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#include<stdio.h> #include<stdlib.h> #include<string.h> int isPrime(int n); int
eIsStandard(int e,int fai_n); int gcd(int m,int n); int countD(int e,int n); int
* inputString(int &m_len);//将输入的一串字符转换为一组数字，放在整型数组里面 int encodeString(int e,int
n); //加密函数 int decodeString(int d,int n); //解密函数 int outputString(int * intStr,
int d,int n,int len); long long powMod(long long a,long long b,long long c); int
main() { while(1) { int p,q,e,d,n,fai_n; printf("请输入p,q的值\n"); int flag1,flag2,
flag3; scanf("%d%d",&p,&q); flag1 = isPrime(p); flag2 = isPrime(q);
//printf("flag1 p :%d flag2 q :%d\n",flag1,flag2); if(flag1==1&&flag2==1) { n =
p*q; fai_n = (p-1)*(q-1); printf("p:%d q:%d n:%d fai_n:%d\n",p,q,n,fai_n);
printf("请输入e的值!\n"); scanf("%d",&e); //判断e是否满足 1<e< fai(n)，且gcd(fai(n),e)=1
flag3=eIsStandard(e,fai_n); if(flag3==1){ printf("输入的e符合条件！\n"); //计算d，满足 d·e≡1
mod fai(n) d = countD(e,fai_n); printf("d: %d\n",d); //现在
以{e,n}为公开钥,{d,p,q}为秘密钥 齐全了 /*inputString(); encodeString(); decodeString();*/
int choice; printf("请选择：1，加密 2，解密\n"); scanf("%d",&choice); getchar(); switch(
choice){ case 1: encodeString(e,n); break; case 2: decodeString(d,n); break; } }
else{ printf("输入的e不符合条件！\n"); printf("\n"); } }else{ printf("\n"); continue; } }
} int isPrime(int n) { int flag,i; if(n<2) { flag = 0; } else { for(i=2; i<n; i
++) { if(n%i==0) { // flag = 0; break; } } if(i<n) { printf("%d不是素数！\n",n); flag
= 0; } else { printf("%d是素数！\n",n); flag = 1; } } return flag; } int eIsStandard
(int e,int fai_n){ int flag = 0; int flag2= 0; if(e>1&&e<fai_n){ flag2 = gcd(e,
fai_n); if(flag2==1){ flag = 1; }else{ printf("最大公因数不为1！\n"); } } else { printf(
"不在范围内！\n"); flag = 0; } return flag; } int gcd(int m,int n){ int flag = 0; int
t,r; if(m<n){ //确保是大数除小数 t = m; m = n; n = t; } while((m%n)!=0){ //辗转相除 r = m%
n; m = n; n = r; } if(n==1){ flag = 1; //最大公因数为1，故互素 }else{ flag = 0; //不互素 }
return flag ; } int countD(int e,int n){ int k=0,d; for (k = 0; (k*n + 1) % e !=
0; k++); if ((k*n + 1) % e == 0) d = (k*n + 1) / e; //d * e ≡ 1 (mod Φ(n))
return d; } int * inputString(int &m_len){ printf("请输入您要加密的字符串!\n"); char * s =
(char *)malloc(sizeof(char)*1000); scanf("%[^\n]s",s); int len= strlen(s); m_len
= len; printf("strlen: %d\n",len); int * intStr = (int * )malloc(sizeof(int)*len
); int i=0; for(i=0;i<len;i++){ if(s[i]==' '){ intStr[i]=0; }else if(s[i]>='A'&&
s[i]<='Z'){ intStr[i]=s[i]-64; }else if(s[i]>='a'&&s[i]<='z'){ intStr[i]=s[i]-96
; } } printf("intStr的内容！\n"); for(i=0;i<len;i++){ printf("%d,",intStr[i]); }
printf("\n"); //getchar(); // int * p = NULL; return intStr; } int encodeString(
int e,int n){ printf("e:%d n:%d\n",e,n); int m_len =0; int * intStr =
inputString(m_len); // printf("m_len:%d intstr[0]:%d\n",m_len,intStr[0]); int *
encodeRes= (int *)malloc(sizeof(int)*m_len); int i=0; for(i=0;i<m_len;i++){
//printf("intStr[i]^e:%d\n",intStr[i]^e); encodeRes[i]=(int)powMod((long long)
intStr[i],(long long)e,(long long)n); } printf("encodeRes:\n"); for(i=0;i<m_len;
i++){ //printf("intStr: %d\n",intStr[i]); if(i==m_len-1){ printf("%d",encodeRes[
i]); }else{ printf("%d,",encodeRes[i]); } } printf("\n"); return 0; } int
decodeString(int d,int n){ printf("d:%d n:%d\n",d,n); printf("请输入需解密字母的个数：\n");
int num; scanf("%d",&num); getchar(); int *intStr = (int *)malloc(sizeof(int)*
num); int i=0; printf("请逐个输入密文：\n"); for(i=0;i<num;i++){ scanf("%d",&intStr[i]);
} /*printf("输入的密文为：\n"); for(i=0;i<num;i++){ printf("%d,",intStr[i]); }*/ printf
("\n"); outputString(intStr,d,n,num); return 0; } int outputString(int * intStr,
int d,int n,int len){ //printf("d:%d n:%d len:%d",d,n,len); printf("\n"); int i=
0; /*printf("intStr:\n"); for(i=0;i<len;i++){ printf("%d,",intStr[i]); }*/ int *
decodeRes= (int*)malloc(sizeof(int)*len); for(i=0;i<len;i++){ decodeRes[i]=(int
)powMod((long long)intStr[i],(long long)d,(long long)n); } printf(
"\ndecodeRes!\n"); /*for(i=0;i<len;i++){ printf("%d,",decodeRes[i]); }*/ char *
outputString= (char *)malloc(sizeof(char)*len); for(i=0;i<len;i++){ if(decodeRes
[i]==0){ outputString[i]=' '; }else if(decodeRes[i]>=1&&decodeRes[i]<=26){
outputString[i]=decodeRes[i]+64; } } for(i=0;i<len;i++){ printf("%c",
outputString[i]); } printf("\n"); } long long powMod(long long a,long long b,
long long c) { long long result = 1; //a = a%c; while(b>0) { if(b % 2 == 1)
result= (result * a )% c; b >>=1; //b = b/2; a = (a * a )% c; } return result; }