[C#] - MD5 加密的具体流程
来源：http://www.chinaitpower.com/A/2005-05-13/116840.html
1.来历 MD5的全称是message-digest algorithm 5(信息-摘要算法，在90年代初由mit laboratory for computer science和rsa data security inc的ronald l. rivest开发出来，经md2、md3和md4发展而来。http://www.ietf.org/rfc/rfc1321.txt，是一份最权威的文档，由ronald l. rivest在1992年8月向ieft提交。 2.用途 MD5的作用是对一段信息(message)生成信息摘要(message-digest)，该摘要对该信息具有唯一性,可以作为数字签名。用于验证文件的有效性(是否有丢失或损坏的数据),对用户密码的加密，在哈希函数中计算散列值。 3.特点 输入一个任意长度的字节串，生成一个128位的整数。由于算法的某些不可逆特征，在加密应用上有较好的安全性。并且，MD5算法的使用不需要支付任何版权费用。 4.说明 唯一性和不可逆性都不是绝对的，从理论上分析是一种多对一的关系，但两个不同的信息产生相同摘要的概率很小。不可逆是指从输出反推输入所需的运算量和计算时间太大，使用穷搜字典的方法又需要太多的存储空间。 5.算法描述 算法输入是一个字节串，每个字节是8个bit. 算法的执行分为以下几个步骤： 第一步，补位： MD5算法先对输入的数据进行补位，使得数据的长度(以byte为单位)对64求余的结果是56。即数据扩展至LEN=K*64+56个字节，K为整数。 补位方法：补一个1，然后补0至满足上述要求。相当于补一个0x80的字节，再补值为0的字节。这一步里总共补充的字节数为0～63个。 第二步，附加数据长度： 用一个64位的整数表示数据的原始长度(以bit为单位)，将这个数字的8个字节按低位的在前，高位在后的顺序附加在补位后的数据后面。这时，数据被填补后的总长度为： LEN = K*64+56+8=(K+1)*64 Bytes。
※注意那个64位整数是输入数据的原始长度而不是填充字节后的长度,我就在这里栽了跟头. 第三步，初始化MD5参数： 有四个32位整数变量 (A,B,C,D) 用来计算信息摘要，每一个变量被初始化成以下以十六进制数表示的数值，低位的字节在前面。 word A: 01 23 45 67 word B: 89 ab cd ef word C: fe dc ba 98 word D: 76 54 32 10 ※注意低位的字节在前面指的是Little Endian平台上内存中字节的排列方式，而在程序中书写时，要写成： A=0x67452301 B=0xefcdab89 C=0x98badcfe D=0x10325476 第四步，定义四个MD5基本的按位操作函数： X，Y，Z为32位整数。 F(X,Y,Z) = (X and Y) or (not(X) and Z) G(X,Y,Z) = (X and Z) or (Y and not(Z)) H(X,Y,Z) = X xor Y xor Z I(X,Y,Z) = Y xor (X or not(Z)) 再定义四个分别用于四轮变换的函数。 设Mj表示消息的第j个子分组（从0到15），<<<s表示循环左移s位，则四种操作为： 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) 第五步，对输入数据作变换。 处理数据，N是总的字节数，以64个字节为一组，每组作一次循环，每次循环进行四轮操作。要变换的64个字节用16个32位的整数数组M[0 ...15]表示。而数组T[1 ... 64]表示一组常数， T[i]为4294967296*abs(sin(i))的32位整数部分，i的单位是弧度,i的取值从1到64。 具体过程如下：
/* 设置主循环变量 */ For i = 0 to N/16-1 do /*每循环一次，把数据原文存放在16个元素的数组X中. */ For j = 0 to 15 do Set X[j] to M[i*16+j]. end /结束对J的循环 /* Save A as AA, B as BB, C as CC, and D as DD. */ AA = A BB = B CC = C DD = D /* 第1轮*/ /* 以 [abcd k s i]表示如下操作 a = b + ((a + F(b,c,d) + X[k] + T[i]) <<< s). */ /* Do the following 16 operations. */ [ABCD 0 7 1] [DABC 1 12 2] [CDAB 2 17 3] [BCDA 3 22 4] [ABCD 4 7 5] [DABC 5 12 6] [CDAB 6 17 7] [BCDA 7 22 8] [ABCD 8 7 9] [DABC 9 12 10] [CDAB 10 17 11] [BCDA 11 22 12] [ABCD 12 7 13] [DABC 13 12 14] [CDAB 14 17 15] [BCDA 15 22 16] /* 第2轮* */ /* 以 [abcd k s i]表示如下操作 a = b + ((a + G(b,c,d) + X[k] + T[i]) <<< s). */ /* Do the following 16 operations. */ [ABCD 1 5 17] [DABC 6 9 18] [CDAB 11 14 19] [BCDA 0 20 20] [ABCD 5 5 21] [DABC 10 9 22] [CDAB 15 14 23] [BCDA 4 20 24] [ABCD 