- Message Digest Algorithm 5(消息摘要算法第五版),对任意长度输入能产生128bit散列值。理论上来说,结果只有2^128种而原文有无数种,因此会存在碰撞,所以有可能两个原文对应相同的散列值,不过找出这样的原文很困难
计算过程
- 填充消息使其位长mod512为448,填充方法是加一个1和n个0,至少填充1位,至多填充512位,填充后消息长度为
512N+448bit
- 在第一步后填充64位消息长度,如果填充前消息长度大于2^64则只使用低64位,填充后消息长度为
512(N+1)bit
- 用四个幻数ABCD(十六进制的整数)计算消息摘要,ABCD分别是一个32位寄存器
// 物理顺序
A = 01234567h
B = 89abcdefh
C = fedcba98h
D = 76543210h
// 代码中定义
A = 0x67452301;
B = 0xefcdab89;
C = 0x98badcfe;
D = 0x10325476;
- 每512bit分为一组,再将512bit分为16个64bit(8字节)小组
- 将ABCD副本abcd中的三个经过FGHI运算后与第四个相加,再加上32位字和一个32位字的加法常数,将结果循环左移若干位后再加上abcd之一,最后回送到ABCD完成一次循环
F(X,Y,Z) = (X&Y)|((~X)&Z)
G(X,Y,Z) = (X&Z)|(Y&(~Z))
H(X,Y,Z) = X^Y^Z
I(X,Y,Z) = Y^(X|(~Z))
- Mj表示消息的第j个分组(0到15,共16个分组)
FF(a,b,c,d,Mj,s,ti)表示a=b+((a+F(b,c,d)+Mj+ti)<<<s)
GG(a,b,c,d,Mj,s,ti)表示a=b+((a+G(b,c,d)+Mj+ti)<<<s)
HH(a,b,c,d,Mj,s,ti)表示a=b+((a+H(b,c,d)+Mj+ti)<<<s)
II(a,b,c,d,Mj,s,ti)表示a=b+((a+I(b,c,d)+Mj+ti)<<<s)
// 1
a=FF(a,b,c,d,M0,7,0xd76aa478)
b=FF(d,a,b,c,M1,12,0xe8c7b756)
c=FF(c,d,a,b,M2,17,0x242070db)
d=FF(b,c,d,a,M3,22,0xc1bdceee)
a=FF(a,b,c,d,M4,7,0xf57c0faf)
b=FF(d,a,b,c,M5,12,0x4787c62a)
c=FF(c,d,a,b,M6,17,0xa8304613)
d=FF(b,c,d,a,M7,22,0xfd469501)
a=FF(a,b,c,d,M8,7,0x698098d8)
b=FF(d,a,b,c,M9,12,0x8b44f7af)
c=FF(c,d,a,b,M10,17,0xffff5bb1)
d=FF(b,c,d,a,M11,22,0x895cd7be)
a=FF(a,b,c,d,M12,7,0x6b901122)
b=FF(d,a,b,c,M13,12,0xfd987193)
c=FF(c,d,a,b,M14,17,0xa679438e)
d=FF(b,c,d,a,M15,22,0x49b40821)
// 2
a=GG(a,b,c,d,M1,5,0xf61e2562)
b=GG(d,a,b,c,M6,9,0xc040b340)
c=GG(c,d,a,b,M11,14,0x265e5a51)
d=GG(b,c,d,a,M0,20,0xe9b6c7aa)
a=GG(a,b,c,d,M5,5,0xd62f105d)
b=GG(d,a,b,c,M10,9,0x02441453)
c=GG(c,d,a,b,M15,14,0xd8a1e681)
d=GG(b,c,d,a,M4,20,0xe7d3fbc8)
a=GG(a,b,c,d,M9,5,0x21e1cde6)
b=GG(d,a,b,c,M14,9,0xc33707d6)
c=GG(c,d,a,b,M3,14,0xf4d50d87)
d=GG(b,c,d,a,M8,20,0x455a14ed)
a=GG(a,b,c,d,M13,5,0xa9e3e905)
b=GG(d,a,b,c,M2,9,0xfcefa3f8)
c=GG(c,d,a,b,M7,14,0x676f02d9)
d=GG(b,c,d,a,M12,20,0x8d2a4c8a)
// 3
a=HH(a,b,c,d,M5,4,0xfffa3942)
b=HH(d,a,b,c,M8,11,0x8771f681)
c=HH(c,d,a,b,M11,16,0x6d9d6122)
d=HH(b,c,d,a,M14,23,0xfde5380c)
a=HH(a,b,c,d,M1,4,0xa4beea44)
b=HH(d,a,b,c,M4,11,0x4bdecfa9)
c=HH(c,d,a,b,M7,16,0xf6bb4b60)
d=HH(b,c,d,a,M10,23,0xbebfbc70)
a=HH(a,b,c,d,M13,4,0x289b7ec6)
b=HH(d,a,b,c,M0,11,0xeaa127fa)
c=HH(c,d,a,b,M3,16,0xd4ef3085)
d=HH(b,c,d,a,M6,23,0x04881d05)
a=HH(a,b,c,d,M9,4,0xd9d4d039)
b=HH(d,a,b,c,M12,11,0xe6db99e5)
c=HH(c,d,a,b,M15,16,0x1fa27cf8)
