OldRSApgm

rsa1.cpp

//RSA暗号化プログラム

#include <iostream>
#include <vector>
#include <random>
#include <time.h>
#define unsigned unsigned long long
using namespace std;

//最大公約数を求める
unsigned gcd(unsigned m, unsigned n)
{
    // 引数に0がある際は例外処理をする。
    try{
        if ((0==m)||(0==n)) throw m;
    }
    catch(...){
        cout<<"there has 0."<<endl;
        return 0;
    }
    // ユークリッド互除法
    while(m!=n)
    {
        if(m>n){m=m-n;}
        else{n = n - m;}
    }
    return m;
}

class key{
public:
    unsigned publickey;
    unsigned rule;
};

int main(int argc, char* argv[])
{
    //乱数作成器
    random_device rnd;
    //素数格納オブジェクト
    vector<unsigned> prime;
    int flag=0;
    //公開鍵オブジェクト
    key openkey;
    
    //vectorに３ケタの素数を格納
    for(unsigned i=10;i<100;i++){
        for(unsigned j=2;j<i/2;j++){
            if(i%j==0){
                flag=1;
            }
        }
        if(flag==0){
            prime.push_back(i);
        }
        flag=0;
    }

    unsigned a,b;
    
    //２つの素数をランダムにvectorから選出
    do{
        a=prime[rnd()%prime.size()];
        b=prime[rnd()%prime.size()];
    }while(a==b);

    //公開鍵の一つとなるルールを作成
    openkey.rule=a*b;

    //もう一つの公開鍵を求める
    
    while(1){
        openkey.publickey=rnd()%((unsigned)openkey.rule-1);
        if(gcd(openkey.publickey,(a-1)*(b-1))==1){
            break;
        }
        openkey.publickey=0;
    }
    
    //秘密鍵を求める
    unsigned privatekey;
    
    for(int i=2;(int)openkey.publickey*i%((a-1)*(b-1))!=1;i++){
        privatekey=i+1;
    }
    
    cout<<"public key1: "<<openkey.publickey<<endl;
    cout<<"private key: "<<privatekey<<endl;
    cout<<"public key2: "<<openkey.rule<<endl;
    cout<<"prime numbers: "<<a<<"  "<<b<<endl<<endl;
    
    
    cout<<"example:"<<endl;
    //実行例(1〜100)
    unsigned abb=rnd()%100+1;
    unsigned encryption=abb;
    cout<<"original number: "<<abb<<endl;
    
    //暗号化
    for(unsigned i=1;i<openkey.publickey;i++){
        abb*=encryption;
        while(abb>=openkey.rule)abb-=openkey.rule;
    }
    cout<<"after encryption: "<<abb<<endl;
    cout<<"start decryption"<<endl;
    clock_t start=clock();    
    //複合化
    unsigned decryption=abb;
    for(unsigned i=1;i<privatekey;i++){
        abb*=decryption;
        while(abb>=openkey.rule)abb-=openkey.rule;
    }
    
    clock_t end=clock();
    
    cout<<"after decryption: "<<abb<<endl;

    cout<<"passed time between decryption:"<<(double)(end-start)/CLOCKS_PER_SEC<<"seconds"<<endl;
    return 0;
}