9 5 25] [DABC 14 9 26] [CDAB 3 14 27] [BCDA 8 20 28] [ABCD 13 5 29] [DABC 2 9 30] [CDAB 7 14 31] [BCDA 12 20 32] /* 第3轮*/ /* 以 [abcd k s i]表示如下操作 a = b + ((a + H(b,c,d) + X[k] + T[i]) <<< s). */ /* Do the following 16 operations. */ [ABCD 5 4 33] [DABC 8 11 34] [CDAB 11 16 35] [BCDA 14 23 36] [ABCD 1 4 37] [DABC 4 11 38] [CDAB 7 16 39] [BCDA 10 23 40] [ABCD 13 4 41] [DABC 0 11 42] [CDAB 3 16 43] [BCDA 6 23 44] [ABCD 9 4 45] [DABC 12 11 46] [CDAB 15 16 47] [BCDA 2 23 48] /* 第4轮*/ /* 以 [abcd k s i]表示如下操作 a = b + ((a + I(b,c,d) + X[k] + T[i]) <<< s). */ /* Do the following 16 operations. */ [ABCD 0 6 49] [DABC 7 10 50] [CDAB 14 15 51] [BCDA 5 21 52] [ABCD 12 6 53] [DABC 3 10 54] [CDAB 10 15 55] [BCDA 1 21 56] [ABCD 8 6 57] [DABC 15 10 58] [CDAB 6 15 59] [BCDA 13 21 60] [ABCD 4 6 61] [DABC 11 10 62] [CDAB 2 15 63] [BCDA 9 21 64] /* 然后进行如下操作 */ A = A + AA B = B + BB C = C + CC D = D + DD Next i /* 结束对I的循环*/
第六步，输出结果。
A，B，C，D连续存放，共16个字节，128位。按十六进制依次输出这个16个字节。
最后，用程序语言实现算法后，可以输入以下几个信息对程序作一个简单的测试，看看程序有没有错误。
MD5 ("") = d41d8cd98f00b204e9800998ecf8427e
MD5 ("a") = 0cc175b9c0f1b6a831c399e269772661
MD5 ("abc") = 900150983cd24fb0d6963f7d28e17f72
MD5 ("message digest") = f96b697d7cb7938d525a2f31aaf161d0
MD5 ("abcdefghijklmnopqrstuvwxyz") = c3fcd3d76192e4007dfb496cca67e13b
MD5 ("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789") = d174ab98d277d9f5a5611c2c9f419d9f
MD5 ("12345678901234567890123456789012345678901234567890123456789012345678901234567890") = 57edf4a22be3c955ac49da2e2107b67a
MD5算法之C#程序
MD5算法比较特别，最适合用汇编语言来写，好多高级语言对之无能无力或效率极低。比如我最开始尝试用Python和Euphoria编写，发现不太容易。相比而言，C#作为C家簇中新兴的一门.net语言，功能比较全面。花了一晚上的工夫终于用C#最先实现了MD5。主要是由于对算法的一些细节不太注意，结果输出总是不对，调试了好长时间。
//源文件：md5.cs
// MD5 Alogrithm
// by rufi 2004.6.20 http://rufi.yculblog.com/
using System;
using System.Collections;
using System.IO;
public class MD5
{
//static state variables
private static UInt32 A;
private static UInt32 B;
private static UInt32 C;
private static UInt32 D;
//number of bits to rotate in tranforming
private const int S11 = 7;
private const int S12 = 12;
private const int S13 = 17;
private const int S14 = 22;
private const int S21 = 5;
private const int S22 = 9;
private const int S23 = 14;
private const int S24 = 20;
private const int S31 = 4;
private const int S32 = 11;
private const int S33 = 16;
private const int S34 = 23;
private const int S41 = 6;
private const int S42 = 10;
private const int S43 = 15;
private const int S44 = 21;
/* F, G, H and I are basic MD5 functions.