d=HH(b,c,d,a,M2,23,0xc4ac5665)
// 4
a=II(a,b,c,d,M0,6,0xf4292244)
b=II(d,a,b,c,M7,10,0x432aff97)
c=II(c,d,a,b,M14,15,0xab9423a7)
d=II(b,c,d,a,M5,21,0xfc93a039)
a=II(a,b,c,d,M12,6,0x655b59c3)
b=II(d,a,b,c,M3,10,0x8f0ccc92)
c=II(c,d,a,b,M10,15,0xffeff47d)
d=II(b,c,d,a,M1,21,0x85845dd1)
a=II(a,b,c,d,M8,6,0x6fa87e4f)
b=II(d,a,b,c,M15,10,0xfe2ce6e0)
c=II(c,d,a,b,M6,15,0xa3014314)
d=II(b,c,d,a,M13,21,0x4e0811a1)
a=II(a,b,c,d,M4,6,0xf7537e82)
b=II(d,a,b,c,M11,10,0xbd3af235)
c=II(c,d,a,b,M2,15,0x2ad7d2bb)
d=II(b,c,d,a,M9,21,0xeb86d391)
- 加法常数由一张表T[i]定义,i为1到64之中的值,T[i]等于4294967296*abs(sin i)结果的整数部分,4294967296为2^32,i用弧度表示
- 所有512bit的分组都运算完后,ABCD连接起来就是最终结果
实现
/*
*******************************************************
* brief: md5 encryption
* author: Monkey.Knight
*******************************************************
*/
#ifndef __MD5_ENCODE_H__
#define __MD5_ENCODE_H__
// std
#include <string>
// define
#define UInt32 unsigned int
#define BIT_OF_BYTE 8
#define BIT_OF_GROUP 512
#define SRC_DATA_LEN 64
// 四个非线性函数宏定义
#define DEF_F(X, Y, Z ) ((( (X) & (Y) )|((~X)&(Z))))
#define DEF_G(X, Y, Z) (((X)&(Z))|((Y)&(~Z)))
#define DEF_H(X, Y, Z) ((X)^(Y)^(Z))
#define DEF_I(X, Y, Z) ((Y)^((X)|(~Z)))
// 求链接数函数宏定义
#define FF(a, b, c, d, Mj, s, ti) (a = b + CycleMoveLeft((a + DEF_F(b,c,d) + Mj + ti),s));
#define GG(a, b, c, d, Mj, s, ti) (a = b + CycleMoveLeft((a + DEF_G(b,c,d) + Mj + ti),s));
#define HH(a, b, c, d, Mj, s, ti) (a = b + CycleMoveLeft((a + DEF_H(b,c,d) + Mj + ti),s));
#define II(a, b, c, d, Mj, s, ti) (a = b + CycleMoveLeft((a + DEF_I(b,c,d) + Mj + ti),s));
class Md5Encode {
public:
// 4轮循环算法
struct ParamDynamic{
UInt32 ua_;
UInt32 ub_;
UInt32 uc_;
UInt32 ud_;
UInt32 va_last_;
UInt32 vb_last_;
UInt32 vc_last_;
UInt32 vd_last_;
};
public:
Md5Encode() {
}
std::string Encode(std::string src_info);
protected:
UInt32 CycleMoveLeft(UInt32 src_num, int bit_num_to_move);
UInt32 FillData(const char *in_data_ptr, int data_byte_len, char** out_data_ptr);
void RoundF(char *data_512_ptr, ParamDynamic & param);
void RoundG(char *data_512_ptr, ParamDynamic & param);
void RoundH(char *data_512_ptr, ParamDynamic & param);
void RoundI(char *data_512_ptr, ParamDynamic & param);
void RotationCalculate(char *data_512_ptr, ParamDynamic & param);
std::string GetHexStr(unsigned int num_str);
private:
// 幻数定义
static const int kA;
