AES加密算法C++实现

　　我从网上下载了一套AES加密算法的C++实现，代码如下：

（1）aes.h

#ifndef SRC_UTILS_AES_H
#define SRC_UTILS_AES_H

class AES
{
public:
    AES(unsigned char* key);
    virtual ~AES();
    unsigned char* Cipher(unsigned char* input);　　　　// 加密，传入的数组大小必须是16字节
    unsigned char* InvCipher(unsigned char* input);　　// 解密，传入的数组也必须是16字节
    void* Cipher(void* input, int length=);　　　　　　// 可以传入数组，大小必须是16的整数倍，如果不是将会越界操作；如果不传length而默认为0，那么将按照字符串处理，遇'\0'结束
    void* InvCipher(void* input, int length);　　　　　 // 必须传入数组和大小，必须是16的整数倍

private:
    unsigned char Sbox[];
    unsigned char InvSbox[];
    unsigned char w[][][];

    void KeyExpansion(unsigned char* key, unsigned char w[][][]);
    unsigned char FFmul(unsigned char a, unsigned char b);

    void SubBytes(unsigned char state[][]);
    void ShiftRows(unsigned char state[][]);
    void MixColumns(unsigned char state[][]);
    void AddRoundKey(unsigned char state[][], unsigned char k[][]);

    void InvSubBytes(unsigned char state[][]);
    void InvShiftRows(unsigned char state[][]);
    void InvMixColumns(unsigned char state[][]);
};

#endif    // SRC_UTILS_AES_H

（2）aes.cpp

 #include "aes.h"
 #include "string.h"