* 四个非线性函数:
*
* 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))
*
* （&与，|或，~非，^异或）
*/
private static UInt32 F(UInt32 x, UInt32 y, UInt32 z)
{
return (x & y) | ((~x) & z);
}
private static UInt32 G(UInt32 x, UInt32 y, UInt32 z)
{
return (x & z) | (y & (~z));
}
private static UInt32 H(UInt32 x, UInt32 y, UInt32 z)
{
return x ^ y ^ z;
}
private static UInt32 I(UInt32 x, UInt32 y, UInt32 z)
{
return y ^ (x | (~z));
}
/* FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
* Rotation is separate from addition to prevent recomputation.
*/
private static void FF(ref UInt32 a, UInt32 b, UInt32 c, UInt32 d, UInt32 mj, int s, UInt32 ti)
{
a = a + F(b, c, d) + mj + ti;
a = a << s | a >> (32 - s);
a += b;
}
private static void GG(ref UInt32 a, UInt32 b, UInt32 c, UInt32 d, UInt32 mj, int s, UInt32 ti)
{
a = a + G(b, c, d) + mj + ti;
a = a << s | a >> (32 - s);
a += b;
}
private static void HH(ref UInt32 a, UInt32 b, UInt32 c, UInt32 d, UInt32 mj, int s, UInt32 ti)
{
a = a + H(b, c, d) + mj + ti;
a = a << s | a >> (32 - s);
a += b;
}
private static void II(ref UInt32 a, UInt32 b, UInt32 c, UInt32 d, UInt32 mj, int s, UInt32 ti)
{
a = a + I(b, c, d) + mj + ti;
a = a << s | a >> (32 - s);
a += b;
}
private static void MD5_Init()
{
A = 0x67452301; //in memory, this is 0x01234567
B = 0xefcdab89; //in memory, this is 0x89abcdef
C = 0x98badcfe; //in memory, this is 0xfedcba98
D = 0x10325476; //in memory, this is 0x76543210
}
private static UInt32[] MD5_Append(byte[] input)
{
int zeros = 0;
int ones = 1;
int size = 0;
int n = input.Length;
int m = n % 64;
if (m < 56)
{
zeros = 55 - m;
size = n - m + 64;
}
else if (m == 56)
{
zeros = 0;
ones = 0;
size = n + 8;
}
else
{
zeros = 63 - m + 56;
size = n + 64 - m + 64;
}
ArrayList bs = new ArrayList(input);
if (ones == 1)
{
bs.Add((byte)0x80); // 0x80 = $10000000
}
for (int i = 0; i < zeros; i++)
{
bs.Add((byte)0);
}
UInt64 N = (UInt64)n * 8;
byte h1 = (byte)(N & 0xFF);
byte h2 = (byte)((N >> 8) & 0xFF);
byte h3 = (byte)((N >> 16) & 0xFF);
byte h4 = (byte)((N >> 24) & 0xFF);
byte h5 = (byte)((N >> 32) & 0xFF);
byte h6 = (byte)((N >> 40) & 0xFF);
byte h7 = (byte)((N >> 48) & 0xFF);
byte h8 = (byte)(N >> 56);
bs.Add(h1);
bs.Add(h2);
bs.Add(h3);
bs.Add(h4);
bs.Add(h5);
bs.Add(h6);
bs.Add(h7);
bs.Add(h8);
byte[] ts = (byte[])bs.ToArray(typeof(byte));
/* Decodes input (byte[]) into output (UInt32[]). Assumes len is
* a multiple of 4.