static const int kB;
static const int kC;
static const int kD;
static const unsigned long long k_ti_num_integer;
};
#endif
#include "md5_encode.h"
#include <iostream>
#include <cmath>
#include <cstring>
using namespace std;
// 幻数定义
const int Md5Encode::kA = 0x67452301;
const int Md5Encode::kB = 0xefcdab89;
const int Md5Encode::kC = 0x98badcfe;
const int Md5Encode::kD = 0x10325476;
const unsigned long long Md5Encode::k_ti_num_integer = 4294967296;
// function: CycleMoveLeft
// @param src_num:要左移的数
// @param bit_num_to_move:要移动的bit位数
// @return 循环左移后的结果数
UInt32 Md5Encode::CycleMoveLeft(UInt32 src_num, int bit_num_to_move) {
UInt32 src_num1 = src_num;
UInt32 src_num2 = src_num;
if (0 >= bit_num_to_move) {
return src_num;
}
UInt32 num1 = src_num1 << bit_num_to_move;
UInt32 num2 = src_num2 >> (32 - bit_num_to_move);
return ((src_num1 << bit_num_to_move) \
| (src_num2 >> (32 - bit_num_to_move)));
}
// function: FillData
// @param in_data_ptr: 要加密的信息数据
// @param data_byte_len: 数据的字节数
// @param out_data_ptr: 填充必要信息后的数据
// return : 填充信息后的数据长度,以字节为单位
UInt32 Md5Encode::FillData(const char *in_data_ptr, int data_byte_len, char** out_data_ptr) {
int bit_num = data_byte_len*BIT_OF_BYTE;
int grop_num = bit_num / BIT_OF_GROUP;
int mod_bit_num = bit_num % BIT_OF_GROUP;
int bit_need_fill = 0;
if (mod_bit_num > (BIT_OF_GROUP - SRC_DATA_LEN)) {
bit_need_fill = (BIT_OF_GROUP - mod_bit_num);
bit_need_fill += (BIT_OF_GROUP - SRC_DATA_LEN);
}
else {
bit_need_fill = (BIT_OF_GROUP - SRC_DATA_LEN) - mod_bit_num; // 这里多加了一个BIT_OF_GROUP,避免bit_need_fill正好等于0,暂时不加
}
int all_bit = bit_num + bit_need_fill;
if (0 < bit_need_fill) {
*out_data_ptr = new char[all_bit / BIT_OF_BYTE + SRC_DATA_LEN / BIT_OF_BYTE];
memset(*out_data_ptr, 0, all_bit / BIT_OF_BYTE + SRC_DATA_LEN / BIT_OF_BYTE);
// copy data
memcpy(*out_data_ptr, in_data_ptr, data_byte_len);
// fill rest data
unsigned char *tmp = reinterpret_cast<unsigned char *>(*out_data_ptr);
tmp += data_byte_len;
// fill 1 and 0
*tmp = 0x80;
// fill origin data len
unsigned long long * origin_num = (unsigned long long *)((*out_data_ptr) + ((all_bit / BIT_OF_BYTE)));
*origin_num = data_byte_len*BIT_OF_BYTE;
}
return (all_bit / BIT_OF_BYTE + SRC_DATA_LEN / BIT_OF_BYTE);
}
void Md5Encode::RoundF(char *data_BIT_OF_GROUP_ptr, ParamDynamic & param) {
UInt32 *M = reinterpret_cast<UInt32*>(data_BIT_OF_GROUP_ptr);