 AES::AES(unsigned char* key)
 {
     unsigned char sBox[] =
     { /*  0    1    2    3    4    5    6    7    8    9    a    b    c    d    e    f */
         0x63,0x7c,0x77,0x7b,0xf2,0x6b,0x6f,0xc5,0x30,0x01,0x67,0x2b,0xfe,0xd7,0xab,0x76, /**/
         0xca,0x82,0xc9,0x7d,0xfa,0x59,0x47,0xf0,0xad,0xd4,0xa2,0xaf,0x9c,0xa4,0x72,0xc0, /**/
         0xb7,0xfd,0x93,0x26,0x36,0x3f,0xf7,0xcc,0x34,0xa5,0xe5,0xf1,0x71,0xd8,0x31,0x15, /**/
         0x04,0xc7,0x23,0xc3,0x18,0x96,0x05,0x9a,0x07,0x12,0x80,0xe2,0xeb,0x27,0xb2,0x75, /**/
         0x09,0x83,0x2c,0x1a,0x1b,0x6e,0x5a,0xa0,0x52,0x3b,0xd6,0xb3,0x29,0xe3,0x2f,0x84, /**/
         0x53,0xd1,0x00,0xed,0x20,0xfc,0xb1,0x5b,0x6a,0xcb,0xbe,0x39,0x4a,0x4c,0x58,0xcf, /**/
         0xd0,0xef,0xaa,0xfb,0x43,0x4d,0x33,0x85,0x45,0xf9,0x02,0x7f,0x50,0x3c,0x9f,0xa8, /**/
         0x51,0xa3,0x40,0x8f,0x92,0x9d,0x38,0xf5,0xbc,0xb6,0xda,0x21,0x10,0xff,0xf3,0xd2, /**/
         0xcd,0x0c,0x13,0xec,0x5f,0x97,0x44,0x17,0xc4,0xa7,0x7e,0x3d,0x64,0x5d,0x19,0x73, /**/
         0x60,0x81,0x4f,0xdc,0x22,0x2a,0x90,0x88,0x46,0xee,0xb8,0x14,0xde,0x5e,0x0b,0xdb, /**/
         0xe0,0x32,0x3a,0x0a,0x49,0x06,0x24,0x5c,0xc2,0xd3,0xac,0x62,0x91,0x95,0xe4,0x79, /*a*/
         0xe7,0xc8,0x37,0x6d,0x8d,0xd5,0x4e,0xa9,0x6c,0x56,0xf4,0xea,0x65,0x7a,0xae,0x08, /*b*/
         0xba,0x78,0x25,0x2e,0x1c,0xa6,0xb4,0xc6,0xe8,0xdd,0x74,0x1f,0x4b,0xbd,0x8b,0x8a, /*c*/
         0x70,0x3e,0xb5,0x66,0x48,0x03,0xf6,0x0e,0x61,0x35,0x57,0xb9,0x86,0xc1,0x1d,0x9e, /*d*/
         0xe1,0xf8,0x98,0x11,0x69,0xd9,0x8e,0x94,0x9b,0x1e,0x87,0xe9,0xce,0x55,0x28,0xdf, /*e*/
         0x8c,0xa1,0x89,0x0d,0xbf,0xe6,0x42,0x68,0x41,0x99,0x2d,0x0f,0xb0,0x54,0xbb,0x16  /*f*/
     };
     unsigned char invsBox[] =
     { /*  0    1    2    3    4    5    6    7    8    9    a    b    c    d    e    f  */
         0x52,0x09,0x6a,0xd5,0x30,0x36,0xa5,0x38,0xbf,0x40,0xa3,0x9e,0x81,0xf3,0xd7,0xfb, /**/
         0x7c,0xe3,0x39,0x82,0x9b,0x2f,0xff,0x87,0x34,0x8e,0x43,0x44,0xc4,0xde,0xe9,0xcb, /**/
         0x54,0x7b,0x94,0x32,0xa6,0xc2,0x23,0x3d,0xee,0x4c,0x95,0x0b,0x42,0xfa,0xc3,0x4e, /**/
         0x08,0x2e,0xa1,0x66,0x28,0xd9,0x24,0xb2,0x76,0x5b,0xa2,0x49,0x6d,0x8b,0xd1,0x25, /**/
         0x72,0xf8,0xf6,0x64,0x86,0x68,0x98,0x16,0xd4,0xa4,0x5c,0xcc,0x5d,0x65,0xb6,0x92, /**/
         0x6c,0x70,0x48,0x50,0xfd,0xed,0xb9,0xda,0x5e,0x15,0x46,0x57,0xa7,0x8d,0x9d,0x84, /**/
         0x90,0xd8,0xab,0x00,0x8c,0xbc,0xd3,0x0a,0xf7,0xe4,0x58,0x05,0xb8,0xb3,0x45,0x06, /**/
         0xd0,0x2c,0x1e,0x8f,0xca,0x3f,0x0f,0x02,0xc1,0xaf,0xbd,0x03,0x01,0x13,0x8a,0x6b, /**/
         0x3a,0x91,0x11,0x41,0x4f,0x67,0xdc,0xea,0x97,0xf2,0xcf,0xce,0xf0,0xb4,0xe6,0x73, /**/
         0x96,0xac,0x74,0x22,0xe7,0xad,0x35,0x85,0xe2,0xf9,0x37,0xe8,0x1c,0x75,0xdf,0x6e, /**/
         0x47,0xf1,0x1a,0x71,0x1d,0x29,0xc5,0x89,0x6f,0xb7,0x62,0x0e,0xaa,0x18,0xbe,0x1b, /*a*/
         0xfc,0x56,0x3e,0x4b,0xc6,0xd2,0x79,0x20,0x9a,0xdb,0xc0,0xfe,0x78,0xcd,0x5a,0xf4, /*b*/
         0x1f,0xdd,0xa8,0x33,0x88,0x07,0xc7,0x31,0xb1,0x12,0x10,0x59,0x27,0x80,0xec,0x5f, /*c*/
         0x60,0x51,0x7f,0xa9,0x19,0xb5,0x4a,0x0d,0x2d,0xe5,0x7a,0x9f,0x93,0xc9,0x9c,0xef, /*d*/
         0xa0,0xe0,0x3b,0x4d,0xae,0x2a,0xf5,0xb0,0xc8,0xeb,0xbb,0x3c,0x83,0x53,0x99,0x61, /*e*/
         0x17,0x2b,0x04,0x7e,0xba,0x77,0xd6,0x26,0xe1,0x69,0x14,0x63,0x55,0x21,0x0c,0x7d  /*f*/
     };
     memcpy(Sbox, sBox, );
     memcpy(InvSbox, invsBox, );
     KeyExpansion(key, w);
 }

