用c++实现了md5算法。包含 md5.h 和md5.cpp 两个文件。
主要参考百度百科 “MD5” 原理的描述：http://baike.baidu.cn/view/7636.htm，代码中变量命名也是参考其中的公式，程序的使用说明在md5.h 文件的末尾注释中。
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
md5.cpp
#include"md5.h"
#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';
md5Result_[0] = '\0';
totalInputBits_ = 0;
isDone_ = false;
}
MD5::MD5()
{
init();
}
inline MD5::uint32 MD5::RotateLeft(const uint32 x, int n)
{
return (x << n) | (x >> (32-n));
// if x is signed, use: (x << n) | ((x & 0xFFFFFFFF) >> (32-n))
}
inline MD5::uint32 MD5::F(const uint32 x, const uint32 y, const uint32 z)
{
return (x & y) | ((~x) & z);
}
inline MD5::uint32 MD5::G(const uint32 x, const uint32 y, const uint32 z)
{
return (x & z) | (y & (~z));
}
inline MD5::uint32 MD5::H(const uint32 x, const uint32 y, const uint32 z)
{
return x ^ y ^ z;
}
inline MD5::uint32 MD5::I(const uint32 x, const uint32 y, const uint32 z)
{
return y ^ (x | (~z));
}
inline void MD5::FF(uint32 &a, const uint32 b, const uint32 c, const uint32 d,
const uint32 Mj, const int s, const uint32 ti)
{
a = b + RotateLeft(a + F(b, c, d) + Mj + ti, s);
}
inline void MD5::GG(uint32 &a, const uint32 b, const uint32 c, const uint32 d,
const uint32 Mj, const int s, const uint32 ti)
{
a = b + RotateLeft(a + G(b, c, d) + Mj + ti, s);
}
inline void MD5::HH(uint32 &a, const uint32 b, const uint32 c, const uint32 d,
const uint32 Mj, const int s, const uint32 ti)
{
a = b + RotateLeft(a + H(b, c, d) + Mj + ti, s);
}
inline void MD5::II(uint32 &a, const uint32 b, const uint32 c, const uint32 d,
const uint32 Mj, const int s, const uint32 ti)
{
a = b + RotateLeft(a + I(b, c, d) + Mj + ti, s);
}
// link A B C D to result(bit style result and hexadecimal style result)
void MD5::LinkResult()
{
//bit style result
for(int i = 0; i < 4; i++) //link A: low to high
{
md5Result_[i] = (A >> 8*i) & 0xff;
}
for(int i = 4; i<8; i++) //link B: low to high
{
md5Result_[i] = (B >> 8*(i - 4)) & 0xff;
}
for(int i = 8; i<12; i++) //link C: low to high
{
md5Result_[i] = (C >> 8*(i - 8)) & 0xff;
}
for(int i = 12; i<16; i++) //link D: low to high
{
md5Result_[i] = (D >> 8*(i - 12)) & 0xff;
}
//change to hexadecimal style result
// note: it is not the same as simply link hex(A) hex(B) hex(C) hex(D)
for(int i = 0; i < 16; i++)
sprintf(& md5Result_hex_[i*2], "%02x", md5Result_[i]);
md5Result_hex_[32] = '\0';
}
//print the md5 by hex
void MD5::printMd5()
{
if(!isDone_)
{
cout<< "Error: computation is not finished" <<endl;
}
else
cout<< "MD5 Value: " << md5Result_hex_ <<endl;
}
//get the md5 value of hex style
string MD5::GetMd5()
{
if(!isDone_)
{
cout<< "Error: computation is not finished" <<endl;
