MD5的介紹，演算法和實現。 ――――娃娃/[CCG] (23千字)

MD5的介紹，演算法和實現
                          Wrote By 娃娃/[CCG]



最近對各種加密演算法很感興趣 原因有好多：破解TMG的KeyGenme失敗；羨慕偽哥的永珍序號產生器；佩服夜月大哥和Stkman大哥的密碼學功力………… 偶然間跟Stkman大哥談起來MD5，他給了我很多幫助 使得我可以寫出這篇文章。

MD5簡介：

MD5的全稱是Message-Digest Algorithm 5，在90年代初由MIT的電腦科學實驗室和RSA Data Security Inc發明，經MD2、MD3和MD4發展而來。

Message-Digest泛指位元組串(Message)的Hash變換，就是把一個任意長度的位元組串變換成一定長的大整數。請注意我使用了“位元組串”而不是“字串”這個詞，是因為這種變換隻與位元組的值有關，與字符集或編碼方式無關。

MD5將任意長度的“位元組串”變換成一個128bit的大整數，並且它是一個不可逆的字串變換演算法，（我剛開始還愚蠢的認為MD5是可逆的演算法 感謝Stkman大哥的講解）換句話說就是，即使你看到源程式和演算法描述，也無法將一個MD5的值變換回原始的字串，從數學原理上說，是因為原始的字串有無窮多個，這有點象不存在反函式的數學函式。

MD5的典型應用是對一段Message(位元組串)產生fingerprint(指紋)，以防止被“篡改”。舉個例子，你將一段話寫在一個叫readme.txt檔案中，並對這個readme.txt產生一個MD5的值並記錄在案，然後你可以傳播這個檔案給別人，別人如果修改了檔案中的任何內容，你對這個檔案重新計算MD5時就會發現。如果再有一個第三方的認證機構，用MD5還可以防止檔案作者的“抵賴”，這就是所謂的數字簽名應用。

MD5還廣泛用於加密和解密技術上，在很多作業系統中，使用者的密碼是以MD5值（或類似的其它演算法）的方式儲存的， 使用者Login的時候，系統是把使用者輸入的密碼計算成MD5值，然後再去和系統中儲存的MD5值進行比較，而系統並不“知道”使用者的密碼是什麼。

一些駭客破獲這種密碼的方法是一種被稱為“跑字典”的方法。有兩種方法得到字典，一種是日常蒐集的用做密碼的字串表，另一種是用排列組合方法生成的，先用MD5程式計算出這些字典項的MD5值，然後再用目標的MD5值在這個字典中檢索。

即使假設密碼的最大長度為8，同時密碼只能是字母和數字，共26+26+10=62個字元，排列組合出的字典的項數則是P(62,1)+P(62,2)….+P(62,8)，那也已經是一個很天文的數字了，儲存這個字典就需要TB級的磁碟組，而且這種方法還有一個前提，就是能獲得目標賬戶的密碼MD5值的情況下才可以。

在軟體的加密保護中 很多軟體採用MD5保護  但是由於MD5演算法為不可逆演算法 所以所有的軟體都是使用MD5演算法作為一個加密的中間步驟，比如對使用者名稱做一個MD5變換,結果再進行一個可逆的加密變換，做序號產生器時也只要先用MD5變換，然後再用一個逆演算法。所以對於破解者來說只要能看出是MD5就很容易了。

MD5程式碼的特點明顯，跟蹤時很容易發現，如果軟體採用MD5演算法，在資料初始化的時候必然用到以下的四個常數
0x67452301;
0xefcdab89;
0x98badcfe;
0x10325476;
若常數不等 則可能是變形的MD5演算法 或者根本就不是這個演算法。在記憶體了也就是
01 23 45 67 89 ab cd ef fe dc ......32 10    16個位元組
――――――――――――――――――――――――――――――――――――――――――――