 AES::~AES()
 {

 }

 unsigned char* AES::Cipher(unsigned char* input)
 {
     unsigned char state[][];
     int i,r,c;

     for(r=; r<; r++)
     {
         for(c=; c< ;c++)
         {
             state[r][c] = input[c*+r];
         }
     }

     AddRoundKey(state,w[]);

     for(i=; i<=; i++)
     {
         SubBytes(state);
         ShiftRows(state);
         if(i!=)MixColumns(state);
         AddRoundKey(state,w[i]);
     }

     for(r=; r<; r++)
     {
         for(c=; c< ;c++)
         {
             input[c*+r] = state[r][c];
         }
     }

     return input;
 }

 unsigned char* AES::InvCipher(unsigned char* input)
 {
     unsigned char state[][];
     int i,r,c;

     for(r=; r<; r++)
     {
         for(c=; c< ;c++)
         {
             state[r][c] = input[c*+r];
         }
     }

     AddRoundKey(state, w[]);
     for(i=; i>=; i--)
     {
         InvShiftRows(state);
         InvSubBytes(state);
         AddRoundKey(state, w[i]);
         if(i)
         {
             InvMixColumns(state);
         }
     }

     for(r=; r<; r++)
     {
         for(c=; c< ;c++)
         {
             input[c*+r] = state[r][c];
         }
     }

     return input;
 }

 void* AES::Cipher(void* input, int length)
 {
     unsigned char* in = (unsigned char*) input;
     int i;
     if(!length)        // 如果是0则当做字符串处理
     {
         while(*(in+length++));
         in = (unsigned char*) input;
     }
     for(i=; i<length; i+=)
     {
         Cipher(in+i);
     }
     return input;
 }

 void* AES::InvCipher(void* input, int length)
 {
     unsigned char* in = (unsigned char*) input;
     int i;
     for(i=; i<length; i+=)
     {
         InvCipher(in+i);
     }
     return input;
 }

 void AES::KeyExpansion(unsigned char* key, unsigned char w[][][])
 {
     int i,j,r,c;
     unsigned char rc[] = {0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36};
     for(r=; r<; r++)
     {
         for(c=; c<; c++)
         {
             w[][r][c] = key[r+c*];
         }
     }
     for(i=; i<=; i++)
     {
         for(j=; j<; j++)
         {
             unsigned char t[];
             for(r=; r<; r++)
             {
                 t[r] = j ? w[i][r][j-] : w[i-][r][];
             }
             if(j == )
             {
                 unsigned char temp = t[];
                 for(r=; r<; r++)
                 {
                     t[r] = Sbox[t[(r+)%]];
                 }
                 t[] = Sbox[temp];
                 t[] ^= rc[i-];
             }
             for(r=; r<; r++)
             {
                 w[i][r][j] = w[i-][r][j] ^ t[r];
             }
         }
     }
 }

 unsigned char AES::FFmul(unsigned char a, unsigned char b)
 {
     unsigned char bw[];
     unsigned char res=;
     int i;
     bw[] = b;
     for(i=; i<; i++)
     {
         bw[i] = bw[i-]<<;
         if(bw[i-]&0x80)
         {
             bw[i]^=0x1b;
         }
     }
     for(i=; i<; i++)
     {
         if((a>>i)&0x01)
         {
             res ^= bw[i];
         }
     }
     return res;
 }

 void AES::SubBytes(unsigned char state[][])
 {
     int r,c;
     for(r=; r<; r++)
     {
         for(c=; c<; c++)
         {
             state[r][c] = Sbox[state[r][c]];
         }
     }
 }

