RSA

#include <iostream>
#include <vector>
#include <cmath>
#include <algorithm>
#include <time.h>
using namespace std;

void output_vector(vector <int> phrase)
{
    for (int i = 0; i < phrase.size(); ++i)
    {
        cout << phrase[i] << ' ';
    }
}
void input_vector(vector <int>& phrase)
{
    int number;
    while (cin >> number)
    {
        phrase.push_back(number);
    }

}
void str_to_vector (string phr, vector <int>& phrase)
{
    for(int i = 0; i < phr.size(); ++i)
    {
        phrase.push_back(phr[i]);
    }
}
void vector_to_str(string& phr, vector <int> phrase)
{
    for(int i = 0; i < phrase.size(); ++i)
    {
        phr += (char)(phrase.size());
    }
}
int gcd2 (int a, int b)
{
    while (b)
    {
        a%=b;
        swap (a,b);
    }
    return a;
}

int calculating__d ( int e, int fi)
{
    int d, k;
    k = 1;
    while ((((k*fi)+1) % e) != 0)
    {
        ++k;
    }
    //bool state = find_any_solution(e,fi,1,)
    d = (((k*fi)+1) / e);
    return d;

}

void prime_number (vector<int>& prime_numbers)
{
    int a = 0;
    vector <bool> numbers(90000,1); // all numbers, true means false, false prime
    for (int i = 2; i < 1000; ++i)
    {
        int p = 0;
        for (int j = 2; j < i; ++j)
        {
            if ((i % j) == 0)
            {
                ++p;
                break;
            }
        }
        if (p == 0)
        {
            prime_numbers.push_back(i);
            //prime_numbers[a] = i;
            ++a;
        }
    }
    /*for (int i = 0; i <= a; ++ i)
    {
        int k = 2;
        while ((prime_numbers[i] * k) < 90000) //resheto erotosphena
        {
            numbers[prime_numbers[i]*k] = 0;
            ++k;
        }
    }
    for (int i = 0; i < 90000; ++i) //addding prime numbers to vector prime_numbers
    {
        if (numbers[i] == 0)
        {
            prime_numbers.push_back(i);
        }

    }*/


}
int f(int p, int q)
{
    return (p - 1)*(q - 1);
}

int pow1 (int r, int p, int n)
{
    int r1;
    r1 = r;
    for (int i = 1; i < p; ++i)
    {
        r = r * r1;
        r = r % n;

    }
    return (r%n);
}

int e_find(int fi)
{
    int l;
    int a;
    l = (rand() % fi);
    a = l;
    while (gcd2(l,fi) != 1)
    {
        l = (rand() % fi);
        a = l;
    }
    return a;

}
void code(vector <int> &m, int n, int e) {
    for (int i = 0; i < m.size(); ++i)
    {
        m[i] = pow1(m[i], e, n);
    }
}
void decode(vector <int> &m, int d, int n)
{
    for (int i = 0; i < m.size(); ++i)
    {
        m[i] = pow1(m[i], d, n);
    }
}
int main() {
    srand(time (0));
    /*vector <int> prime_numbers(0);
    prime_number(prime_numbers);
    for (int i = 0; i < prime_numbers.size (); ++i)
    {
        cout << prime_numbers[i] << endl;
    }*/
    int d, e, p, q, fi;
    unsigned long n;
    char choise;
    string phr;
    vector <int> phrase (0,0);
    /*vector <int> prime_numbers(0);
    prime_number(prime_numbers);
    p = prime_numbers[rand ()%prime_numbers.size ()];
    q = prime_numbers[rand ()%prime_numbers.size ()];
    while ((p!= 2) && (q!= 2))
    {
        p = prime_numbers[rand ()%prime_numbers.size ()];
        q = prime_numbers[rand ()%prime_numbers.size ()];
    }
    n = p * q;
    fi = f(p, q);
    e = e_find (fi);
    calculating__d(e, fi);*/
    cout << "Do you want to send a letter? (Y/N)" << endl;
    cin >> choise;
    if (choise == 'Y')
    {
        cout << "Input your phrase:" << endl;
        cin >> phr;
        str_to_vector (phr, phrase);
        cout << "Input your multiply and open key" << endl;
        cin >> n;
        cin >> e;
        code (phrase, n, e);
        output_vector(phrase);
    }
    if (choise == 'N')
    {
        vector <int> prime_numbers(0);
        prime_number(prime_numbers);
        p = prime_numbers[rand ()%prime_numbers.size ()];
        q = prime_numbers[rand ()%prime_numbers.size ()];
        while ((p== 2) && (q== 2))
        {
            p = prime_numbers[rand ()%prime_numbers.size ()];
            q = prime_numbers[rand ()%prime_numbers.size ()];
        }
        n = p * q;
        fi = f(p, q);
        e = e_find (fi);
        while (e > n)
        {
            e = e_find (fi);
        }
        calculating__d(e, fi);
        cout << "Multiply is " << n << endl;
        cout << "Open key is " << e << endl;
        cout << "Input coded phrase: " << endl;
        input_vector(phrase);
        decode(phrase, d, n);
        cout << "Decoded phrase is: ";
        output_vector(phrase);
    }
    return 0;
}