RSA-easy.rar_easy

#include <iostream> #include <cmath> #include <cstdio> using namespace std; typedef int Elemtype; Elemtype p,q,e; Elemtype fn; Elemtype m,c; int flag = 0; typedef void (*Msghandler) (void); struct MsgMap { char ch; Msghandler handler; }; /* 公钥 */ struct PU { Elemtype e; Elemtype n; } pu; /* 私钥 */ struct PR { Elemtype d; Elemtype n; } pr; /* 判定一个数是否为素数 */ bool test_prime(Elemtype m) { if (m <= 1) { return false; } else if (m == 2) { return true; } else { for(int i=2; i<=sqrt(m); i++) { if((m % i) == 0) { return false; break; } } return true; } } /* 将十进制数据转化为二进制数组 */ void switch_to_bit(Elemtype b, Elemtype bin[32]) { int n = 0; while( b > 0) { bin[n] = b % 2; n++; b /= 2; } } /* 候选菜单，主界面 */ void Init() { cout<<"*********************************************"<<endl; cout<<"*** Welcome to use RSA-oaep encoder ***"<<endl; cout<<"*** a.about ***"<<endl; cout<<"*** e.encrypt ***"<<endl; cout<<"*** d.decrypt ***"<<endl; cout<<"*** s.setkey ***"<<endl; cout<<"*** q.quit ***"<<endl; cout<<"**********************************by*Terry***"<<endl; cout<<"press a key:"<<endl; } /* 将两个数排序，大的在前面*/ void order(Elemtype &in1, Elemtype &in2) { Elemtype a = ( in1 > in2 ? in1 : in2); Elemtype b = ( in1 < in2 ? in1 : in2); in1 = a; in2 = b; } /* 求最大公约数 */ Elemtype gcd(Elemtype a, Elemtype b) { order(a,b); int r; if(b == 0) { return a; } else { while(true) { r = a % b; a = b; b = r; if (b == 0) { return a; break; } } } } /* 用扩展的欧几里得算法求乘法逆元 */ Elemtype extend_euclid(Elemtype m, Elemtype bin) { order(m,bin); Elemtype a[3],b[3],t[3]; a[0] = 1, a[1] = 0, a[2] = m; b[0] = 0, b[1] = 1, b[2] = bin; if (b[2] == 0) { return a[2] = gcd(m, bin); } if (b[2] ==1) { return b[2] = gcd(m, bin); } while(true) { if (b[2] ==1) { return b[1]; break; } int q = a[2] / b[2]; for(int i=0; i<3; i++) { t[i] = a[i] - q * b[i]; a[i] = b[i]; b[i] = t[i]; } } } /* 快速模幂算法 */ Elemtype modular_multiplication(Elemtype a, Elemtype b, Elemtype n) { Elemtype f = 1; Elemtype bin[32]; switch_to_bit(b,bin); for(int i=31; i>=0; i--) { f = (f * f) % n; if(bin[i] == 1) { f = (f * a) % n; } } return f; } /* 产生密钥 */ void produce_key() { cout<<"input two primes p and q:"; cin>>p>>q; while (!(test_prime(p)&&test_prime(q))){ cout<<"wrong input,please make sure two number are both primes!"<<endl; cout<<"input two primes p and q:"; cin>>p>>q; }; pr.n = p * q; pu.n = p * q; fn = (p - 1) * (q - 1); cout<<"fn = "<<fn<<endl; cout<<"input e :"; cin>>e; while((gcd(fn,e)!=1)) { cout<<"e is error,try again!"; cout<<"input e :"; cin>>e; } pr.d = (extend_euclid(fn,e) + fn) % fn; pu.e = e; flag = 1; cout<<"PR.d: "<<pr.d<<" PR.n: "<<pr.n<<endl; cout<<"PU.e: "<<pu.e<<" PU.n: "<<pu.n<<endl; } /* 加密 */ void encrypt() { if(flag == 0) { cout<<"setkey first:"<<endl; produce_key(); } cout<<"input m:"; cin>>m; c = modular_multiplication(m,pu.e,pu.n); cout<<"c is:"<<c<<endl; } /* 解密 */ void decrypt() { if(flag == 0) { cout<<"setkey first:"<<endl; produce_key(); } cout<<"input c:"; cin>>c; m = modular_multiplication(c,pr.d,pr.n); cout<<"m is:"<<m<<endl; } /* 版权信息 */ void about() { cout<<"*********************************************"<<endl; cout<<"*** by Terry ***"<<endl; cout<<"*** copyright 2010,All rights reserved by ***"<<endl; cout<<"*** Terry,technology supported by weizuo !***"<<endl; cout<<"*** If you have any question, please mail ***"<<endl; cout<<"*** to 18679376@qq.com ! ***"<<endl; cout<<"*** Computer of science and engineering ***"<<endl; cout<<"*** XiDian University 2010-4-29 ***"<<endl; cout<<"*********************************************"<<endl; cout<<endl<<endl; Init(); } /* 消息映射 */ MsgMap Messagemap[] = { {'a',about}, {'s',produce_key}, {'d',decrypt}, {'e',encrypt}, {'q',NULL} }; /* 主函数，提供循环 */ int main() { Init(); char d; while((d = getchar())!='q') { int i = 0; while(Messagemap[i].ch) { if(Messagemap[i].ch == d) { Messagemap[i].handler(); break; } i++; } } return 0; }