DES加密c++实现
2019-05-19 本文已影响0人
白鹿夜
DES的C++实现,需要两个文件,一个table.h,一个DES.h
该算法优点:纯位运算实现,速度快,嵌套内部类,实现完全封装,使用简单,只需要传入字节数组即可实现加密解密.
缺点:位运算需要一个一个复杂设计,对于代码理解几乎不可能,定义过多结构体,导致代码过长.
接下来贴源码
DES.h
#pragma once
#include "table.h"
#include <iostream>
/*
*构造方法:传入秘钥(即c字符串),并,将c字符串转化为内部类(DESKey),内部类处理c字符串,转化为能处理的数据结构
*bdata-n,秘钥长度是固定的.
*
*使用方法: 外部调用public函数decode(char*)或者decode(bdata*),鉴于这是一个工具类,我们不需要添加bdata结构对象.
*返回一个bdata-n数组指针.外部调用encode(bdata*)
*
*/
class DES {
public:
typedef struct BDATA64
{
//8*8=64
char bit[8];
}bdata64;
private:
typedef struct BDATA56
{
char bit[7];
}bdata56;
typedef struct BDATA32
{
char bit[4];
}bdata32;
typedef struct BDATA48
{
char bit[6];
}bdata48;
typedef struct BDATA28
{
char bit[4];//28位的bit我们只能用32位的代替,多余的四位用不上.
}bdata28;
class DESKey {
private:
//计算十六轮,每一轮要用的秘钥c0,d0转化为exkey.
int distributeKey(bdata28* c0, bdata28* d0, int times)
{
char table[] = { 0,1,3 };
//赋值三个char,以及四个位
for (int i = 0; i < 3; i++)
{
c0->bit[i] = realkey.bit[i];
d0->bit[3 - i] = realkey.bit[6 - i];
}
char temp = realkey.bit[3];
c0->bit[3] = temp & 0xf0;
d0->bit[0] = temp & 0x0f;
int step = keytable3[times];
char buf = c0->bit[0];
char buf2 = d0->bit[0];
for (int i = 0; i < 3; i++)
{
//theshift是要补入的一位或两位
char theshift = c0->bit[i + 1];
theshift = theshift >> (8 - step);
theshift = theshift & table[step];
c0->bit[i] = c0->bit[i] << step;
c0->bit[i] = c0->bit[i] & (~table[step]);//需要移入的位先置位0
c0->bit[i] = c0->bit[i] | theshift;
//d0
theshift = d0->bit[i + 1];
theshift = theshift >> (8 - step);
theshift = theshift & table[step];
d0->bit[i] = d0->bit[i] << step;
d0->bit[i] = d0->bit[i] & (~table[step]);//置位0
d0->bit[i] = d0->bit[i] | theshift;
}
buf = buf >> (4 - step);
buf = buf & (table[step] << 4);
c0->bit[3] = c0->bit[3] << step;
c0->bit[3] = c0->bit[3] & (~(table[step] << 4));
c0->bit[3] = c0->bit[3] | buf;
buf2 = buf2 >> (4 - step);
buf2 = buf2 & (table[step]);
d0->bit[3] = d0->bit[3] << step;
d0->bit[3] = d0->bit[3] & (~table[step]);
d0->bit[3] = d0->bit[3] | buf2;
d0->bit[0] = d0->bit[0] & 0x0f;//保持d0前四位为0的格式
return 0;
}
int exKey(bdata28 c0, bdata28 d0, bdata48* exkey)
{
char buf;//buf用于暂存当前bit位所在的字节
char table[] = { -128,64,32,16,8,4,2,1 };
for (int i = 0; i < 48; i++)
{
int position = exkeytable[i] - 1;
int row = position / 8;
int offset = position % 8;
if (row >= 3 && offset > 3)
{
buf = d0.bit[row - 3];
}
else
{
buf = c0.bit[row];
}
int answer = buf & table[offset];
if (answer)
{
row = i / 8;
offset = i % 8;
exkey->bit[row] = exkey->bit[row] | table[offset];
}
else
{
row = i / 8;
offset = i % 8;
exkey->bit[row] = exkey->bit[row] & (~table[offset]);
