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CryptoSystem.cpp
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CryptoSystem.cpp
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//
// Created by mmbil on 10/05/2023.
//
#include "CryptoSystem.h"
CryptoSystem::CryptoSystem() = default;
void CryptoSystem::generate_rsa_key(mp::cpp_int p, mp::cpp_int q) {
n = p * q;
z = (p - 1) * (q - 1);
e = 0;
while (true) {
e = get_rand_num();
if ( (e < 1) || (e == p) || (e == q) || (e >= n) ) {
continue;
}
mp::cpp_int gcd_of_e_z = euclidean_algo(e, z);
if (gcd_of_e_z == 1) {
break;
}
}
d = extended_euclidean_algo(z, e);
}
void CryptoSystem::generate_fixed_rsa_key(mp::cpp_int p, mp::cpp_int q) {
n = p * q;
z = (p - 1) * (q - 1);
e = mp::cpp_int(159826223);
d = extended_euclidean_algo(z, e);
}
mp::cpp_int CryptoSystem::get_e() {return e;}
mp::cpp_int CryptoSystem::get_n() {return n;}
mp::cpp_int CryptoSystem::get_d() {return d;}
mp::cpp_int CryptoSystem::encrypt_rsa(mp::cpp_int m, mp::cpp_int e, mp::cpp_int n) {
return mp::powm(m, e, n);
}
mp::cpp_int CryptoSystem::decrypt_rsa(mp::cpp_int m, mp::cpp_int d, mp::cpp_int n) {
return mp::powm(m, d, n);
}
mp::cpp_int CryptoSystem::encrypt_rsa_cbc(mp::cpp_int m, mp::cpp_int e, mp::cpp_int n, mp::cpp_int rand) {
return encrypt_rsa((m ^ rand), e, n);
}
mp::cpp_int CryptoSystem::decrypt_rsa_cbc(mp::cpp_int m, mp::cpp_int d, mp::cpp_int n, mp::cpp_int rand) {
return decrypt_rsa(m, d, n) ^ rand;
}
mp::cpp_int CryptoSystem::euclidean_algo(mp::cpp_int x, mp::cpp_int y) {
mp::cpp_int remainder = 0;
while (true) {
remainder = x % y;
if (remainder == 0) {
break;
}
x = y;
y = remainder;
}
return y;
}
mp::cpp_int CryptoSystem::get_rand_num() {
rd::mt19937 base_gen(clock());
rd::independent_bits_engine<rd::mt19937, 32, mp::cpp_int> gen(base_gen);
return gen();
}
mp::cpp_int CryptoSystem::extended_euclidean_algo(mp::cpp_int z, mp::cpp_int e) {
std::vector<mp::cpp_int> x = std::vector<mp::cpp_int>();
std::vector<mp::cpp_int> y = std::vector<mp::cpp_int>();
std::vector<mp::cpp_int> w = std::vector<mp::cpp_int>();
std::vector<mp::cpp_int> k = std::vector<mp::cpp_int>();
// initialize
x.emplace_back(1);
y.emplace_back(0);
x.emplace_back(0);
y.emplace_back(1);
w.emplace_back(z);
w.emplace_back(e);
k.emplace_back(0);
int i = 1;
while (w.back() != 1) {
k.emplace_back(w.at(i-1) / w.at(i));
i++;
x.emplace_back(x.at(i-2) - (k.at(i-1)*x.at(i-1)));
y.emplace_back(y.at(i-2) - (k.at(i-1)*y.at(i-1)));
w.emplace_back(w.at(i-2) - (k.at(i-1)*w.at(i-1)));
}
if (y.back() < 0) {
return y.back() + z;
}
return y.back();
}