116 lines
2.9 KiB
C
116 lines
2.9 KiB
C
#include <inttypes.h>
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#include <stdbool.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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uint64_t *dec_to_bin(uint64_t d, uint64_t *length) {
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uint64_t *binary_form = calloc(100, sizeof(uint64_t));
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int index = 0;
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while (d != 0) {
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binary_form[index] = d % 2;
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d /= 2;
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index++;
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}
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*length = index;
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for (int i = index; i >= 0; i--) {
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printf("%ju", binary_form[i]);
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}
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printf(" index: %d\n", index);
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return binary_form;
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}
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uint64_t quick_pow(uint64_t *d_binary, uint64_t a, uint64_t n, uint64_t length) {
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uint64_t *powed = calloc(100, sizeof(uint64_t));
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powed[0] = a;
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for (int i = 1; i <= length; i++) {
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// powed[i] = (powed[i - 1] * powed[i - 1]) % n;
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powed[i] = (uint64_t)(((unsigned __int128)powed[i - 1] * powed[i - 1]) % n);
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// printf("powed: %ju, index: %d; ", powed[i], (i));
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}
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// check where in the binary are ones
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uint64_t multiplied = 1;
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for (int i = 0; i < length; i++) {
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if (d_binary[i] == 1) {
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// multiplied = (multiplied * powed[i]) % n;
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multiplied = (uint64_t)(((unsigned __int128)multiplied * powed[i]) % n);
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}
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}
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// printf("\nbm quick math: %ju; %ju ", multiplied, n);
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free(powed);
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return multiplied;
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}
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bool prime_test(uint64_t n, int a) {
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printf("\n\nprime test: %ju\n", n);
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// Miller Rabin prime test
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// choose a base: a, which should be a prime so that (n, a) = 1
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// then do 2 rounds of tests provided the first one did not fail
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// 1: a^d =k 1 mod n
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// 2: a^(d * 2^r) =k n-1 mod n
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// d = n-1 / 2^S (where S means how many time did we divide the number till we reached the first odd number)
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// S: see above
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// r = {0,... S-1}
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uint64_t d = n - 1;
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uint64_t S = 0;
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while (d % 2 == 0) {
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d = d / 2;
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S++;
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printf("%ju ", d);
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}
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printf("S: %ju", S);
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printf("\n");
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uint64_t r = S - 1; // this stores the number of elements from 0 to S-1
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// round 1
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// 1: a^d =k 1 mod n
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uint64_t length;
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uint64_t *d_binary = dec_to_bin(d, &length);
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uint64_t first_qp_res = 0;
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if ((first_qp_res = quick_pow(d_binary, a, n, length)) == 1) {
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free(d_binary);
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printf("true\n");
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return true;
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}
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// round 2
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// 2: a^(d * 2^r) =k n-1 mod n
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for (int i = 0; i <= r; i++) {
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if (first_qp_res == n - 1) {
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free(d_binary);
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printf("true\n");
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return true;
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} else {
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// first_qp_res = (first_qp_res * first_qp_res) % n;
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first_qp_res = (uint64_t)(((unsigned __int128)first_qp_res * first_qp_res) % n);
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}
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}
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printf("\nfalse\n\n");
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free(d_binary);
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return false;
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}
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int main() {
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prime_test(111, 5);
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prime_test(29, 2);
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prime_test(27, 2);
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prime_test(17, 2);
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prime_test(661, 2);
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prime_test(18446744073709551557UL, 2);
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prime_test(18446744073709551533UL, 3);
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return 0;
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}
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