int s[] = { 7, 12, 17, 22 };
for (int i = 0; i < 16; ++i) {
UInt32 ti = k_ti_num_integer * abs(sin(i + 1));
if (i % 4 == 0) {
FF(param.ua_, param.ub_, param.uc_, param.ud_, M[i], s[i % 4], ti);
}
else if (i % 4 == 1) {
FF(param.ud_, param.ua_, param.ub_, param.uc_, M[i], s[i % 4], ti);
}
else if (i % 4 == 2) {
FF(param.uc_, param.ud_, param.ua_, param.ub_, M[i], s[i % 4], ti);
}
else if (i % 4 == 3) {
FF(param.ub_, param.uc_, param.ud_, param.ua_, M[i], s[i % 4], ti);
}
}
}
void Md5Encode::RoundG(char *data_BIT_OF_GROUP_ptr, ParamDynamic & param) {
UInt32 *M = reinterpret_cast<UInt32*>(data_BIT_OF_GROUP_ptr);
int s[] = { 5, 9, 14, 20 };
for (int i = 0; i < 16; ++i) {
UInt32 ti = k_ti_num_integer * abs(sin(i + 1 + 16));
int index = (i * 5 + 1) % 16;
if (i % 4 == 0) {
GG(param.ua_, param.ub_, param.uc_, param.ud_, M[index], s[i % 4], ti);
}
else if (i % 4 == 1) {
GG(param.ud_, param.ua_, param.ub_, param.uc_, M[index], s[i % 4], ti);
}
else if (i % 4 == 2) {
GG(param.uc_, param.ud_, param.ua_, param.ub_, M[index], s[i % 4], ti);
}
else if (i % 4 == 3) {
GG(param.ub_, param.uc_, param.ud_, param.ua_, M[index], s[i % 4], ti);
}
}
}
void Md5Encode::RoundH(char *data_BIT_OF_GROUP_ptr, ParamDynamic & param) {
UInt32 *M = reinterpret_cast<UInt32*>(data_BIT_OF_GROUP_ptr);
int s[] = { 4, 11, 16, 23 };
for (int i = 0; i < 16; ++i) {
UInt32 ti = k_ti_num_integer * abs(sin(i + 1 + 32));
int index = (i * 3 + 5) % 16;
if (i % 4 == 0) {
HH(param.ua_, param.ub_, param.uc_, param.ud_, M[index], s[i % 4], ti);
}
else if (i % 4 == 1) {
HH(param.ud_, param.ua_, param.ub_, param.uc_, M[index], s[i % 4], ti);
}
else if (i % 4 == 2) {
HH(param.uc_, param.ud_, param.ua_, param.ub_, M[index], s[i % 4], ti);
}
else if (i % 4 == 3) {
HH(param.ub_, param.uc_, param.ud_, param.ua_, M[index], s[i % 4], ti);
}
}
}
void Md5Encode::RoundI(char *data_BIT_OF_GROUP_ptr, ParamDynamic & param) {
UInt32 *M = reinterpret_cast<UInt32*>(data_BIT_OF_GROUP_ptr);
int s[] = { 6, 10, 15, 21 };
for (int i = 0; i < 16; ++i) {
UInt32 ti = k_ti_num_integer * abs(sin(i + 1 + 48));
int index = (i * 7 + 0) % 16;
if (i % 4 == 0) {
II(param.ua_, param.ub_, param.uc_, param.ud_, M[index], s[i % 4], ti);
}
else if (i % 4 == 1) {
II(param.ud_, param.ua_, param.ub_, param.uc_, M[index], s[i % 4], ti);
}
else if (i % 4 == 2) {