 void AES::ShiftRows(unsigned char state[][])
 {
     unsigned char t[];
     int r,c;
     for(r=; r<; r++)
     {
         for(c=; c<; c++)
         {
             t[c] = state[r][(c+r)%];
         }
         for(c=; c<; c++)
         {
             state[r][c] = t[c];
         }
     }
 }

 void AES::MixColumns(unsigned char state[][])
 {
     unsigned char t[];
     int r,c;
     for(c=; c< ; c++)
     {
         for(r=; r<; r++)
         {
             t[r] = state[r][c];
         }
         for(r=; r<; r++)
         {
             state[r][c] = FFmul(0x02, t[r])
                         ^ FFmul(0x03, t[(r+)%])
                         ^ FFmul(0x01, t[(r+)%])
                         ^ FFmul(0x01, t[(r+)%]);
         }
     }
 }

 void AES::AddRoundKey(unsigned char state[][], unsigned char k[][])
 {
     int r,c;
     for(c=; c<; c++)
     {
         for(r=; r<; r++)
         {
             state[r][c] ^= k[r][c];
         }
     }
 }

 void AES::InvSubBytes(unsigned char state[][])
 {
     int r,c;
     for(r=; r<; r++)
     {
         for(c=; c<; c++)
         {
             state[r][c] = InvSbox[state[r][c]];
         }
     }
 }

 void AES::InvShiftRows(unsigned char state[][])
 {
     unsigned char t[];
     int r,c;
     for(r=; r<; r++)
     {
         for(c=; c<; c++)
         {
             t[c] = state[r][(c-r+)%];
         }
         for(c=; c<; c++)
         {
             state[r][c] = t[c];
         }
     }
 }

 void AES::InvMixColumns(unsigned char state[][])
 {
     unsigned char t[];
     int r,c;
     for(c=; c< ; c++)
     {
         for(r=; r<; r++)
         {
             t[r] = state[r][c];
         }
         for(r=; r<; r++)
         {
             state[r][c] = FFmul(0x0e, t[r])
                         ^ FFmul(0x0b, t[(r+)%])
                         ^ FFmul(0x0d, t[(r+)%])
                         ^ FFmul(0x09, t[(r+)%]);
         }
     }
 }

　　上面的加密算法是没问题的，但是接口有两个需要注意的地方，也就是在头文件中备注的地方：

1、数组的大小必须是16字节或者16的整数倍。

2、不能直接使用字符串输出，因为加密后的数组内容可能有'\0'，字符串会被截断。

　　为了更方便的使用此加密算法，我封装了一个接口类，声明如下：

（3）aes_encryptor.h

#ifndef SRC_UTILS_AES_ENCRYPTOR_H
#define SRC_UTILS_AES_ENCRYPTOR_H

#include <string>

class AES;

class AesEncryptor
{
public:
    AesEncryptor(unsigned char* key);
    ~AesEncryptor(void);

    std::string EncryptString(std::string strInfor);
    std::string DecryptString(std::string strMessage);

    void EncryptTxtFile(const char* inputFileName, const char* outputFileName);
    void DecryptTxtFile(const char* inputFileName, const char* outputFileName);

private:
    void Byte2Hex(const unsigned char* src, int len, char* dest);
    void Hex2Byte(const char* src, int len, unsigned char* dest);
    int  Char2Int(char c);

private:
    AES* m_pEncryptor;
};

#endif        // SRC_UTILS_AES_ENCRYPTOR_H

（4）aes_encryptor.cpp

 #include "aes.h"
 #include "aes_encryptor.h"
 #include "log.h"

 #include <fstream>
 using namespace std;

 AesEncryptor::AesEncryptor(unsigned char* key)
 {
     m_pEncryptor = new AES(key);
 }