*/
UInt32[] output = new UInt32[size / 4];
for (Int64 i = 0, j = 0; i < size; j++, i += 4)
{
output[j] = (UInt32)(ts[i] | ts[i + 1] << 8 | ts[i + 2] << 16 | ts[i + 3] << 24);
}
return output;
}
private static UInt32[] MD5_Trasform(UInt32[] x)
{
UInt32 a, b, c, d;
for (int k = 0; k < x.Length; k += 16)
{
a = A;
b = B;
c = C;
d = D;
/* Round 1 */
FF(ref a, b, c, d, x[k + 0], S11, 0xd76aa478); /* 1 */
FF(ref d, a, b, c, x[k + 1], S12, 0xe8c7b756); /* 2 */
FF(ref c, d, a, b, x[k + 2], S13, 0x242070db); /* 3 */
FF(ref b, c, d, a, x[k + 3], S14, 0xc1bdceee); /* 4 */
FF(ref a, b, c, d, x[k + 4], S11, 0xf57c0faf); /* 5 */
FF(ref d, a, b, c, x[k + 5], S12, 0x4787c62a); /* 6 */
FF(ref c, d, a, b, x[k + 6], S13, 0xa8304613); /* 7 */
FF(ref b, c, d, a, x[k + 7], S14, 0xfd469501); /* 8 */
FF(ref a, b, c, d, x[k + 8], S11, 0x698098d8); /* 9 */
FF(ref d, a, b, c, x[k + 9], S12, 0x8b44f7af); /* 10 */
FF(ref c, d, a, b, x[k + 10], S13, 0xffff5bb1); /* 11 */
FF(ref b, c, d, a, x[k + 11], S14, 0x895cd7be); /* 12 */
FF(ref a, b, c, d, x[k + 12], S11, 0x6b901122); /* 13 */
FF(ref d, a, b, c, x[k + 13], S12, 0xfd987193); /* 14 */
FF(ref c, d, a, b, x[k + 14], S13, 0xa679438e); /* 15 */
FF(ref b, c, d, a, x[k + 15], S14, 0x49b40821); /* 16 */
/* Round 2 */
GG(ref a, b, c, d, x[k + 1], S21, 0xf61e2562); /* 17 */
GG(ref d, a, b, c, x[k + 6], S22, 0xc040b340); /* 18 */
GG(ref c, d, a, b, x[k + 11], S23, 0x265e5a51); /* 19 */
GG(ref b, c, d, a, x[k + 0], S24, 0xe9b6c7aa); /* 20 */
GG(ref a, b, c, d, x[k + 5], S21, 0xd62f105d); /* 21 */
GG(ref d, a, b, c, x[k + 10], S22, 0x2441453); /* 22 */
GG(ref c, d, a, b, x[k + 15], S23, 0xd8a1e681); /* 23 */
GG(ref b, c, d, a, x[k + 4], S24, 0xe7d3fbc8); /* 24 */
GG(ref a, b, c, d, x[k + 9], S21, 0x21e1cde6); /* 25 */
GG(ref d, a, b, c, x[k + 14], S22, 0xc33707d6); /* 26 */
GG(ref c, d, a, b, x[k + 3], S23, 0xf4d50d87); /* 27 */
GG(ref b, c, d, a, x[k + 8], S24, 0x455a14ed); /* 28 */
GG(ref a, b, c, d, x[k + 13], S21, 0xa9e3e905); /* 29 */
GG(ref d, a, b, c, x[k + 2], S22, 0xfcefa3f8); /* 30 */
GG(ref c, d, a, b, x[k + 7], S23, 0x676f02d9); /* 31 */
GG(ref b, c, d, a, x[k + 12], S24, 0x8d2a4c8a); /* 32 */
/* Round 3 */
HH(ref a, b, c, d, x[k + 5], S31, 0xfffa3942); /* 33 */
HH(ref d, a, b, c, x[k + 8], S32, 0x8771f681); /* 34 */
HH(ref c, d, a, b, x[k + 11], S33, 0x6d9d6122); /* 35 */
HH(ref b, c, d, a, x[k + 14], S34, 0xfde5380c); /* 36 */
HH(ref a, b, c, d, x[k + 1], S31, 0xa4beea44); /* 37 */
HH(ref d, a, b, c, x[k + 4], S32, 0x4bdecfa9); /* 38 */
HH(ref c, d, a, b, x[k + 7], S33, 0xf6bb4b60); /* 39 */
HH(ref b, c, d, a, x[k + 10], S34, 0xbebfbc70); /* 40 */
HH(ref a, b, c, d, x[k + 13], S31, 0x289b7ec6); /* 41 */
HH(ref d, a, b, c, x[k + 0], S32, 0xeaa127fa); /* 42 */
HH(ref c, d, a, b, x[k + 3], S33, 0xd4ef3085); /* 43 */
HH(ref b, c, d, a, x[k + 6], S34, 0x4881d05); /* 44 */
HH(ref a, b, c, d, x[k + 9], S31, 0xd9d4d039); /* 45 */
HH(ref d, a, b, c, x[k + 12], S32, 0xe6db99e5); /* 46 */
HH(ref c, d, a, b, x[k + 15], S33, 0x1fa27cf8); /* 47 */
