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DES2.cpp
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/*
* @Descripttion:
* @version:
* @Author: MuzhiYing
* @Date: 2022-03-23 16:39:46
* @LastEditors: MuzhiYing
* @LastEditTime: 2022-03-23 16:39:47
*/
/*
* @Descripttion: refer to "密码编码与信息安全:C++实践"
* @version:
* @Author: MuzhiYing
* @Date: 2022-03-23 14:36:55
* @LastEditors: MuzhiYing
* @LastEditTime: 2022-03-23 16:09:42
*/
#include <iostream>
#include <string>
#include <vector>
using std::vector;
using namespace std;
// using namespace std::cout;
// using namespace std::endl;
// using namespace std::string;
// unsigned int 刚好是 64bit = 8Byte = 8 * char
class DES
{
public:
DES(); // 构造函数
// function
void setKey(string k); // 设置初始密钥的函数
void setPlainText(string p); // 设置明文的函数
unsigned long long permutations(unsigned long long num, const int p[], int pmax, int n); // 用于密钥生成、加解密过程的各类置换的函数
void genEncKey(); // 生成加密、解密的子密钥的过程
unsigned long long SBoxes(unsigned long long num); // S盒计算
void encryption(); // 用于加密函数
void decryption(); // 用于解密函数
void showBinary(unsigned long long num); // 将数据以二进制形式显示的函数，用于检查数据计算过程
void showResult(); // 用于显示解密，解密结果的函数
string text;
void getPlainText(){
cout<<"using 8 characters, input ur cipherText:\t"<<text<<endl;
}
void getDeCipherText(){
cout<<"using 8 characters, input ur deCipherText:\t"<<decipherText<<endl;
}
private:
unsigned long long keyShift(unsigned long long k, int n);
unsigned long long key; // 输入的密钥
unsigned long long plainText; // 明文
unsigned long long cipherText; // 密文
unsigned long long decipherText; // 经过解密后的密文，理论上应该等于明文
unsigned long long encKey[16]; // 由密钥生成的16个子密钥
static const int IP[64]; // 初始IP置换
static const int IPI[64]; // IP置换的逆置换
static const int keyIP[56]; // 密钥置换数组，将密钥从64bit->56bit
static const int encKeyRound[16]; // 生成子密钥时左移数组
static const int CP[48]; // 密钥压缩置换数组，将密钥从56bit->48bit
static const int EP[48]; // 扩展置换的数组，将明文从32bit->48bit
static const int SBox[32][16]; // S盒运算
static const int P[32]; // S盒运算后的P置换数组
};
/// 初始化
DES::DES(){
key = 0;
plainText = 0;
cipherText = 0;
decipherText = 0;
}
/// 用于加密。将进来的明文进行ip置换，64bit->64bit
const int DES::IP[64] = {58, 50, 42, 34, 26, 18, 10, 2,
60, 52, 44, 36, 28, 20, 12, 4,
62, 54, 46, 38, 30, 22, 14, 6,
64, 56, 48, 40, 32, 24, 16, 8,
57, 49, 41, 33, 25, 17, 9, 1,
59, 51, 43, 35, 27, 19, 11, 3,
61, 53, 45, 37, 29, 21, 13, 5,
63, 55, 47, 39, 31, 23, 15, 7};
/// 用于加密。将经过16轮轮变换的text进行ipi置换，即ip逆置换，64bit->64bit
const int DES::IPI[64] = {40, 8, 48, 16, 56, 24, 64, 32,
39, 7, 47, 15, 55, 23, 63, 31,
38, 6, 46, 14, 54, 22, 62, 30,
37, 5, 45, 13, 53, 21, 61, 29,
36, 4, 44, 12, 52, 20, 60, 28,
35, 3, 43, 11, 51, 19, 59, 27,
34, 2, 42, 10, 50, 18, 58, 26,
33, 1, 41, 9, 49, 17, 57, 25};
/// 用于生成密钥。将密钥PC1置换，64bit->56bit
const int DES::keyIP[56] = {57, 49, 41, 33, 25, 17, 9,
1, 58, 50, 42, 34, 26, 18,
10, 2, 59, 51, 43, 35, 27,
19, 11, 3, 60, 52, 44, 36,
63, 55, 47, 39, 31, 23, 15,
7, 62, 54, 46, 38, 30, 22,
14, 6, 61, 53, 45, 37, 29,
21, 13, 5, 28, 20, 12, 4};
/// 用于生成密钥。生成子密钥时左移数组个数
const int DES::encKeyRound[16] = {1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1};
/// 用于生成密钥。PC2置换，56bit->48bit
const int DES::CP[48] = {14, 17, 11, 24, 1, 5,
3, 28, 15, 6, 21, 10,
23, 19, 12, 4, 26, 8,