 AesEncryptor::~AesEncryptor(void)
 {
     delete m_pEncryptor;
 }

 void AesEncryptor::Byte2Hex(const unsigned char* src, int len, char* dest) {
     for (int i=; i<len; ++i) {
         sprintf_s(dest + i * , , "%02X", src[i]);
     }
 }

 void AesEncryptor::Hex2Byte(const char* src, int len, unsigned char* dest) {
     int length = len / ;
     for (int i=; i<length; ++i) {
         dest[i] = Char2Int(src[i * ]) *  + Char2Int(src[i *  + ]);
     }
 }

 int AesEncryptor::Char2Int(char c) {
     if ('' <= c && c <= '') {
         return (c - '');
     }
     else if ('a' <= c && c<= 'f') {
         return (c - 'a' + );
     }
     else if ('A' <= c && c<= 'F') {
         return (c - 'A' + );
     }
     return -;
 }

 string AesEncryptor::EncryptString(string strInfor) {
     int nLength = strInfor.length();
     int spaceLength =  - (nLength % );
     unsigned char* pBuffer = new unsigned char[nLength + spaceLength];
     memset(pBuffer, '\0', nLength + spaceLength);
     memcpy_s(pBuffer, nLength + spaceLength, strInfor.c_str(), nLength);
     m_pEncryptor->Cipher(pBuffer, nLength + spaceLength);

     // 这里需要把得到的字符数组转换成十六进制字符串
     char* pOut = new char[ * (nLength + spaceLength)];
     memset(pOut, '\0',  * (nLength + spaceLength));
     Byte2Hex(pBuffer, nLength + spaceLength, pOut);

     string retValue(pOut);
     delete[] pBuffer;
     delete[] pOut;
     return retValue;
 }

 string AesEncryptor::DecryptString(string strMessage) {
     int nLength = strMessage.length() / ;
     unsigned char* pBuffer = new unsigned char[nLength];
     memset(pBuffer, '\0', nLength);
     Hex2Byte(strMessage.c_str(), strMessage.length(), pBuffer);

     m_pEncryptor->InvCipher(pBuffer, nLength);
     string retValue((char*)pBuffer);
     delete[] pBuffer;
     return retValue;
 }

 void AesEncryptor::EncryptTxtFile(const char* inputFileName, const char* outputFileName) {
     ifstream ifs;

     // Open file:
     ifs.open(inputFileName);
     if (!ifs) {
         UNILOGW("AesEncryptor::EncryptTxtFile() - Open input file failed!");
         return ;
     }

     // Read config data:
     string strInfor;
     string strLine;
     while (!ifs.eof()) {
         char temp[];
         memset(temp, '\0', );
         ifs.read(temp, );
         strInfor += temp;
     }
     ifs.close();

     // Encrypt
     strLine = EncryptString(strInfor);

     // Writefile
     ofstream ofs;
     ofs.open(outputFileName);
     if (!ofs) {
         UNILOGW("AesEncryptor::EncryptTxtFile() - Open output file failed!");
         return ;
     }
     ofs << strLine;
     ofs.close();
 }

 void AesEncryptor::DecryptTxtFile(const char* inputFile, const char* outputFile) {
     ifstream ifs;

     // Open file:
     ifs.open(inputFile);
     if (!ifs) {
         UNILOGW("AesEncryptor::DecryptTxtFile() - Open input file failed!");
         return ;
     }

     // Read config data:
     string strInfor;
     string strLine;
     while (!ifs.eof()) {
         char temp[];
         memset(temp, '\0', );
         ifs.read(temp, );
         strInfor += temp;
     }
     ifs.close();

     // Encrypt
     strLine = DecryptString(strInfor);

     // Writefile
     ofstream ofs;
     ofs.open(outputFile);
     if (!ofs) {
         UNILOGW("AesEncryptor::DecryptTxtFile() - Open output file failed!");
         return ;
     }
     ofs << strLine;
     ofs.close();
 }

　　从代码中可以看到增加了以下特性：

1、支持对std::string 字符串类型的加密，并返回相应的字符串，这个字符串是将加密后的内容转换成十六进制表示的，所以不存在截断的问题。当然了，解密的时候也需要转换成真正的unsigned char数组；

2、支持直接对文本文件进行加密，指定输入和输出的文件名即可。

PS: 多说一句，从网上看别人封装的代码时，先看评论和反应，有的时候网友写个带漏洞的程序坑死人不负责的。