rsa加密解密.cpp

RSA加密解密

#include <iostream>
#include <stdio.h> 
#include <cstring> 
#include <stdlib.h>
#include <time.h>
using namespace std;

//int p,q,n,t,d,e;

/*int gcd(int x,int y)
{
	return (y==0)? x:gcd(y,x%y);
}*/

/*int co_prime(int a ,int b)
{ 
int c; 
do 
{ 
if(b==1)	return 1;
c=a%b; 
a=b; 
b=c; 
}while(c!=0); 
return 0; 
} */

/*int get_p() 
{
	int i=2;
	//srand(time(NULL));
	p=rand()%100;
	while(i<p && p%i!=0)	i++;
	if (i!=p)	get_p();
	else return p;
}

int get_q()
{
	int i=2;
	q=rand()%100;
	while(i<q && q%i!=0)	i++;
	if (i!=q)	get_q();
	else return q;
}

int get_d_e()
{
	get_p();
	get_q();
	n=p*q;
	t=(p-1)*(q-1);
loop:e=rand()%t%10;
	if (gcd(e,t)==e||gcd(e,t)==t)	e++;
	//while (co_prime(t,e)!=1)	e=e+1;
	for (d=2;d<t;d++)
	{
		if (d*e%t==1)	break;
	}
	cout<<"p="<<p<<endl;
	cout<<"q="<<q<<endl;
	cout<<"t="<<t<<endl;
	cout<<"d="<<d<<endl;
	cout<<"e="<<e<<endl;
	return d,e,n,t;
}*/

#define n 7081			//n=pq
#define t 6912			//(p-1)(q-1)
#define e 1789			//公钥
#define d 85			//私钥


typedef char strtype[10000]; 
int len; 
long nume[10000]; 
int change[126]; 
char antichange[37]; 

void initialize() 
{
	int i; 
	char c; 
	for (i = 11, c = 'A'; c <= 'Z'; c ++, i ++) 
	{
		change[c] = i; 
		antichange[i] = c;
	} 
} 

void changetonum(strtype str) 
{
	int l = strlen(str), i; 
	len = 0; 
	memset(nume, 0, sizeof(nume)); 
	for (i = 0; i < l; i ++) 
	{
		nume[len] = nume[len] * 100 + change[str[i]]; 
		if (i % 2 == 1) len ++; 
	} 
	if (i % 2 != 0) len ++; 
} 

long binamod(long numb, long k) 
{	
	if (k == 0) return 1; 
	long curr = binamod (numb, k / 2); 
	if (k % 2 == 0) 
	return curr * curr % n; 
	else return (curr * curr) % n * numb % n; 
} 

long encode(long numb) 
{
	return binamod(numb, e); 
} 

long decode(long numb) 
{
	return binamod(numb, d); 
} 

main() 
{
	//	get_d_e();
	strtype str;
	int i, a1, a2,input; 
	long curr; 
	initialize(); 
	cout<<"				RSA加密解密"<<endl;
	cout<<"Y.加密	N.解密"<<endl;
	cout<<"请选择:";
	gets(str); 
	if (str[0] == 'Y'||str[0]=='y') 
	{
		cout<<"请输入明文(大写字母):";
		gets(str);
		changetonum(str); 
		cout<<"加密后的密文为:";
		for (i=0; i<len; i++) 
		{
			if (i) putchar('	'); 
			printf(" %ld ", encode(nume[i])); 
		} 
		putchar('\n');
		system("pause");
		system("cls");
	} 
	else 
	{
		cout<<"输入密文个数:";
		cin>>len;
		cout<<"输入密文(十进制数字，每个密文之间用空格分隔):";
		for (i = 0; i < len; i ++) 
		{
			cin>>curr; 
			curr = decode(curr); 
			a1 = curr / 100; 
			a2 = curr % 100; 
			if (a1 != 0)	putchar(antichange[a1]); 
			if (a2 != 0)	putchar(antichange[a2]); 
		} 
	putchar('\n'); 
	} 
	putchar('\n'); 
	return 0; 
}