MD5演算法：

第一步：增加填充
增加padding使得資料長度（bit為單位）模512為448。如果資料長度正好是模512為448，增加512個填充bit，也就是說填充的個數為1-512。第一個bit為1，其餘全部為0。
第二步：補足長度
將資料長度轉換為64bit的數值，如果長度超過64bit所能表示的資料長度的範圍，值保留最後64bit，增加到前面填充的資料後面，使得最後的資料為512bit的整數倍。也就是32bit的16倍的整數倍。在RFC1321中，32bit稱為一個word。
第三步：初始化變數：
用到4個變數，分別為A、B、C、D，均為32bit長。初始化為：
A: 01 23 45 67
B: 89 ab cd ef
C: fe dc ba 98
D: 76 54 32 10
第四步：資料處理：
首先定義4個輔助函式：
F(X,Y,Z) = XY v not(X) Z
G(X,Y,Z) = XZ v Y not(Z)
H(X,Y,Z) = X xor Y xor Z
I(X,Y,Z) = Y xor (X v not(Z))
其中：XY表示按位與，X v Y表示按位或，not(X)表示按位取反。xor表示按位異或。
函式中的X、Y、Z均為32bit。

定義一個需要用到的陣列：T(i),i取值1-64,T(i)等於abs(sin(i))的4294967296倍的整數部分,i為弧度。
假設前三步處理後的資料長度為32*16*Nbit

第五步：輸出：
最後得到的ABCD為輸出結果，共128bit。A為低位，D為高位。





MD5在程式設計中的實現


下面來看看如何在C語言和VB中實現MD5演算法
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*/
#ifndef PROTOTYPES
#define PROTOTYPES 0
#endif
typedef unsigned char *POINTER;
typedef unsigned short int UINT2;
typedef unsigned long int UINT4;
#if PROTOTYPES
#define PROTO_LIST(list) list
#else
#define PROTO_LIST(list) ()
#endif

―――――――――― MD5.h――――――――――――――――――――――――――――

typedef struct {
  UINT4 state[4];       
  UINT4 count[2];     
  unsigned char buffer[64];                     
} MD5_CTX;

void MD5Init PROTO_LIST ((MD5_CTX *));
void MD5Update PROTO_LIST
  ((MD5_CTX *, unsigned char *, unsigned int));
void MD5Final PROTO_LIST ((unsigned char [16], MD5_CTX *));

※※※※※※※※※MD5C.C※※※※※※※※※※※※※※※※※※※※※※※※
#include "global.h"
#include "md5.h"
#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

static void MD5Transform PROTO_LIST ((UINT4 [4], unsigned char [64]));
static void Encode PROTO_LIST
  ((unsigned char *, UINT4 *, unsigned int));
static void Decode PROTO_LIST
  ((UINT4 *, unsigned char *, unsigned int));
static void MD5_memcpy PROTO_LIST ((POINTER, POINTER, unsigned int));
static void MD5_memset PROTO_LIST ((POINTER, int, unsigned int));

static unsigned char 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
};

/* 定義F G H I 為四個基數

#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) + (UINT4)(ac); \
(a) = ROTATE_LEFT ((a), (s)); \
(a) += (b); \
  }
#define GG(a, b, c, d, x, s, ac) { \
(a) += G ((b), (c), (d)) + (x) + (UINT4)(ac); \
(a) = ROTATE_LEFT ((a), (s)); \
(a) += (b); \
  }
#define HH(a, b, c, d, x, s, ac) { \
(a) += H ((b), (c), (d)) + (x) + (UINT4)(ac); \
(a) = ROTATE_LEFT ((a), (s)); \
(a) += (b); \
  }
#define II(a, b, c, d, x, s, ac) { \
(a) += I ((b), (c), (d)) + (x) + (UINT4)(ac); \
(a) = ROTATE_LEFT ((a), (s)); \
(a) += (b); \
  }

/*開始進行MD5計算
void MD5Init (context)
MD5_CTX *context;                             
{
  context->count[0] = context->count[1] = 0;
  /* 在這裡定義四個常數，也就是我們剛才講到的四個特徵數.