16, 7, 27, 20, 13, 2,
41, 52, 31, 37, 47, 55,
30, 40, 51, 45, 33, 48,
44, 49, 39, 56, 34, 53,
46, 42, 50, 36, 29, 32};
/// 用于加密中轮运算。E扩展置换，32bit->48bit
const int DES::EP[48] = {32, 1, 2, 3, 4, 5,
4, 5, 6, 7, 8, 9,
8, 9, 10, 11, 12, 13,
12, 13, 14, 15, 16, 17,
16, 17, 18, 19, 20, 21,
20, 21, 22, 23, 24, 25,
24, 25, 26, 27, 28, 29,
28, 29, 30, 31, 32, 1};
/// 用于加密中轮运算。S盒置换，48bit->32bit
const int DES::SBox[32][16] = {
14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7, //S1
0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8,
4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0,
15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13,
15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10, //S2
3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5,
0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15,
13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9,
10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8, //S3
13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1,
13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7,
1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12,
7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15, //S4
13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9,
10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4,
3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14,
2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9,
14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6,
4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14,
11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3, //S5
12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11,
10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8,
9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6,
4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13, //S6
4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1,
13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6,
1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2,
6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12,//S7
13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7,
1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2,
7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8,
2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11 //S8
};
/// 用于加密中轮运算。P盒置换，32bit->32bit
const int DES::P[32] = {16, 7, 20, 21, 29, 12, 28, 17,1, 15, 23, 26, 5, 18, 31, 10,
2, 8, 24, 14, 32, 27, 3, 9, 19, 13, 30, 6, 22, 11, 4, 25};
/// 输入密钥为8Byte的字符串，转换为unsigned long long 类型 64bit
void DES::setKey(string k)
{
int i ;
unsigned long long c;
for (i = 0; i< 8; i++){
c = k[i];
key = (c<<(7-i) * 8) | key; // key等于左移后的c
}
}
/// 输入明文为8Byte的字符串，转换为unsigned long long 类型 64bit
void DES::setPlainText(string p){
int i;
unsigned long long c;
for (i = 0; i< 8; i++){
c = p[i];
plainText = (c<<(7-i)*8) | plainText;
}
}
/// 生成子密钥
void DES::genEncKey(){
unsigned long long gkey;
gkey = permutations(key, keyIP, 64, 56); // 密钥初始置换。64bit->56bit
int i;
for(i=0; i<16; i++){
gkey = keyShift(gkey, encKeyRound[i]); // 左移
encKey[i] = permutations(gkey, CP, 56, 48); // 密钥压缩置换。56bit->48bit
}
}
/// 密钥循环左右移
unsigned long long DES::keyShift(unsigned long long k, int n){
unsigned long long tempKey = 0;
