- 前言
- 一、实验目的
- 二、实验环境
- 三、实验基本方法
- 四、实验程序清单
- 五、实验结果
- 六、实验总结
为了帮助同学们完成痛苦的实验课程设计，本作者将其作出的实验结果及代码贴至CSDN中，供同学们学习参考。如有不足或描述不完善之处，敬请各位指出，欢迎各位的斧正！
一、实验目的1.掌握MD5算法的工作原理。
2.熟悉.NET Framework 4 MD5码编程
3.熟悉MD5的常规应用
Microsoft Visual Studio 2019
三、实验基本方法1.用C语言编写MD5算法，验证MD5原理；（见实验程序清单）
2.用C#编写基于.NET Framework实现字符串的MD5码计算；（见实验程序清单）
3.用C#编写基于.NET Framework文件的MD5码计算；（见实验程序清单）
4.用MD5进行文件完整性校验;（见实验结果）
5.用MD5编写Windows窗体登录界面，实验MD5在身份认证系统中的应用。（见实验结果）
1.分析C语言编写的MD5算法实现。
2.分析程序关键原代码。
3.分析用MD5进行文件完整性校验。
4.分析在系统登录中MD5算法的应用。
源代码修改如下：
#include "stdafx.h"
#include "md5.h"
using namespace std;
#define S11 7
#define S12 12
#define S13 17
#define S14 22
#define S21 5
#define S22 9
#define S23 14
#define S24 20
#define S31 4
#define S32 11
#define S33 16
#define S34 23
#define S41 6
#define S42 10
#define S43 15
#define S44 21
#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z)))
#define ROTATE_LEFt(x, n) (((x) << (n)) | ((x) >> (32-(n))))
#define FF(a, b, c, d, x, s, ac) {
(a) += F ((b), (c), (d)) + (x) + ac;
(a) = ROTATE_LEFt ((a), (s));
(a) += (b);
}
#define GG(a, b, c, d, x, s, ac) {
(a) += G ((b), (c), (d)) + (x) + ac;
(a) = ROTATE_LEFt ((a), (s));
(a) += (b);
}
#define HH(a, b, c, d, x, s, ac) {
(a) += H ((b), (c), (d)) + (x) + ac;
(a) = ROTATE_LEFt ((a), (s));
(a) += (b);
}
#define II(a, b, c, d, x, s, ac) {
(a) += I ((b), (c), (d)) + (x) + ac;
(a) = ROTATE_LEFt ((a), (s));
(a) += (b);
}
const byte MD5::PADDING[64] = { 0x80 };
const char MD5::HEX[16] = {
'0', '1', '2', '3',
'4', '5', '6', '7',
'8', '9', 'a', 'b',
'c', 'd', 'e', 'f'
};
MD5::MD5() {
reset();
}
MD5::MD5(const void* input, size_t length) {
reset();
update(input, length);
}
MD5::MD5(const string& str) {
reset();
update(str);
}
MD5::MD5(ifstream& in) {
reset();
update(in);
}
const byte* MD5::digest() {
if (!_finished) {
_finished = true;
final();
}
return _digest;
}
void MD5::reset() {
_finished = false;
_count[0] = _count[1] = 0;
_state[0] = 0x67452301;
_state[1] = 0xefcdab89;
_state[2] = 0x98badcfe;
_state[3] = 0x10325476;
}
void MD5::update(const void* input, size_t length) {
update((const byte*)input, length);
}
void MD5::update(const string& str) {
update((const byte*)str.c_str(), str.length());
}
void MD5::update(ifstream& in) {
if (!in) {
return;
}
std::streamsize length;
char buffer[BUFFER_SIZE];
while (!in.eof()) {
in.read(buffer, BUFFER_SIZE);
length = in.gcount();
if (length > 0) {
update(buffer, length);
}
}
in.close();
}
void MD5::update(const byte* input, size_t length) {
uint32 i, index, partLen;
_finished = false;
index = (uint32)((_count[0] >> 3) & 0x3f);
if ((_count[0] += ((uint32)length << 3)) < ((uint32)length << 3)) {
++_count[1];
}
_count[1] += ((uint32)length >> 29);
partLen = 64 - index;
if (length >= partLen) {
memcpy(&_buffer[index], input, partLen);
transform(_buffer);
for (i = partLen; i + 63 < length; i += 64) {
transform(&input[i]);
}
index = 0;
} else {
i = 0;
}
memcpy(&_buffer[index], &input[i], length - i);
}
void MD5::final() {
byte bits[8];
uint32 oldState[4];
uint32 oldCount[2];
uint32 index, padLen;
memcpy(oldState, _state, 16);
memcpy(oldCount, _count, 8);
encode(_count, bits, 8);
index = (uint32)((_count[0] >> 3) & 0x3f);
padLen = (index < 56) ? (56 - index) : (120 - index);