}
}
return 0;
}
int mergeKey(bdata28 c0, bdata28 d0)
{
for (int i = 0; i < 3; i++)
{
realkey.bit[i] = c0.bit[i];
}
for (int i = 4; i < 7; i++)
{
realkey.bit[i] = d0.bit[i - 3];
}
c0.bit[3] = c0.bit[3] & 0xf0;
d0.bit[0] = d0.bit[0] & 0x0f;
realkey.bit[3] = c0.bit[3] | d0.bit[0];
return 0;
}
void keyOperate() {
bdata28 c0, d0;
for (int i = 0; i <= 15; i++) {
distributeKey(&c0, &d0, i);
exKey(c0, d0, &exkey[i]);
mergeKey(c0, d0);
}
}
public:
void showExKey() {
for (int i = 0; i < 16; i++) {
printf("the %d th exkey ", i + 1);
for (int j = 0; j < 6; j++) {
printf("%d ", exkey[i].bit[j]);
}
printf("\n");
}
}
void showRawKey() {
for (int i = 0; i < 8; i++) {
printf("%d ", rawkey.bit[i]);
}
printf("\n");
}
void showRealKey() {
for (int i = 0; i < 7; i++) {
printf("%d ", realkey.bit[i]);
}
printf("\n");
}
bdata56 realkey;
bdata64 rawkey;
bdata48 exkey[16];
DESKey(char* cp)
{
int length = strlen(cp);
length < 8 ? true : length = 8;
for (int i = 0; i < length; i++) {
rawkey.bit[i] = *cp;
cp++;
}
for (int i = length; i < 8; i++) {
rawkey.bit[i] = 0;
cp++;
}
char table[] = { -128,64,32,16,8,4,2,1 };
//rawkey to realkey
for (int i = 0; i < 56; i++)
{
int position = keytable1[i] - 1;
int row = position / 8;
int offset = position % 8;
//我们需要获得他所在的位
int answer = rawkey.bit[row] & table[offset];
//answer确定所选位是否使能
if (answer)
{
row = i / 8;
offset = i % 8;
realkey.bit[row] = realkey.bit[row] | table[offset];
}
else
{
row = i / 8;
offset = i % 8;
realkey.bit[row] = realkey.bit[row] & (~table[offset]);
}
}
keyOperate();
};
};
void ipExchange(bdata64* m);
void extendRdata(bdata32, bdata48*);
void xorEdata(bdata48*, bdata48);
void sBox(bdata48 edata, bdata32* result);
void pExchange(bdata32*);
void unipExchange(bdata64*);
public:
DESKey key;
//返回一个指针,这个指针是bdata类型指针,指向bdata数组的第一个元素.
DES(char* cp) :key(cp) {};
//n是bdata64数量
static void showBdata64InB(bdata64* p, int n);
static void showBdata64InC(bdata64* p, int n);
bdata64* decode(char* p);
bdata64* decode(bdata64* p, int n);
bdata64* encode(char* p);
bdata64* encode(bdata64* p, int n);
};
DES::bdata64* DES::encode(char* p) {
int length = strlen(p);
int num = ((length - 1) / 8) + 1;
bdata64* mingwen = new bdata64[num];
for (int i = 0; i < length; i++) {
mingwen[i / 8].bit[i % 8] = *(p + i);
}
for (int i = length; i < num * 8; i++) {
mingwen[i / 8].bit[i % 8] = 0;
}
return encode(mingwen, num);
}
DES::bdata64* DES::encode(DES::bdata64* pt, int n) {
//我们不希望破坏原来的明文,所以new内存
bdata64* m = new bdata64[n];//密文对象数组
for (int k = 0; k < n; k++) {
bdata64 mt = *(pt + k);//对这个temp对象进行修改.
