C++中四种加密算法之DES源代码

DES算法是一种最通用的对称密钥算法，因为算法本身是公开的，所以其安全性在于密钥的安全性。基于密钥的算法通常有两类：对称算法和公开密钥算法。对称算法的对称性体现在加密密钥能够从解密密钥推算出来，反之亦然。下面梳理了C++中四种加密算法之DES源代码，供大家参考借鉴。

在大多数对称算法中，加解密的`密钥是相同的，DES就是这样。可见，对称密钥算法的加解密密钥都是保密的。而公开密钥算法的加密密钥是公开的，解密密钥是保密的。

　　DES具体算法如下：

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/*

Provided by 朱孟斌, National University Of Technology

Email: zmbtsubasa@gmailcom

This product is free for use

*/

//////////////////////////////////////////////////////////////////////////

#ifndef Des_H

#define Des_H

//! enum bool{false,true};

/*!

if bool is not supported,use this or just replace with char and use 1 for true,0 for false;

@see enum {ENCRYPT,DECRYPT};

*/

enum {ENCRYPT,DECRYPT};

/*@brief 16圈子密钥*/

static bool SubKey[2][16][48];// 16圈子密钥

/*@brief 3次DES标志*/

static bool Is3DES;// 3次DES标志

static char Tmp[256];

static char deskey[16];

typedef bool (*PSubKey)[16][48];

class _declspec(dllexport) Des

{

public:

Des();

~Des();

//! Type—ENCRYPT:加密,DECRYPT:解密

/*!

输出缓冲区(Out)的长度 >= ((datalen+7)/8)*8,即比datalen大的且是8的倍数的最小正整数

In 可以= Out,此时加/解密后将覆盖输入缓冲区(In)的内容

当keylen>8时系统自动使用3次DES加/解密,否则使用标准DES加/解密超过16字节后只取前16字节

@see bool Des_Go(char *Out,char *In,long datalen,const char *Key,int keylen,bool Type = ENCRYPT);

*/

bool Des_Go(char *Out,char *In,long datalen,const char *Key,int keylen,bool Type = ENCRYPT);

private:

/*! @brief 标准DES加/解密

@see static void DES(char Out[8], char In[8], const PSubKey pSubKey, bool Type);

*/

static void DES(char Out[8], char In[8], const PSubKey pSubKey, bool Type);//标准DES加/解密

/*! @brief 设置密钥

@see static void SetKey(const char* Key, int len);

*/

static void SetKey(const char* Key, int len);// 设置密钥

/*! @brief 设置子密钥

@see static void SetSubKey(PSubKey pSubKey, const char Key[8]);

*/

static void SetSubKey(PSubKey pSubKey, const char Key[8]);// 设置子密钥

/*! @brief f 函数

@see static void F_func(bool In[32], const bool Ki[48]);

*/

static void F_func(bool In[32], const bool Ki[48]);// f 函数

/*! @brief S 盒代替

@see static void S_func(bool Out[32], const bool In[48]);

*/

static void S_func(bool Out[32], const bool In[48]);// S 盒代替

/*! @brief 变换

@see static void Transform(bool *Out, bool *In, const char *Table, int len);

*/

static void Transform(bool *Out, bool *In, const char *Table, int len);// 变换

/*! @brief 异或

@see static void Xor(bool *InA, const bool *InB, int len);

*/

static void Xor(bool *InA, const bool *InB, int len);// 异或

/*! @brief 循环左移

@see static void RotateL(bool *In, int len, int loop);

*/

static void RotateL(bool *In, int len, int loop);// 循环左移

/*! @brief 字节组转换成位组

@see static void ByteToBit(bool *Out, const char *In, int bits);

*/

static void ByteToBit(bool *Out, const char *In, int bits);// 字节组转换成位组

/*! @brief 位组转换成字节组

@see static void BitToByte(char *Out, const bool *In, int bits);

*/

static void BitToByte(char *Out, const bool *In, int bits);// 位组转换成字节组

};

//////////////////////////////////////////////////////////////////////////

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#endif

　　文件：

//////////////////////////////////////////////////////////////////////////

/*

Provided by 朱孟斌, National University Of Technology

Email: zmbtsubasa@gmailcom

This product is free for use

*/

//////////////////////////////////////////////////////////////////////////

#include "memoryh"

#include "Desh"

//////////////////////////////////////////////////////////////////////////

// initial permutation IP

const static char IP_Table[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

};

// final permutation IP^-1

const static char IPR_Table[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

};

// expansion operation matrix

static const char E_Table[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

};

// 32-bit permutation function P used on the output of the S-boxes

const static char P_Table[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

};

// permuted choice table (key)

const static char Pc1_Table[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

