/* $NetBSD: drprime.c,v 1.1.1.2 2014/04/24 12:45:39 pettai Exp $ */ /* Makes safe primes of a DR nature */ #include 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 }; int main(void) { int res, x, y; char buf[4096]; FILE *out; mp_int a, b; mp_init(&a); mp_init(&b); out = fopen("drprimes.txt", "w"); for (x = 0; x < (int)(sizeof(sizes)/sizeof(sizes[0])); x++) { top: printf("Seeking a %d-bit safe prime\n", sizes[x] * 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 = 0; for (;;) { a.dp[0] += 4; if (a.dp[0] >= MP_MASK) break; mp_prime_is_prime(&a, 1, &res); if (res == 0) continue; printf("."); fflush(stdout); mp_sub_d(&a, 1, &b); mp_div_2(&b, &b); mp_prime_is_prime(&b, 3, &res); if (res == 0) continue; mp_prime_is_prime(&a, 3, &res); if (res == 1) break; } if (res != 1) { printf("Error not DR modulus\n"); sizes[x] += 1; goto top; } else { mp_toradix(&a, buf, 10); 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; } /* Source: /cvs/libtom/libtommath/etc/drprime.c,v */ /* Revision: 1.2 */ /* Date: 2005/05/05 14:38:47 */