c++实现MD5算法实现代码

测试结果和百度百科测试例子一致。

实现过程中需要注意事项：最后把四个变量A B C D 链接成结果时 ，注意变量高低位的先后顺序，具体参考 LinkResult（）方法。

md5.h

#include <iostream>
#include <string>
using namespace std;

class MD5
{
    public:
        typedef unsigned char uchar8; //make sure it is 8bit
        typedef char char8; //make sure it is 8bit
        MD5();

        void init();

        void UpdateMd5(const uchar8 input[], const int length);     
        void UpdateMd5(const char8 input[], const int length);    

        void Finalize();

        void ComputMd5(const uchar8 input[], const int length);
        void ComputMd5(const char8 input[], const int length);

        string GetMd5();

        void printMd5();

       
    private:
        typedef unsigned int uint32;       //make sure it is 32 bit;
        typedef unsigned long long uint64; //make sure it is 64 bit;
        uint32 A, B, C, D;
        const static int blockLen_ = 64;    // 512/8                                 
        //the remain after last updata (because md5 may be computed segment by segment)
        uchar8 remain_[blockLen_];                   
        int remainNum_ ;         // the number of remain_,  < 64
        uint64 totalInputBits_;
        uchar8 md5Result_[16];   //bit style md5 result,totally 128 bit
        char md5Result_hex_[33]; //hexadecimal style result; md5Result_hex_[32]='\0'
        bool isDone_;            // indicate the comput is finished;

        inline uint32 RotateLeft(const uint32 x, int n);
        inline uint32 F(const uint32 x, const uint32 y, const uint32 z);
        inline uint32 G(const uint32 x, const uint32 y, const uint32 z);
        inline uint32 H(const uint32 x, const uint32 y, const uint32 z);
        inline uint32 I(const uint32 x, const uint32 y, const uint32 z);
        inline void FF(uint32 &a, const uint32 b, const uint32 c, const uint32 d,
                       const uint32 Mj, const int s, const uint32 ti);
        inline void GG(uint32 &a, const uint32 b, const uint32 c, const uint32 d,
                       const uint32 Mj, const int s, const uint32 ti);
        inline void HH(uint32 &a, const uint32 b, const uint32 c, const uint32 d,
                       const uint32 Mj, const int s, const uint32 ti);
        inline void II(uint32 &a, const uint32 b, const uint32 c, const uint32 d,
                       const uint32 Mj, const int s, const uint32 ti);
                      

        void UcharToUint(uint32 output[], const uchar8 input[], const unsigned int transLength);

        void FourRound(const uchar8 block[]);   

        void LinkResult();

};

/* user guide
   you can comput the md5 by using the funtion ComputMd5
   eg:
       MD5 m;
       MD5::char8 str[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
       m.ComputMd5(str,sizeof(str) - 1);  
       m.printMd5();

    if you want to comput segment by segment,you can do as follow, and init() is suggested
    the begging,and Finalize() must call in the end:

        MD5 M;
        m.init();
        MD5::uchar8 str1[] = "ABCDEFGHIJKLMN";
        MD5::uchar8 str2[] = "OPQRSTUVWXYZabcdefghijk";
        MD5::uchar8 str3[] = "lmnopqrstuvwxyz";
        m.UpdateMd5(str1,sizeof(str1) - 1);
        m.UpdateMd5(str2,sizeof(str2) - 1);
        m.UpdateMd5(str3,sizeof(str3) - 1);
        m.Finalize();
        m.printMd5();

    if you want to comput the md5 of a file, you can use the interface of this program.
*/

#endif
</div>

md5.cpp

#include<iostream>
using namespace std;

const int S[4][4] = {7, 12, 17, 22,
                     5, 9, 14, 20,
                     4, 11, 16, 23,
                     6, 10, 15, 21};
void MD5::init()
{
    A = 0x67452301;
    B = 0xefcdab89;
    C = 0x98badcfe;
    D = 0x10325476;
    remainNum_ = 0;
    remain_[0] = '\0';
    md5Result_hex_[0] = '\0';
 &nb