  context->state[0] = 0x67452301;
  context->state[1] = 0xefcdab89;
  context->state[2] = 0x98badcfe;
  context->state[3] = 0x10325476;
}

void MD5Update (context, input, inputLen)
MD5_CTX *context;                               
unsigned char *input;                           
unsigned int inputLen;                 
{
  unsigned int i, index, partLen;

  index = (unsigned int)((context->count[0] >> 3) & 0x3F);

  if ((context->count[0] += ((UINT4)inputLen << 3)) < ((UINT4)inputLen << 3))
context->count[1]++;
  context->count[1] += ((UINT4)inputLen >> 29);

  partLen = 64 - index;

  if (inputLen >= partLen) {
MD5_memcpy
  ((POINTER)&context->buffer[index], (POINTER)input, partLen);
MD5Transform (context->state, context->buffer);

for (i = partLen; i + 63 < inputLen; i += 64)
  MD5Transform (context->state, &input[i]);

index = 0;
  }
  else
i = 0;

  MD5_memcpy
((POINTER)&context->buffer[index], (POINTER)&input[i],
  inputLen-i);
}

void MD5Final (digest, context)
unsigned char digest[16];                 
MD5_CTX *context;                             
{
  unsigned char bits[8];
  unsigned int index, padLen;

  Encode (bits, context->count, 8);

  index = (unsigned int)((context->count[0] >> 3) & 0x3f);
  padLen = (index < 56) ? (56 - index) : (120 - index);
  MD5Update (context, PADDING, padLen);
  MD5Update (context, bits, 8);

  Encode (digest, context->state, 16);
  MD5_memset ((POINTER)context, 0, sizeof (*context));
}

static void MD5Transform (state, block)
UINT4 state[4];
unsigned char block[64];
{
  UINT4 a = state[0], b = state[1], c = state[2], d = state[3], x[16];

  Decode (x, block, 64);

  /* 第一輪迴圈 */
  FF (a, b, c, d, x[ 0], S11, 0xd76aa478); /* 1 */
  FF (d, a, b, c, x[ 1], S12, 0xe8c7b756); /* 2 */
  FF (c, d, a, b, x[ 2], S13, 0x242070db); /* 3 */
  FF (b, c, d, a, x[ 3], S14, 0xc1bdceee); /* 4 */
  FF (a, b, c, d, x[ 4], S11, 0xf57c0faf); /* 5 */
  FF (d, a, b, c, x[ 5], S12, 0x4787c62a); /* 6 */
  FF (c, d, a, b, x[ 6], S13, 0xa8304613); /* 7 */
  FF (b, c, d, a, x[ 7], S14, 0xfd469501); /* 8 */
  FF (a, b, c, d, x[ 8], S11, 0x698098d8); /* 9 */
  FF (d, a, b, c, x[ 9], S12, 0x8b44f7af); /* 10 */
  FF (c, d, a, b, x[10], S13, 0xffff5bb1); /* 11 */
  FF (b, c, d, a, x[11], S14, 0x895cd7be); /* 12 */
  FF (a, b, c, d, x[12], S11, 0x6b901122); /* 13 */
  FF (d, a, b, c, x[13], S12, 0xfd987193); /* 14 */
  FF (c, d, a, b, x[14], S13, 0xa679438e); /* 15 */
  FF (b, c, d, a, x[15], S14, 0x49b40821); /* 16 */