II(param.uc_, param.ud_, param.ua_, param.ub_, M[index], s[i % 4], ti);
}
else if (i % 4 == 3) {
II(param.ub_, param.uc_, param.ud_, param.ua_, M[index], s[i % 4], ti);
}
}
}
void Md5Encode::RotationCalculate(char *data_512_ptr, ParamDynamic & param) {
if (NULL == data_512_ptr) {
return;
}
RoundF(data_512_ptr, param);
RoundG(data_512_ptr, param);
RoundH(data_512_ptr, param);
RoundI(data_512_ptr, param);
param.ua_ = param.va_last_ + param.ua_;
param.ub_ = param.vb_last_ + param.ub_;
param.uc_ = param.vc_last_ + param.uc_;
param.ud_ = param.vd_last_ + param.ud_;
param.va_last_ = param.ua_;
param.vb_last_ = param.ub_;
param.vc_last_ = param.uc_;
param.vd_last_ = param.ud_;
}
// 转换成十六进制字符串输出
std::string Md5Encode::GetHexStr(unsigned int num_str) {
std::string hexstr = "";
char szch[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
unsigned char *tmptr = (unsigned char *)&num_str;
int len = sizeof(num_str);
// 小端字节序,逆序打印
for (int i = 0; i < len; i++){
unsigned char ch = tmptr[i] & 0xF0;
ch = ch >> 4;
hexstr.append(1, szch[ch]);
ch = tmptr[i] & 0x0F;
hexstr.append(1, szch[ch]);
}
return hexstr;
}
// function: Encode
// @param src_info:要加密的信息
// return :加密后的MD5值
std::string Md5Encode::Encode(std::string src_info) {
ParamDynamic param;
param.ua_ = kA;
param.ub_ = kB;
param.uc_ = kC;
param.ud_ = kD;
param.va_last_ = kA;
param.vb_last_ = kB;
param.vc_last_ = kC;
param.vd_last_ = kD;
std::string result;
const char *src_data = src_info.c_str();
char *out_data_ptr = NULL;
int total_byte = FillData(src_data, strlen(src_data), &out_data_ptr);
//char * data_BIT_OF_GROUP = out_data_ptr;
for (int i = 0; i < total_byte / (BIT_OF_GROUP / BIT_OF_BYTE); ++i) {
char * data_BIT_OF_GROUP = out_data_ptr;
data_BIT_OF_GROUP += i*(BIT_OF_GROUP / BIT_OF_BYTE);
RotationCalculate(data_BIT_OF_GROUP, param);
}
if (NULL != out_data_ptr) {
delete[] out_data_ptr, out_data_ptr = NULL;
}
result.append(GetHexStr(param.ua_));
result.append(GetHexStr(param.ub_));
result.append(GetHexStr(param.uc_));
result.append(GetHexStr(param.ud_));
return result;
}
#include <iostream>
#include <cmath>
#include "md5_encode.h"
int main()
{
std::string src = "123456";
Md5Encode encode_obj;
std::string ret = encode_obj.Encode(src);
std::cout << "info: " << src.c_str() << std::endl;
std::cout << "md5: " << ret.c_str() << std::endl;
return 0;
}
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