我試圖實現一個簡單的RSA加密/解密過程,我很確定我有正確的方式。儘管在加密後似乎沒有打印出正確的解密值。有任何想法嗎?。這個微小的RSA實現爲什麼會給出錯誤的結果?
//test program
#include <iostream>
#include <string.h>
#include <math.h>
using namespace std;
int gcd(int a, int b);
int main(){
char character = 'A'; //character that is to be encrypted
int p = 7;
int q = 5;
int e = 0; // just initializing to 0, assigning actual e value in the 1st for loop
int n = p*q;
int phi = (p-1)*(q-1);
int d = 0; // " " 2nd for loop
//---------------------------finding 'e' with phi. where "1 < e < phi(n)"
for (int i=2; i < phi; i++){
if (gcd(i,phi) == 1){ //if gcd is 1
e = i;
break;
}
}
//----------------------------
//---------------------------finding 'd'
for (int i = 2; i < phi; i++){
int temp = (e*i)%phi;
if (temp == 1){
d = i;
break;
}
}
printf("n:%d , e:%d , phi:%d , d:%d \n",n,e,phi,d);
printf("\npublic key is:[%d,%d]\n",e,n);
printf("private key is:[%d,%d]\n",d,n);
int m = static_cast<int>(character); //converting to a number
printf("\nconverted character num:%d\n",m);
//Encryption part ie. c = m^e MOD n
int power = pow(m,e); // m^e
int c = power%n; // c = m^e MOD n. ie. encrypted character
printf("\n\nEncrypted character number:%d\n",c);
//decryption part, ie. m = c^d MOD n
power = pow(c,d);
int m2 = power%n;
printf("\n\ndecrypted character number:%d\n",m2);
return 0;
}
int gcd(int a, int b){
int r;
if (a < 0) a = -a;
if (b < 0) b = -b;
if (b > a) {
r = b; b = a; a = r;
}
while (b > 0) {
r = a % b;
a = b;
b = r;
}
return a;
}
(正在使用的素數是5和7,用於測試)
在這裏,我的字符「A」轉換成其數字值這當然是65.當我加密此使用c = m^e MOD n
值(其中m是轉換後的值,即,65)它給我C作爲25.
現在,扭轉過程中,我做m = c^d MOD n
,這使我m
30 ...這確實是不正確,因爲它應該是65,不是?
我究竟在哪裏出錯了?
[編輯]
是我d
計算正確嗎?
如果'e'不爲零,它會工作嗎? – Jay 2011-06-09 14:15:51
'int e = 0'只有一個虛擬的,e用在第一個for循環中要使用的實際e值重寫 – silent 2011-06-09 14:22:39
@Jay同樣用於'int d = 0',我剛初始化它在開始時爲0,以便我可以在第二秒爲循環指定實際的'd'值 – silent 2011-06-09 14:26:15