unsigned long long L, R;
L = (k&0xFFFFFFF0000000LL)>>28;
//cout<<"L:"<<L<<endl;
R = k&0x0000000FFFFFFF;
if(n == 1){
L = ((L&0x7FFFFFF)<<1) | ((L>>27)&1);
R = ((R&0x7FFFFFF)<<1) | ((R>>27)&1);
tempKey = (L<<28) | R;
}else if(n==2){
L = ((L&0x3FFFFFF)<<2) | ((L>>26)&3);
R = ((R&0x7FFFFFF)<<2) | ((R>>26)&3);
tempKey = (L<<28) | R;
}
return tempKey;
}
/// 根据数组要求，实现置换
unsigned long long DES::permutations(unsigned long long num, const int p[], int pmax, int n){
unsigned long long temp = 0;
int i;
for(i=0;i<n;i++){
temp <<= 1;
temp |= (num >> (pmax - p[i])) & 1;
}
return temp;
}
/// S盒运算
unsigned long long DES::SBoxes(unsigned long long num){
int i;
unsigned long long temp;
unsigned long long result = 0;
for (i=0; i<8; ++i){
temp = (num >> ((7-i) * 6)) & 0x3F;
int x = ((temp>>4) & 0x2) | (temp & 0x1) + i*4;
int y = (temp>>1) & 0xF;
temp = SBox[x][y];
temp = temp << ((7-i)*4);
result |= temp;
}
return result;
}
/// 加密总过程
void DES::encryption(){
unsigned long long temp = permutations(plainText, IP, 64, 64);
int i;
unsigned long long L, R, tempR;
L = (temp & 0xFFFFFFFF00000000LL) >> 32;
R = (temp & 0x00000000FFFFFFFFLL);
tempR = R;
for(i = 0; i<16; i++){
tempR = permutations(R, EP, 32, 48);
tempR = tempR ^ encKey[i];
tempR = SBoxes(tempR);
tempR = permutations(tempR, P, 32, 32);
tempR ^= L;
L = R;
R = tempR;
cout<<"L["<<i+1<<"]:"<<L<<";R["<<i+1<<"]:"<<R<<endl;
}
temp = (R<<32) | L;
temp = permutations(temp, IPI, 64, 64);
cipherText = temp;
}
/// 解密总过程
void DES::decryption(){
unsigned long long temp = permutations(cipherText, IP, 64, 64);
int i;
unsigned long long L, R, tempR;
L = (temp & 0xFFFFFFFF00000000LL) >> 32;
R = (temp & 0x00000000FFFFFFFFLL);
tempR = R;
for(i = 0; i<16; i++){
tempR = permutations(R, EP, 32, 48);
tempR = tempR ^ encKey[15-i]; // 密钥生成方顺序不同
tempR = SBoxes(tempR);
tempR = permutations(tempR, P, 32, 32);
tempR ^= L;
L = R;
R = tempR;
}
temp = (R<<32) | L;
temp = permutations(temp, IPI, 64, 64);
decipherText = temp;
}
/// 二进制结果展示
void DES::showBinary(unsigned long long num){
std::vector<int> v;
do{
v.push_back(num % 2);
num = (num - num%2) / 2;
}while(num != 0);
for(int i=(v.size()-1); i>=0; i--){
cout<<v[i];
}
cout<<endl;
}
/// 展示结果
void DES::showResult(){
int i;
cout << "key = ";
for(i = 0; i< 8; i++){
cout << (char) ((key>>(7-i) * 8)&0xFF);
}
cout << endl;
cout << "plainText = ";
for (i = 0; i< 8; i++){
cout << (char) ((plainText >> (7-i) * 8)& 0xFF);
}
cout << endl;
cout << "cipherText = ";
for (i = 0; i< 8; i++){
cout << (char) ((cipherText>>(7-i) *8)&0xFF);
}
cout << endl;
cout << "decipherText = ";
for (i = 0; i< 8; i++){
cout << (char)((decipherText>>(7-i)*8)&0xFF);
}
cout << endl;
}
/// main
int main(int argc, char const *argv[])
{
DES des;
des.setKey("01234567");
int i = 0;
do {
cout << "[0] exit;\n[1] example\n[2] get your cipherText\n[3] get your decipherText" << endl;
cin >> i;
if (i == 0)
{
cout << "thanks for ur using, bye";
}
else if (i == 1){
des.setPlainText("76543210");
des.genEncKey();
des.encryption();
des.decryption();
des.showResult();
}else if (i == 2){
des.getPlainText();
des.setPlainText(des.text);
des.genEncKey();
des.encryption();
des.decryption();
des.showResult();
}else if (i == 3){
}else{
cout << "illegal, bye";
break;
}
}while (i);
return 0;
}