ipExchange(&mt);//mt被重映射
bdata32 rdata, ldata;
bdata32 SOUT;
bdata48 edata;
for (int i = 0; i <= 15; i++) {
for (int j = 0; j < 4; j++) {
ldata.bit[j] = mt.bit[j];
rdata.bit[j] = mt.bit[j + 4];
}
extendRdata(rdata, &edata);
xorEdata(&edata, key.exkey[i]);
sBox(edata, &SOUT);
pExchange(&SOUT);
for (int j = 0; j < 4; j++) {
mt.bit[j + 4] = SOUT.bit[j] ^ ldata.bit[j];
mt.bit[j] = rdata.bit[j];
}
}
//after the last loop , exchange left and right.
bdata64 temp = mt;
for (int j = 0; j < 4; j++)
{
mt.bit[j + 4] = temp.bit[j];
mt.bit[j] = temp.bit[j + 4];
}
unipExchange(&mt);
m[k] = mt;
}
return m;
}
DES::bdata64* DES::decode(char* p) {
int length = strlen(p);
int num = (length - 1 / 8) + 1;
bdata64* miwen = new bdata64[num];
for (int i = 0; i < length; i++) {
miwen[i / 8].bit[i % 8] = *(p + i);
}
for (int i = length; i < num * 8; i++) {
miwen[i / 8].bit[i % 8] = 0;
}
return decode(miwen, num);
}
DES::bdata64* DES::decode(bdata64* p, int n) {
//我们不希望破坏原来的密文,所以new内存
bdata64* m = new bdata64[n];//明文对象数组
for (int k = 0; k < n; k++) {
bdata64 mt = *(p + k);//对这个temp对象进行修改.
ipExchange(&mt);//mt被重映射
bdata32 rdata, ldata;
bdata32 SOUT;
bdata48 edata;
for (int i = 0; i <= 15; i++) {
for (int j = 0; j < 4; j++) {
ldata.bit[j] = mt.bit[j];
rdata.bit[j] = mt.bit[j + 4];
}
extendRdata(rdata, &edata);
xorEdata(&edata, key.exkey[15 - i]);//这里是关键
sBox(edata, &SOUT);
pExchange(&SOUT);
for (int j = 0; j < 4; j++) {
mt.bit[j + 4] = SOUT.bit[j] ^ ldata.bit[j];
mt.bit[j] = rdata.bit[j];
}
}
//after the last loop , exchange left and right.
bdata64 temp = mt;
for (int j = 0; j < 4; j++)
{
mt.bit[j + 4] = temp.bit[j];
mt.bit[j] = temp.bit[j + 4];
}
unipExchange(&mt);
m[k] = mt;
}
return m;
}
void DES::ipExchange(bdata64* mp) {
bdata64 oldmingwen = *mp;
char table[] = { -128,64,32,16,8,4,2,1 };
for (int i = 0; i < 64; i++)
{
int position = iptable[i] - 1;
int row = position / 8;
int offset = position % 8;
int answer = oldmingwen.bit[row] & table[offset];
if (answer)//该位置1
{
row = i / 8;
offset = i % 8;
mp->bit[row] = mp->bit[row] | table[offset];
}
else//该位置0
{
row = i / 8;
offset = i % 8;
mp->bit[row] = mp->bit[row] & (~table[offset]);
}
}
return;
}
void DES::extendRdata(bdata32 rdata, bdata48* edata) {
char table[] = { -128,64,32,16,8,4,2,1 };
for (int i = 0; i < 48; i++)
{
int position = extendtable[i] - 1;
int row = position / 8;
int offset = position % 8;
int answer = rdata.bit[row] & table[offset];
if (answer)
{
row = i / 8;
offset = i % 8;
edata->bit[row] = edata->bit[row] | table[offset];
}
else
{
row = i / 8;
offset = i % 8;
edata->bit[row] = edata->bit[row] & (~table[offset]);
}
}
return;
}
void DES::xorEdata(bdata48* edata, bdata48 exkey)
{
for (int i = 0; i <= 6; i++)
{
edata->bit[i] = edata->bit[i] ^ exkey.bit[i];
}
return;
}
void DES::unipExchange(bdata64* mingwen) {