/* 第二輪迴圈 */
  GG (a, b, c, d, x[ 1], S21, 0xf61e2562); /* 17 */
  GG (d, a, b, c, x[ 6], S22, 0xc040b340); /* 18 */
  GG (c, d, a, b, x[11], S23, 0x265e5a51); /* 19 */
  GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa); /* 20 */
  GG (a, b, c, d, x[ 5], S21, 0xd62f105d); /* 21 */
  GG (d, a, b, c, x[10], S22,  0x2441453); /* 22 */
  GG (c, d, a, b, x[15], S23, 0xd8a1e681); /* 23 */
  GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8); /* 24 */
  GG (a, b, c, d, x[ 9], S21, 0x21e1cde6); /* 25 */
  GG (d, a, b, c, x[14], S22, 0xc33707d6); /* 26 */
  GG (c, d, a, b, x[ 3], S23, 0xf4d50d87); /* 27 */
  GG (b, c, d, a, x[ 8], S24, 0x455a14ed); /* 28 */
  GG (a, b, c, d, x[13], S21, 0xa9e3e905); /* 29 */
  GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8); /* 30 */
  GG (c, d, a, b, x[ 7], S23, 0x676f02d9); /* 31 */
  GG (b, c, d, a, x[12], S24, 0x8d2a4c8a); /* 32 */

  /* 第三輪迴圈 */
  HH (a, b, c, d, x[ 5], S31, 0xfffa3942); /* 33 */
  HH (d, a, b, c, x[ 8], S32, 0x8771f681); /* 34 */
  HH (c, d, a, b, x[11], S33, 0x6d9d6122); /* 35 */
  HH (b, c, d, a, x[14], S34, 0xfde5380c); /* 36 */
  HH (a, b, c, d, x[ 1], S31, 0xa4beea44); /* 37 */
  HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9); /* 38 */
  HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60); /* 39 */
  HH (b, c, d, a, x[10], S34, 0xbebfbc70); /* 40 */
  HH (a, b, c, d, x[13], S31, 0x289b7ec6); /* 41 */
  HH (d, a, b, c, x[ 0], S32, 0xeaa127fa); /* 42 */
  HH (c, d, a, b, x[ 3], S33, 0xd4ef3085); /* 43 */
  HH (b, c, d, a, x[ 6], S34,  0x4881d05); /* 44 */
  HH (a, b, c, d, x[ 9], S31, 0xd9d4d039); /* 45 */
  HH (d, a, b, c, x[12], S32, 0xe6db99e5); /* 46 */
  HH (c, d, a, b, x[15], S33, 0x1fa27cf8); /* 47 */
  HH (b, c, d, a, x[ 2], S34, 0xc4ac5665); /* 48 */

  /* 第四輪迴圈 */
  II (a, b, c, d, x[ 0], S41, 0xf4292244); /* 49 */
  II (d, a, b, c, x[ 7], S42, 0x432aff97); /* 50 */
  II (c, d, a, b, x[14], S43, 0xab9423a7); /* 51 */
  II (b, c, d, a, x[ 5], S44, 0xfc93a039); /* 52 */
  II (a, b, c, d, x[12], S41, 0x655b59c3); /* 53 */
  II (d, a, b, c, x[ 3], S42, 0x8f0ccc92); /* 54 */
  II (c, d, a, b, x[10], S43, 0xffeff47d); /* 55 */
  II (b, c, d, a, x[ 1], S44, 0x85845dd1); /* 56 */
  II (a, b, c, d, x[ 8], S41, 0x6fa87e4f); /* 57 */
  II (d, a, b, c, x[15], S42, 0xfe2ce6e0); /* 58 */
  II (c, d, a, b, x[ 6], S43, 0xa3014314); /* 59 */
  II (b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */
  II (a, b, c, d, x[ 4], S41, 0xf7537e82); /* 61 */
  II (d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */
  II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb); /* 63 */
  II (b, c, d, a, x[ 9], S44, 0xeb86d391); /* 64 */

  state[0] += a;
  state[1] += b;
  state[2] += c;
  state[3] += d;

  MD5_memset ((POINTER)x, 0, sizeof (x));