exit(0);
}
string a((const char *)md5Result_hex_);
return a;
}
void MD5::UcharToUint(uint32 output[], const uchar8 input[], const unsigned int transLength)
{
for(int i = 0, j = 0; j < transLength; i++, j += 4)
{
output[i] = ((uint32)input[j]) | (((uint32)input[j+1]) << 8) |
(((uint32)input[j+2]) << 16) | (((uint32)input[j+3]) << 24);
}
}
// four round on a block of 512 bits;
void MD5::FourRound(const uchar8 block[])
{
uint32 a = A, b = B, c = C, d = D;
uint32 M[16];
UcharToUint(M, block, blockLen_); //blockLen_ is a const int =64;
//round 1
FF (a, b, c, d, M[ 0], S[0][0], 0xd76aa478);
FF (d, a, b, c, M[ 1], S[0][1], 0xe8c7b756);
FF (c, d, a, b, M[ 2], S[0][2], 0x242070db);
FF (b, c, d, a, M[ 3], S[0][3], 0xc1bdceee);
FF (a, b, c, d, M[ 4], S[0][0], 0xf57c0faf);
FF (d, a, b, c, M[ 5], S[0][1], 0x4787c62a);
FF (c, d, a, b, M[ 6], S[0][2], 0xa8304613);
FF (b, c, d, a, M[ 7], S[0][3], 0xfd469501);
FF (a, b, c, d, M[ 8], S[0][0], 0x698098d8);
FF (d, a, b, c, M[ 9], S[0][1], 0x8b44f7af);
FF (c, d, a, b, M[10], S[0][2], 0xffff5bb1);
FF (b, c, d, a, M[11], S[0][3], 0x895cd7be);
FF (a, b, c, d, M[12], S[0][0], 0x6b901122);
FF (d, a, b, c, M[13], S[0][1], 0xfd987193);
FF (c, d, a, b, M[14], S[0][2], 0xa679438e);
FF (b, c, d, a, M[15], S[0][3], 0x49b40821);
// round 2
GG (a, b, c, d, M[ 1], S[1][0], 0xf61e2562);
GG (d, a, b, c, M[ 6], S[1][1], 0xc040b340);
GG (c, d, a, b, M[11], S[1][2], 0x265e5a51);
GG (b, c, d, a, M[ 0], S[1][3], 0xe9b6c7aa);
GG (a, b, c, d, M[ 5], S[1][0], 0xd62f105d);
GG (d, a, b, c, M[10], S[1][1], 0x2441453);
GG (c, d, a, b, M[15], S[1][2], 0xd8a1e681);
GG (b, c, d, a, M[ 4], S[1][3], 0xe7d3fbc8);
GG (a, b, c, d, M[ 9], S[1][0], 0x21e1cde6);
GG (d, a, b, c, M[14], S[1][1], 0xc33707d6);
GG (c, d, a, b, M[ 3], S[1][2], 0xf4d50d87);
GG (b, c, d, a, M[ 8], S[1][3], 0x455a14ed);
GG (a, b, c, d, M[13], S[1][0], 0xa9e3e905);
GG (d, a, b, c, M[ 2], S[1][1], 0xfcefa3f8);
GG (c, d, a, b, M[ 7], S[1][2], 0x676f02d9);
GG (b, c, d, a, M[12], S[1][3], 0x8d2a4c8a);
//round 3
HH (a, b, c, d, M[ 5], S[2][0], 0xfffa3942);
HH (d, a, b, c, M[ 8], S[2][1], 0x8771f681);
HH (c, d, a, b, M[11], S[2][2], 0x6d9d6122);
HH (b, c, d, a, M[14], S[2][3], 0xfde5380c);
HH (a, b, c, d, M[ 1], S[2][0], 0xa4beea44);
HH (d, a, b, c, M[ 4], S[2][1], 0x4bdecfa9);
HH (c, d, a, b, M[ 7], S[2][2], 0xf6bb4b60);
HH (b, c, d, a, M[10], S[2][3], 0xbebfbc70);
HH (a, b, c, d, M[13], S[2][0], 0x289b7ec6);
HH (d, a, b, c, M[ 0], S[2][1], 0xeaa127fa);
HH (c, d, a, b, M[ 3], S[2][2], 0xd4ef3085);
HH (b, c, d, a, M[ 6], S[2][3], 0x4881d05);
HH (a, b, c, d, M[ 9], S[2][0], 0xd9d4d039);