bdata64 oldmingwen = *mingwen;
char table[] = { -128,64,32,16,8,4,2,1 };
for (int i = 0; i < 64; i++)
{
int position = iviptable[i] - 1;
int row = position / 8;
int offset = position % 8;
int answer = oldmingwen.bit[row] & table[offset];
if (answer)//该位置1
{
row = i / 8;
offset = i % 8;
mingwen->bit[row] = mingwen->bit[row] | table[offset];
}
else//该位置0
{
row = i / 8;
offset = i % 8;
mingwen->bit[row] = mingwen->bit[row] & (~table[offset]);
}
}
return;
}
void DES::sBox(bdata48 edata, bdata32* result)
{
char S[8] = { 0 };
char table[] = { -128,64,32,16,8,4,2,1 };
//取出第一和第六个bit位,
char temp = edata.bit[0] & table[0];
char temp2 = edata.bit[0] & table[5];
temp = temp >> 6;
temp = temp & table[6];//只保留有用位
temp2 = temp2 >> 2;
char temp3 = temp | temp2;
temp = edata.bit[0] & 120;//其实只要最高位0即可,即取出中间四位
temp = temp >> 3;
S[0] = stable[0][temp3][temp];
temp = edata.bit[0] & table[6];
temp2 = edata.bit[1] & table[3];
temp2 = temp2 >> 4;
temp3 = temp | temp2;
temp = edata.bit[0] & table[7];
temp2 = edata.bit[1] & -32;
temp2 = temp2 >> 5;
temp2 = temp2 & 7;
temp = temp << 3;
temp = temp | temp2;
S[1] = stable[1][temp3][temp];
temp = edata.bit[1] & table[4];
temp2 = edata.bit[2] & table[1];
temp = temp >> 2;
temp2 = temp2 >> 6;
temp3 = temp | temp2;
temp = edata.bit[1] & 7;
temp = temp << 1;
temp2 = edata.bit[2] & 128;
temp2 = temp2 >> 7;
temp2 = temp2 & table[7];//消除移位补位影响
temp = temp | temp2;
S[2] = stable[2][temp3][temp];
temp = edata.bit[2] & table[2];
temp2 = edata.bit[2] & table[7];
temp = temp >> 4;
temp3 = temp | temp2;
temp = edata.bit[2] & 30;
temp = temp >> 1;
S[3] = stable[3][temp3][temp];
//////////////////////////////////////////
temp = edata.bit[3] & table[0];
temp2 = edata.bit[3] & table[5];
temp = temp >> 6;
temp = temp & table[6];//消解移位头部副作用
temp2 = temp2 >> 2;
temp3 = temp | temp2;
temp = edata.bit[3] & 120;//其实只要最高位0即可
temp = temp >> 3;
S[4] = stable[4][temp3][temp];
temp = edata.bit[3] & table[6];
temp2 = edata.bit[4] & table[3];
temp2 = temp2 >> 4;
temp3 = temp | temp2;
temp = edata.bit[3] & table[7];
temp2 = edata.bit[4] & -32;
temp2 = temp2 >> 5;
temp2 = temp2 & 7;
temp = temp << 3;
temp = temp | temp2;
S[5] = stable[5][temp3][temp];
temp = edata.bit[4] & table[4];
temp2 = edata.bit[5] & table[1];
temp = temp >> 2;
temp2 = temp2 >> 6;
temp3 = temp | temp2;
temp = edata.bit[4] & 7;
temp = temp << 1;
temp2 = temp2 >> 7;
temp2 = temp2 & table[7];
temp = temp | temp2;
S[6] = stable[6][temp3][temp];
temp = edata.bit[5] & table[2];
temp2 = edata.bit[5] & table[7];
temp = temp >> 4;
temp3 = temp | temp2;
temp = edata.bit[5] & 30;
temp = temp >> 1;
S[7] = stable[7][temp3][temp];
for (int i = 0; i <= 3; i++)
{
S[i * 2] = S[i * 2] << 4;
result->bit[i] = S[i * 2] | S[i * 2 + 1];
}
}
void DES::pExchange(bdata32 * SOUT)
{
bdata32 backup = *SOUT;