update(PADDING, padLen);
update(bits, 8);
encode(_state, _digest, 16);
memcpy(_state, oldState, 16);
memcpy(_count, oldCount, 8);
}
void MD5::transform(const byte block[64]) {
uint32 a = _state[0], b = _state[1], c = _state[2], d = _state[3], x[16];
decode(block, x, 64);
FF (a, b, c, d, x[ 0], S11, 0xd76aa478);
FF (d, a, b, c, x[ 1], S12, 0xe8c7b756);
FF (c, d, a, b, x[ 2], S13, 0x242070db);
FF (b, c, d, a, x[ 3], S14, 0xc1bdceee);
FF (a, b, c, d, x[ 4], S11, 0xf57c0faf);
FF (d, a, b, c, x[ 5], S12, 0x4787c62a);
FF (c, d, a, b, x[ 6], S13, 0xa8304613);
FF (b, c, d, a, x[ 7], S14, 0xfd469501);
FF (a, b, c, d, x[ 8], S11, 0x698098d8);
FF (d, a, b, c, x[ 9], S12, 0x8b44f7af);
FF (c, d, a, b, x[10], S13, 0xffff5bb1);
FF (b, c, d, a, x[11], S14, 0x895cd7be);
FF (a, b, c, d, x[12], S11, 0x6b901122);
FF (d, a, b, c, x[13], S12, 0xfd987193);
FF (c, d, a, b, x[14], S13, 0xa679438e);
FF (b, c, d, a, x[15], S14, 0x49b40821);
GG (a, b, c, d, x[ 1], S21, 0xf61e2562);
GG (d, a, b, c, x[ 6], S22, 0xc040b340);
GG (c, d, a, b, x[11], S23, 0x265e5a51);
GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa);
GG (a, b, c, d, x[ 5], S21, 0xd62f105d);
GG (d, a, b, c, x[10], S22, 0x2441453);
GG (c, d, a, b, x[15], S23, 0xd8a1e681);
GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8);
GG (a, b, c, d, x[ 9], S21, 0x21e1cde6);
GG (d, a, b, c, x[14], S22, 0xc33707d6);
GG (c, d, a, b, x[ 3], S23, 0xf4d50d87);
GG (b, c, d, a, x[ 8], S24, 0x455a14ed);
GG (a, b, c, d, x[13], S21, 0xa9e3e905);
GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8);
GG (c, d, a, b, x[ 7], S23, 0x676f02d9);
GG (b, c, d, a, x[12], S24, 0x8d2a4c8a);
HH (a, b, c, d, x[ 5], S31, 0xfffa3942);
HH (d, a, b, c, x[ 8], S32, 0x8771f681);
HH (c, d, a, b, x[11], S33, 0x6d9d6122);
HH (b, c, d, a, x[14], S34, 0xfde5380c);
HH (a, b, c, d, x[ 1], S31, 0xa4beea44);
HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9);
HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60);
HH (b, c, d, a, x[10], S34, 0xbebfbc70);
HH (a, b, c, d, x[13], S31, 0x289b7ec6);
HH (d, a, b, c, x[ 0], S32, 0xeaa127fa);
HH (c, d, a, b, x[ 3], S33, 0xd4ef3085);
HH (b, c, d, a, x[ 6], S34, 0x4881d05);
HH (a, b, c, d, x[ 9], S31, 0xd9d4d039);
HH (d, a, b, c, x[12], S32, 0xe6db99e5);
HH (c, d, a, b, x[15], S33, 0x1fa27cf8);
HH (b, c, d, a, x[ 2], S34, 0xc4ac5665);
II (a, b, c, d, x[ 0], S41, 0xf4292244);
II (d, a, b, c, x[ 7], S42, 0x432aff97);
II (c, d, a, b, x[14], S43, 0xab9423a7);
II (b, c, d, a, x[ 5], S44, 0xfc93a039);
II (a, b, c, d, x[12], S41, 0x655b59c3);
II (d, a, b, c, x[ 3], S42, 0x8f0ccc92);
II (c, d, a, b, x[10], S43, 0xffeff47d);
II (b, c, d, a, x[ 1], S44, 0x85845dd1);
II (a, b, c, d, x[ 8], S41, 0x6fa87e4f);
II (d, a, b, c, x[15], S42, 0xfe2ce6e0);
II (c, d, a, b, x[ 6], S43, 0xa3014314);
II (b, c, d, a, x[13], S44, 0x4e0811a1);
II (a, b, c, d, x[ 4], S41, 0xf7537e82);
II (d, a, b, c, x[11], S42, 0xbd3af235);
II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb);
II (b, c, d, a, x[ 9], S44, 0xeb86d391);
_state[0] += a;
_state[1] += b;
_state[2] += c;
_state[3] += d;
}
void MD5::encode(const uint32* input, byte* output, size_t length) {
for (size_t i = 0, j = 0; j < length; ++i, j += 4) {