};

// permuted choice key (table)

const static char PC2_Table[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

};

// number left rotations of pc1

const static char LOOP_Table[16] = {

1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1

};

// The (in)famous S-boxes

const static char S_Box[8][4][16] = {

// S1

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,

// S2

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,

// S3

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,

// S4

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,

// S5

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,

// S6

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,

// S7

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,

// S8

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

};

//////////////////////////////////////////////////////////////////////////

// Code starts:

//////////////////////////////////////////////////////////////////////////

Des::Des()

{

}

Des::~Des()

{

}

bool Des::Des_Go(char *Out, char *In, long datalen, const char *Key, int keylen, bool Type)

{

if( !( Out && In && Key && (datalen=(datalen+7)&0xfffffff8) ) )

return false;

SetKey(Key, keylen);

if( !Is3DES ) { // 1次DES

for(long i=0,j=datalen>>3; i<j; ++i,Out+=8,In+=8)

DES(Out, In, &SubKey[0], Type);

} else{ // 3次DES 加密:加(key0)-解(key1)-加(key0) 解密::解(key0)-加(key1)-解(key0)

for(long i=0,j=datalen>>3; i<j; ++i,Out+=8,In+=8) {

DES(Out, In, &SubKey[0], Type);

DES(Out, Out, &SubKey[1], !Type);

DES(Out, Out, &SubKey[0], Type);

}

}

return true;

}

void Des::SetKey(const char* Key, int len)

{

memset(deskey, 0, 16);

memcpy(deskey, Key, len>16?16:len);

SetSubKey(&SubKey[0], &deskey[0]);

Is3DES = len>8 ? (SetSubKey(&SubKey[1], &deskey[8]), true) : false;

}

void Des::DES(char Out[8], char In[8], const PSubKey pSubKey, bool Type)

{

static bool M[64], tmp[32], *Li=&M[0], *Ri=&M[32];

ByteToBit(M, In, 64);

Transform(M, M, IP_Table, 64);

if( Type == ENCRYPT ){

for(int i=0; i<16; ++i) {

memcpy(tmp, Ri, 32);

F_func(Ri, (*pSubKey)[i]);

Xor(Ri, Li, 32);

memcpy(Li, tmp, 32);

}

}else{

for(int i=15; i>=0; --i) {

memcpy(tmp, Li, 32);

F_func(Li, (*pSubKey)[i]);

Xor(Li, Ri, 32);

memcpy(Ri, tmp, 32);

}

}

Transform(M, M, IPR_Table, 64);

BitToByte(Out, M, 64);

}

void Des::SetSubKey(PSubKey pSubKey, const char Key[8])

{

static bool K[64], *KL=&K[0], *KR=&K[28];

ByteToBit(K, Key, 64);

Transform(K, K, PC1_Table, 56);

for(int i=0; i<16; ++i) {

RotateL(KL, 28, LOOP_Table[i]);

RotateL(KR, 28, LOOP_Table[i]);

Transform((*pSubKey)[i], K, PC2_Table, 48);

}

}

void Des::F_func(bool In[32], const bool Ki[48])

{

static bool MR[48];

Transform(MR, In, E_Table, 48);

Xor(MR, Ki, 48);

S_func(In, MR);

Transform(In, In, P_Table, 32);

}

void Des::S_func(bool Out[32], const bool In[48])

{

for(char i=0,j,k; i<8; ++i,In+=6,Out+=4) {

j = (In[0]<<1) + In[5];

k = (In[1]<<3) + (In[2]<<2) + (In[3]<<1) + In[4];

ByteToBit(Out, &S_Box[i][j][k], 4);

}

}

void Des::Transform(bool *Out, bool *In, const char *Table, int len)

{

for(int i=0; i<len; ++i)

Tmp[i] = In[ Table[i]-1 ];

memcpy(Out, Tmp, len);

}

void Des::Xor(bool *InA, const bool *InB, int len)

{

for(int i=0; i<len; ++i)

InA[i] ^= InB[i];

}

void Des::RotateL(bool *In, int len, int loop)

{

memcpy(Tmp, In, loop);

memcpy(In, In+loop, len-loop);

memcpy(In+len-loop, Tmp, loop);

}

void Des::ByteToBit(bool *Out, const char *In, int bits)

{

for(int i=0; i<bits; ++i)

Out[i] = (In[i>>3]>>(i&7)) & 1;

}

void Des::BitToByte(char *Out, const bool *In, int bits)

{

memset(Out, 0, bits>>3);

for(int i=0; i<bits; ++i)

Out[i>>3] |= In[i]<<(i&7);

}

//////////////////////////////////////////////////////////////////////////

// Code ends

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