np == %s\n\n", mp_count_bits(&a), buf); fflush(out); 51 } 52 } 53 fclose(out); 54 55 mp_clear(&a); 56 mp_clear(&b); 57 58 return 0; 59 } 60 61 62 /* $Source: /cvs/libtom/libtommath/etc/drprime.c,v $ */ 63 /* $Revision: 1.2 $ */ 64 /* $Date: 2005/05/05 14:38:47 $ */ 65