HH (d, a, b, c, M[12], S[2][1], 0xe6db99e5);
HH (c, d, a, b, M[15], S[2][2], 0x1fa27cf8);
HH (b, c, d, a, M[ 2], S[2][3], 0xc4ac5665);
//round 4
II (a, b, c, d, M[ 0], S[3][0], 0xf4292244);
II (d, a, b, c, M[ 7], S[3][1], 0x432aff97);
II (c, d, a, b, M[14], S[3][2], 0xab9423a7);
II (b, c, d, a, M[ 5], S[3][3], 0xfc93a039);
II (a, b, c, d, M[12], S[3][0], 0x655b59c3);
II (d, a, b, c, M[ 3], S[3][1], 0x8f0ccc92);
II (c, d, a, b, M[10], S[3][2], 0xffeff47d);
II (b, c, d, a, M[ 1], S[3][3], 0x85845dd1);
II (a, b, c, d, M[ 8], S[3][0], 0x6fa87e4f);
II (d, a, b, c, M[15], S[3][1], 0xfe2ce6e0);
II (c, d, a, b, M[ 6], S[3][2], 0xa3014314);
II (b, c, d, a, M[13], S[3][3], 0x4e0811a1);
II (a, b, c, d, M[ 4], S[3][0], 0xf7537e82);
II (d, a, b, c, M[11], S[3][1], 0xbd3af235);
II (c, d, a, b, M[ 2], S[3][2], 0x2ad7d2bb);
II (b, c, d, a, M[ 9], S[3][3], 0xeb86d391);
A += a;
B += b;
C += c;
D += d;
}
// update md5,must consider the remain_.
void MD5::UpdateMd5(const uchar8 input[], const int length)
{
isDone_ = false;
totalInputBits_ += (length << 3);
int start = blockLen_ - remainNum_; //blockLen_ = 64
//copy a part of input to remain_ so it can form a block(size=64)
if(start <= length)
{
// can form a block,then do FourRound to this block
memcpy(&remain_[remainNum_], input, start) ;
FourRound(remain_);
int i;
for(i = start; i <= length - blockLen_; i += blockLen_)
{
FourRound(&input[i]);
}
remainNum_ = length - i;
memcpy(remain_, &input[i], remainNum_);
}
else
{
// can not form a block, function return;
memcpy(&remain_[remainNum_], input, length);
remainNum_ += length;
}
}
void MD5::UpdateMd5(const char8 input[], const int length)
{
UpdateMd5((const uchar8 *)input, length);
}
// padding with 100000... to remain_ and add the 64bit original size of input
void MD5::Finalize()
{
if(isDone_ == true)
return;
uchar8 padding[64] = {
0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};
int temp = 56 - remainNum_; //56 = 448/8
if(temp > 0)
{
UpdateMd5(padding, temp);
totalInputBits_ -= (temp << 3);
}
else if(temp < 0)
{
UpdateMd5(padding, 64 + temp);
totalInputBits_ -= ((64 + temp) << 3);
}
// trans totalInputBits_ to uchar8 (64bits)
uchar8 Bits[8];
for(int i = 0; i < 8; i++)
{
Bits[i] = (totalInputBits_ >> 8*i) & 0xff;
}
UpdateMd5(Bits, 8); // add the number of original input (the last 64bits)
LinkResult();
isDone_ = true;
}
// comput the md5 based on input, (just this one input)
void MD5::ComputMd5(const uchar8 input[], const int length)
{
init();
UpdateMd5(input, length);
Finalize();
}
void MD5::ComputMd5(const char8 input[], const int length)
{
ComputMd5((const uchar8 *)input, length);
}