int main()
{
int XA, XB, YA, YB, ka, kb;
printf("Enter the global prime q : ");
scanf("%d", &q);
a = primitiveRoot(q);
srand(time(NULL));
//the private keys
XA = (rand() % (q - 1)) + 1;
XB = (rand() % (q - 1)) + 1;
//the public keys
YA = abmodn(a, XA, q);
YB = abmodn(a, XB, q);
//calculation of keys
ka = abmodn(YB, XA, q);
kb = abmodn(YA, XB, q);
printf("XA = %d\nXB = %d\nYA = %d\nYB = %d\nka = %d\nkb = %d\n", XA, XB, YA, YB, ka, kb);
if(ka == kb) {
printf("Diffie hellman executed correctly :\nka = kb = %d\n", ka, kb);
} else {
printf("There was some problem. Quitting quitely\n");
return -1;
}
return 0;
}
//returns x: x^k = a mod mod, mod is prime
int discreteRoot(int a, int k, int mod) {
if (a == 0)
return 0;
int g = primitiveRoot(mod);
int y = discreteLogariphm(power(g, k, mod), a, mod);
return power(g, y, mod);
}