HH(ref b, c, d, a, x[k + 2], S34, 0xc4ac5665); /* 48 */
/* Round 4 */
II(ref a, b, c, d, x[k + 0], S41, 0xf4292244); /* 49 */
II(ref d, a, b, c, x[k + 7], S42, 0x432aff97); /* 50 */
II(ref c, d, a, b, x[k + 14], S43, 0xab9423a7); /* 51 */
II(ref b, c, d, a, x[k + 5], S44, 0xfc93a039); /* 52 */
II(ref a, b, c, d, x[k + 12], S41, 0x655b59c3); /* 53 */
II(ref d, a, b, c, x[k + 3], S42, 0x8f0ccc92); /* 54 */
II(ref c, d, a, b, x[k + 10], S43, 0xffeff47d); /* 55 */
II(ref b, c, d, a, x[k + 1], S44, 0x85845dd1); /* 56 */
II(ref a, b, c, d, x[k + 8], S41, 0x6fa87e4f); /* 57 */
II(ref d, a, b, c, x[k + 15], S42, 0xfe2ce6e0); /* 58 */
II(ref c, d, a, b, x[k + 6], S43, 0xa3014314); /* 59 */
II(ref b, c, d, a, x[k + 13], S44, 0x4e0811a1); /* 60 */
II(ref a, b, c, d, x[k + 4], S41, 0xf7537e82); /* 61 */
II(ref d, a, b, c, x[k + 11], S42, 0xbd3af235); /* 62 */
II(ref c, d, a, b, x[k + 2], S43, 0x2ad7d2bb); /* 63 */
II(ref b, c, d, a, x[k + 9], S44, 0xeb86d391); /* 64 */
A += a;
B += b;
C += c;
D += d;
}
return new UInt32[] { A, B, C, D };
}
public static byte[] MD5Array(byte[] input)
{
MD5_Init();
UInt32[] block = MD5_Append(input);
UInt32[] bits = MD5_Trasform(block);
/* Encodes bits (UInt32[]) into output (byte[]). Assumes len is
* a multiple of 4.
*/
byte[] output = new byte[bits.Length * 4];
for (int i = 0, j = 0; i < bits.Length; i++, j += 4)
{
output[j] = (byte)(bits[i] & 0xff);
output[j + 1] = (byte)((bits[i] >> 8) & 0xff);
output[j + 2] = (byte)((bits[i] >> 16) & 0xff);
output[j + 3] = (byte)((bits[i] >> 24) & 0xff);
}
return output;
}
public static string ArrayToHexString(byte[] array, bool uppercase)
{
string hexString = "";
string format = "x2";
if (uppercase)
{
format = "X2";
}
foreach (byte b in array)
{
hexString += b.ToString(format);
}
return hexString;
}
public static string MDString(string message)
{
char[] c = message.ToCharArray();
byte[] b = new byte[c.Length];
for (int i = 0; i < c.Length; i++)
{
b[i] = (byte)c[i];
}
byte[] digest = MD5Array(b);
return ArrayToHexString(digest, false);
}
public static string MDFile(string fileName)
{
FileStream fs = File.Open(fileName, FileMode.Open, FileAccess.Read);
byte[] array = new byte[fs.Length];
fs.Read(array, 0, (int)fs.Length);
byte[] digest = MD5Array(array);
fs.Close();
return ArrayToHexString(digest, false);
}
public static string Test(string message)
{
return "rnMD5 (" + message + ") = " + MD5.MDString(message);
}
static void Main(string[] args)
{
Console.WriteLine(Test(""));
Console.WriteLine();
Console.WriteLine(Test("a"));
Console.WriteLine();
Console.WriteLine(Test("abc"));
Console.WriteLine();
Console.WriteLine(Test("message digest"));
Console.WriteLine();
Console.WriteLine(Test("abcdefghijklmnopqrstuvwxyz"));
Console.WriteLine();
Console.WriteLine(Test("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"));
Console.WriteLine();
Console.WriteLine(Test("12345678901234567890123456789012345678901234567890123456789012345678901234567890"));
Console.ReadLine();
}
}
