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65 lines
1.6 KiB
C
65 lines
1.6 KiB
C
/* Makes safe primes of a DR nature */
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#include <tommath.h>
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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 };
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int main(void)
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{
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int res, x, y;
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char buf[4096];
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FILE *out;
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mp_int a, b;
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mp_init(&a);
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mp_init(&b);
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out = fopen("drprimes.txt", "w");
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for (x = 0; x < (int)(sizeof(sizes)/sizeof(sizes[0])); x++) {
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top:
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printf("Seeking a %d-bit safe prime\n", sizes[x] * DIGIT_BIT);
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mp_grow(&a, sizes[x]);
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mp_zero(&a);
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for (y = 1; y < sizes[x]; y++) {
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a.dp[y] = MP_MASK;
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}
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/* make a DR modulus */
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a.dp[0] = -1;
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a.used = sizes[x];
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/* now loop */
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res = 0;
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for (;;) {
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a.dp[0] += 4;
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if (a.dp[0] >= MP_MASK) break;
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mp_prime_is_prime(&a, 1, &res);
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if (res == 0) continue;
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printf("."); fflush(stdout);
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mp_sub_d(&a, 1, &b);
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mp_div_2(&b, &b);
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mp_prime_is_prime(&b, 3, &res);
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if (res == 0) continue;
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mp_prime_is_prime(&a, 3, &res);
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if (res == 1) break;
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}
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if (res != 1) {
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printf("Error not DR modulus\n"); sizes[x] += 1; goto top;
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} else {
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mp_toradix(&a, buf, 10);
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printf("\n\np == %s\n\n", buf);
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fprintf(out, "%d-bit prime:\np == %s\n\n", mp_count_bits(&a), buf); fflush(out);
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}
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}
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fclose(out);
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mp_clear(&a);
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mp_clear(&b);
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return 0;
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}
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/* $Source: /cvs/libtom/libtommath/etc/drprime.c,v $ */
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/* $Revision: 1.2 $ */
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/* $Date: 2005/05/05 14:38:47 $ */
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