#include "../includes/rsa.h"

int64_t euler(int64_t r0, int64_t r1) {
	int64_t s0 = 1;
	int64_t s1 = 0;
	int64_t t0 = 0;
	int64_t t1 = 1;
	int64_t q0 = 0;

	while (r1 != 0) {
		q0 = r0 / r1;
		int64_t tmp = r0 % r1;
		r0 = r1;
		r1 = tmp;
		tmp = s0 - q0 * s1;
		s0 = s1;
		s1 = tmp;
		tmp = t0 - q0 * t1;
		t0 = t1;
		t1 = tmp;
	}
	return s0;
}

rsa_t rsa_generate_keys(void) {
	int64_t p = (uint64_t)generate_prime();
	int64_t q = (uint64_t)generate_prime();
	int64_t ln = (p - 1) * (q - 1);
	int64_t e = 11317;

	while (ln % e == 0 || p == q) {
		p = generate_prime();
		q = generate_prime();
		ln = (p - 1) * (q - 1);
	}

	if (q > p) {
		uint64_t tmp = p;
		p = q;
		q = tmp;
	}

	int64_t n = p * q;
	int64_t d = euler(e, ln) + ln;
	if (d > n) {
		d -= ln;
	}
	rsa_t rsa;
	rsa.d = d;
	rsa.n = n;
	return rsa;
}