decimal数据加密

‘壹’ C++ ASCII 加密

#include <stdio.h>
#include <string.h>

// 将十进制数decimal转换为k进制数，并以字符串形式存放在字符数组s中
char *CountRule(int decimal,int k,char *s) {
int ch,i,n;
for(n = 0; decimal > 0; ++n) {
s[n] = decimal%k + '0';
decimal /= k;
}
s[n] = '\0';
for(i = 0; i < n/2; ++i) {
ch = s[i];
s[i] = s[n - i - 1];
s[n - i - 1] = ch;
}
return s;
}

// 将k进制串转换为十进制数，并以整数返回
unsigned Transform(char s[], int k) {
int n = 1,j,len;
unsigned num = 0;
len = strlen(s);
for(j = len - 1;j >= 0; j--) {
num += n*(s[j] - '0');
n *= k;
}
return num;
}

unsigned char *Encrypt(unsigned char *plaintext,char *key,unsigned char *cryptogram) {
int i,j,klen,blen;
char ch,binarystr[9];
unsigned char *p = plaintext;
unsigned char *c = cryptogram;
klen = strlen(key);
for(i = 0; p[i]; ++i) {
c[i] = p[i] - (key[i%klen] - '0'); // 初步加密
CountRule(c[i],2,binarystr); // 将数值s[i]转换为二进制串
blen = strlen(binarystr);
if(blen < 8) {
for(j = blen; j >= 0; --j) // 如果binarystr不够8位，空位留前面
binarystr[j + 8 - blen] = binarystr[j];
for(j = 0; j < 8 - blen; ++j) // 然后在前面填入'0'
binarystr[j] = '0';
}
for(j = 0; j < 8; j += 2) { // 实施核心加密过程:交换相邻奇偶位
ch = binarystr[j];
binarystr[j] = binarystr[j + 1];
binarystr[j + 1] = ch;
}
c[i] = Transform(binarystr,2); // 再把串转回到整数
}
c[i] = '\0';
return (unsigned char *)c;
}

unsigned char *Decrypt(unsigned char *cryptogram,char *key,unsigned char *plaintext) {
int i,j,klen,blen;
char ch,binarystr[9];
unsigned char *c = cryptogram;
unsigned char *p = plaintext;
klen = strlen(key);
for(i = 0; c[i]; ++i) { // 核心解密
CountRule(c[i],2,binarystr); // 将数值s[i]转换为二进制串
blen = strlen(binarystr);
if(blen < 8) {
for(j = blen; j >= 0; --j) // 如果binarystr不够8位，空位留前面
binarystr[j + 8 - blen] = binarystr[j];
for(j = 0; j < 8 - blen; ++j) // 然后在前面填入'0'
binarystr[j] = '0';
}
for(j = 0; j < 8; j += 2) { // 实施核心解密过程:交换相邻奇偶位
ch = binarystr[j];
binarystr[j] = binarystr[j + 1];
binarystr[j + 1] = ch;
}
p[i] = Transform(binarystr,2); // 再把串转回为整数
p[i] += (key[i%klen] - '0'); // 再进行初解密
}
p[i] = '\0';
return (unsigned char *)p;
}

int main() {
unsigned char plaintext[] = "东海县文广体局";
unsigned char secret[80],pt[80];
char key[] = "1B01";
printf("明文 : %s\n",plaintext);
Encrypt(plaintext,key,secret);
printf("密文 : %s\n",secret);
Decrypt(secret,key,pt);
printf("明文 : %s\n",pt);
return 0;
}