char table[] = { -128,64,32,16,8,4,2,1 };
for (int i = 0; i < 32; i++)
{
int position = ptable[i] - 1;
int row = position / 8;
int offset = position % 8;
int answer = backup.bit[row] & table[offset];
if (answer)//该位置1
{
row = i / 8;
offset = i % 8;
SOUT->bit[row] = backup.bit[row] | table[offset];
}
else//该位置0
{
row = i / 8;
offset = i % 8;
SOUT->bit[row] = backup.bit[row] & (~table[offset]);
}
}
}
void DES::showBdata64InB(bdata64* p, int n) {
char table[] = { -128,64,32,16,8,4,2,1 };
for (int k = 0; k < n; k++) {
bdata64 mingwen = *(p + k);
printf("------\n");
for (int i = 0; i < 64; i++)
{
char buf = mingwen.bit[i / 8] & table[i % 8];
printf("%d ", (buf > 0) ? 1 : 0);
if (i % 8 == 7)
printf("\n");
}
printf("\n");
}
return;
}
void DES::showBdata64InC(bdata64* p, int n) {
for (int k = 0; k < n; k++) {
bdata64 mingwen = *(p + k);
printf("------\n");
for (int i = 0; i < 8; i++) {
printf("%c ", mingwen.bit[i]);
}
printf("\n");
}
}
table.h
#pragma once
//key初始置换表,我们省去了奇偶校验过程
int keytable1[] = { 57,49,41,33,25,17,9,//秘钥置换选择1
1,58,50,42,34,26,18,//56
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,
};
int iptable[] = { 58,50,42,34,26,18,10,2,//初始置换IP
60,52,44,36,28,20,12,4,//64
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,
};
int ptable[] = { //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,
};
int keytable3[] = { 1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1 };
int extendtable[] = { 32,1,2,3,4,5,//密文选择扩展E 48
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,
};
int exkeytable[] = { 14,17,11,24,1,5,//秘钥置换选择2
3,28,15,6,21,10,//56
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,
};
char stable[8][4][16] = {
14,4,13,1,2,15,11,8,3,10,6,12,5,9,0,7,
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,
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,
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,
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,
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,
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,
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,
};
int iviptable[] = {
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,
};
使用示例与说明
#include "DES.h"
#include <iostream>
int main() {
char a[9] = { '1','2','3','4','5','6','7','8','\0' };
char text[10] = "hello DES";
//明文八字节(除去0),所以密文也是正好一个bdata64
//a作为秘钥
DES myDes(a);//a作为秘钥传入构造函数,这里可以直接传一个char数组或者我定义的bdata64数据结构
//加密text
DES::bdata64* secret = myDes.encode(text);
//打印加密后的二进制,可以用于查看
DES::showBdata64InB(secret, 2);//show Bdata64 in binary
//myDes.key.showExKey();这里还可以打印16个秘钥,但我这里注释了,如果想查看把注释取消就是
DES::bdata64* mingwen = myDes.decode(secret, 2);//解密,需要注意后面的int代表几个bdata64,八个字节为一个bdata64,也就你明文长度除以8+1;
DES::showBdata64InC(mingwen, 2);//打印明文
delete secret;
delete mingwen;
getchar();
return 0;
}
