#include <stdio.h>
#include <stdlib.h>
unsigned long prime1,prime2,ee
unsigned long *kzojld(unsigned long p,unsigned long q) //扩展欧几里得算法求模逆
{
unsigned long i=0,a=1,b=0,c=0,d=1,temp,mid,ni[2]
mid=p
while(mid!=1)
{
while(p>q)
{p=p-q mid=pi++}
a=c*(-1)*i+ab=d*(-1)*i+b
temp=aa=cc=temp
temp=bb=dd=temp
temp=pp=qq=temp
i=0
}
ni[0]=cni[1]=d
return(ni)
}
unsigned long momi(unsigned long a,unsigned long b,unsigned long p) //模幂算法
{
unsigned long c
c=1
if(a>p) a=a%p
if(b>p) b=b%(p-1)
while(b!=0)
{
while(b%2==0)
{
b=b/2
a=(a*a)%p
}
b=b-1
c=(a*c)%p
}
return(c)
}
void RSAjiami() //RSA加密函数
{
unsigned long c1,c2
unsigned long m,n,c
n=prime1*prime2
system("cls")
printf("Please input the message：\n")
scanf("%lu",&m)getchar()
c=momi(m,ee,n)
printf("The cipher is：%lu",c)
return
}
void RSAjiemi() //RSA解密函数
{
unsigned long m1,m2,e,d,*ni
unsigned long c,n,m,o
o=(prime1-1)*(prime2-1)
n=prime1*prime2
system("cls")
printf("Please input the cipher：\n")
scanf("%lu",&c)getchar()
ni=kzojld(ee,o)
d=ni[0]
m=momi(c,d,n)
printf("The original message is：%lu",m)
return
}
void main()
{ unsigned long m
char cho
printf("Please input the two prime you want to use:\n")
printf("P=")scanf("%lu",&prime1)getchar()
printf("Q=")scanf("%lu",&prime2)getchar()
printf("E=")scanf("%lu",&ee)getchar()
if(prime1<prime2)
{m=prime1prime1=prime2prime2=m}
while(1)
{
system("cls")
printf("\t*******RSA密码系统*******\n")
printf("Please select what do you want to do:\n")
printf("1.Encrpt.\n")
printf("2.Decrpt.\n")
printf("3.Exit.\n")
printf("Your choice:")
scanf("%c",&cho)getchar()
switch(cho)
{ case '1':RSAjiami()break
case '2':RSAjiemi()break
case '3':exit(0)
default:printf("Error input.\n")break
}
getchar()
}
}
* RSA.H - header file for RSA.C*/
/* Copyright (C) RSA Laboratories, a division of RSA Data Security,
Inc., created 1991. All rights reserved.
*/
int RSAPublicEncrypt PROTO_LIST
((unsigned char *, unsigned int *, unsigned char *, unsigned int,
R_RSA_PUBLIC_KEY *, R_RANDOM_STRUCT *))
int RSAPrivateEncrypt PROTO_LIST
((unsigned char *, unsigned int *, unsigned char *, unsigned int,
R_RSA_PRIVATE_KEY *))
int RSAPublicDecrypt PROTO_LIST
((unsigned char *, unsigned int *, unsigned char *, unsigned int,
R_RSA_PUBLIC_KEY *))
int RSAPrivateDecrypt PROTO_LIST
((unsigned char *, unsigned int *, unsigned char *, unsigned int,
R_RSA_PRIVATE_KEY *))
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <time.h>
#define PRIME_MAX 200 // 生成素数范围
#define EXPONENT_MAX 200 // 生成指数e范围
#define Element_Max 127 // 加密单元的最大值，这里为一个char, 即1Byte
char str_read[100]="hello world !" // 待加密的原文
int str_encrypt[100] // 加密后的内容
char str_decrypt[100] // 解密出来的内容
int str_read_len // str_read 的长度
int prime1, prime2 // 随机生成的两个质数
int mod, eular // 模数和欧拉数
int pubKey, priKey // 公钥指数和私钥指数
// 生成随机素数，实际应用中，这两个质数越大，就越难破解。
int randPrime()
{
int prime, prime2, i
next:
prime = rand() % PRIME_MAX // 随机产生数
if (prime <= 1) goto next // 不是质数，生成下一个随机数
if (prime == 2 || prime == 3) return prime
prime2 = prime / 2 // prime>=4, prime2 的平方必定大于 prime , 因此只检查小于等于prime2的数
for (i = 2i <= prime2i++) // 判断是否为素数
{
if (i * i >prime) return prime
if (prime % i == 0) goto next // 不是质数，生成下一个随机数
}
}
// 欧几里德算法，判断a,b互质
int gcd(int a, int b)
{
int temp
while (b != 0) {
temp = b
b = a % b
a = temp
}
return a
}
//生成公钥指数，条件是 1<e <欧拉数，且与欧拉数互质。
int randExponent()
{
int e
while (1)
{
e = rand() % eularif (e <EXPONENT_MAX) break
}
while (1)
{
if (gcd(e, eular) == 1) return ee = (e + 1) % eularif (e == 0 || e >EXPONENT_MAX) e = 2
}
}
//生成私钥指数
int inverse()
{
int d, x
while (1)
{
d = rand() % eular
x = pubKey * d % eular
if (x == 1)
{
return d
}
}
}
//加密函数
void jiami()
{
str_read_len = strlen(str_read) //从参数表示的地址往后找，找到第一个'\0'，即串尾。计算'\0'至首地址的“距离”，即隔了几个字符，从而得出长度。
printf("密文是：")
for (int i = 0i <str_read_leni++)
{
int C = 1int a = str_read[i], b = a % mod
for (int j = 0j <pubKeyj++) //实现加密
{
C = (C*b) % mod
}
str_encrypt[i] = C
printf("%d ", str_encrypt[i])
}
printf("\n")
}
//解密函数
void jiemi()
{
int i=0 for (i = 0i <str_read_leni++)
{
int C = 1int a = str_encrypt[i], b=a%mod
for (int j = 0j <priKeyj++)
{
C = (C * b) % mod
}
str_decrypt[i] = C
}
str_decrypt[i] = '\0'printf("解密文是：%s \n", str_decrypt)
}
int main()
{
srand(time(NULL))
while (1)
{
prime1 = randPrime()prime2 = randPrime()printf("随机产生两个素数：prime1 = %d , prime2 = %d ", prime1, prime2)
mod = prime1 * prime2printf("模数：mod = prime1 * prime2 = %d \n", mod)if (mod >Element_Max) break// 模数要大于每个加密单元的值
}
eular = (prime1 - 1) * (prime2 - 1) printf("欧拉数：eular=(prime1-1)*(prime2-1) = %d \n", eular)
pubKey = randExponent()printf("公钥指数：pubKey = %d\n", pubKey)
priKey = inverse()printf("私钥指数：priKey = %d\n私钥为 (%d, %d)\n", priKey, priKey, mod)
jiami()jiemi()
return 0
}
