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