output[j]= (byte)(input[i] & 0xff);
output[j + 1] = (byte)((input[i] >> 8) & 0xff);
output[j + 2] = (byte)((input[i] >> 16) & 0xff);
output[j + 3] = (byte)((input[i] >> 24) & 0xff);
}
}
void MD5::decode(const byte* input, uint32* output, size_t length) {
for (size_t i = 0, j = 0; j < length; ++i, j += 4) {
output[i] = ((uint32)input[j]) | (((uint32)input[j + 1]) << 8) |
(((uint32)input[j + 2]) << 16) | (((uint32)input[j + 3]) << 24);
}
}
string MD5::bytesToHexString(const byte* input, size_t length) {
string str;
str.reserve(length << 1);
for (size_t i = 0; i < length; ++i) {
int t = input[i];
int a = t / 16;
int b = t % 16;
str.append(1, HEX[a]);
str.append(1, HEX[b]);
}
return str;
}
string MD5::toString() {
return bytesToHexString(digest(), 16);
}
编辑MFC对话框如下：
源代码修改如下：
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Security.Cryptography;
using System.IO;
namespace Md5Test
{
public partial class Form1 : Form
{
string fName;
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
byte[] result = Encoding.Default.GetBytes(this.textBox1.Text.Trim());
MD5 md5 = new MD5CryptoServiceProvider();
byte[] output = md5.ComputeHash(result);
this.textBox3.Text = BitConverter.ToString(output).Replace("-", "");
this.textBox4.Text = this.textBox3.Text.Substring(8,16) ;
}
private void button2_Click(object sender, EventArgs e)
{
OpenFileDialog openFileDialog = new OpenFileDialog();
openFileDialog.InitialDirectory = "c:\";
// openFileDialog.Filter = "文本文件|*.*|C#文件|*.cs|所有文件|*.*";
openFileDialog.RestoreDirectory = true;
openFileDialog.FilterIndex = 1; if (openFileDialog.ShowDialog() == DialogResult.OK)
{
fName = openFileDialog.FileName;
textBox2.Text = fName;
}
}
private void button3_Click(object sender, EventArgs e)
{
FileStream file = new FileStream(fName, FileMode.Open);
MD5 md5 = new MD5CryptoServiceProvider();
byte[] retVal = md5.ComputeHash(file);
this.textBox3.Text = BitConverter.ToString(retVal).Replace("-", "");
this.textBox4.Text = this.textBox3.Text.Substring(8, 16);
file.Close();
}
private void button4_Click(object sender, EventArgs e)
{
string Md5Str;
FileStream file = new FileStream(fName, FileMode.Open);
MD5 md5 = new MD5CryptoServiceProvider();
byte[] retVal = md5.ComputeHash(file);
Md5Str = BitConverter.ToString(retVal).Replace("-", "");
file.Close();
if (textBox5.Text.Trim().ToUpper().Equals(Md5Str.ToUpper()))
{
textBox_compare.Visible = true;
textBox_compare.BackColor = Color.LightGreen;
textBox_compare.Text = "MD5码 已匹配，文件未被修改！";
}
else
{
textBox_compare.Visible = true;
textBox_compare.BackColor = Color.Red;
textBox_compare.Text = "MD5码 不匹配，文件已被修改！";
}
}
private void label9_Click(object sender, EventArgs e)
{
}
private void button5_Click(object sender, EventArgs e)
{
Form2 form = new Form2();
form.ShowDialog();
}
private void button6_Click(object sender, EventArgs e)
{
Form3 form = new Form3();
form.ShowDialog();
}
}
}
编辑MFC对话框如下：
输入字符串：
计算：
注册：
登录：
登录成功
当字符串相同的时候，进行两代码计算MD5码的校验：
两代码计算的MD5码相同
选择文件：
计算文件MD5码：
复制粘贴MD5码并进行文件验证：
显示文件未被修改
若对本文件进行修改，再次计算MD5码并验证：
显示文件已被修改
更换登录账户：
进行文件验证：
显示文件未被修改
由于MD5算法具有压缩性强、容易计算、抗修改性强、抗碰撞性强等特点，其主要用于把大容量信息在用数字签名软件签署私人密钥前被"压缩"成一种保密的格式(就是把一个任意长度的字节串变换成一定长的十六进制数字串)。换言之，只要文件被修改过，其MD5码的码值就会被修改，与原来MD5码的码值不匹配。