}
static void Encode (output, input, len)
unsigned char *output;
UINT4 *input;
unsigned int len;
{
  unsigned int i, j;

  for (i = 0, j = 0; j < len; i++, j += 4) {
output[j] = (unsigned char)(input[i] & 0xff);
output[j+1] = (unsigned char)((input[i] >> 8) & 0xff);
output[j+2] = (unsigned char)((input[i] >> 16) & 0xff);
output[j+3] = (unsigned char)((input[i] >> 24) & 0xff);
  }
}

static void Decode (output, input, len)
UINT4 *output;
unsigned char *input;
unsigned int len;
{
  unsigned int i, j;

  for (i = 0, j = 0; j < len; i++, j += 4)
output[i] = ((UINT4)input[j]) | (((UINT4)input[j+1]) << 8) |
  (((UINT4)input[j+2]) << 16) | (((UINT4)input[j+3]) << 24);
}

static void MD5_memcpy (output, input, len)
POINTER output;
POINTER input;
unsigned int len;
{
  unsigned int i;

  for (i = 0; i < len; i++) output[i] = input[i];
}

static void MD5_memset (output, value, len)
POINTER output;
int value;
unsigned int len;
{
  unsigned int i;

  for (i = 0; i < len; i++)
((char *)output)[i] = (char)value;
}
――――――――――――――――C程式碼結束――――――――――


在VB中實現MD5演算法
――――――――――――――――――――――――――――――――――――――――――
Option Explicit

Dim w1 As String, w2 As String, w3 As String, w4 As String

Function MD5F(ByVal tempstr As String, ByVal w As String, ByVal X As String, ByVal y As String, ByVal z As String, ByVal Xin As String, ByVal qdata As String, ByVal rots As Integer)
MD5F = BigMod32Add(RotLeft(BigMod32Add(BigMod32Add(w, tempstr), BigMod32Add(Xin, qdata)), rots), X)
End Function

Sub MD5F1(w As String, ByVal X As String, ByVal y As String, ByVal z As String, ByVal Xin As String, ByVal qdata As String, ByVal rots As Integer)
Dim tempstr As String

    tempstr = BigXOR(z, BigAND(X, BigXOR(y, z)))
    w = MD5F(tempstr, w, X, y, z, Xin, qdata, rots)
End Sub

Sub MD5F2(w As String, ByVal X As String, ByVal y As String, ByVal z As String, ByVal Xin As String, ByVal qdata As String, ByVal rots As Integer)
Dim tempstr As String

    tempstr = BigXOR(y, BigAND(z, BigXOR(X, y)))
    w = MD5F(tempstr, w, X, y, z, Xin, qdata, rots)
End Sub

Sub MD5F3(w As String, ByVal X As String, ByVal y As String, ByVal z As String, ByVal Xin As String, ByVal qdata As String, ByVal rots As Integer)
Dim tempstr As String

    tempstr = BigXOR(X, BigXOR(y, z))
    w = MD5F(tempstr, w, X, y, z, Xin, qdata, rots)
End Sub

Sub MD5F4(w As String, ByVal X As String, ByVal y As String, ByVal z As String, ByVal Xin As String, ByVal qdata As String, ByVal rots As Integer)
Dim tempstr As String

    tempstr = BigXOR(y, BigOR(X, BigNOT(z)))
    w = MD5F(tempstr, w, X, y, z, Xin, qdata, rots)
End Sub

Function MD5_Calc(ByVal hashthis As String) As String
ReDim buf(0 To 3) As String
ReDim Xin(0 To 15) As String
Dim tempnum As Integer, tempnum2 As Integer, loopit As Integer, loopouter As Integer, loopinner As Integer
Dim a As String, b As String, c As String, d As String

    tempnum = 8 * Len(hashthis)
    hashthis = hashthis + Chr$(128) 'Add binary 10000000
    tempnum2 = 56 - Len(hashthis) Mod 64

    If tempnum2 < 0 Then
        tempnum2 = 64 + tempnum2
    End If

    hashthis = hashthis + String$(tempnum2, Chr$(0))

    For loopit = 1 To 8
        hashthis = hashthis + Chr$(tempnum Mod 256)
        tempnum = tempnum - tempnum Mod 256
        tempnum = tempnum / 256
    Next loopit

   
    buf(0) = "67452301"
    buf(1) = "efcdab89"
    buf(2) = "98badcfe"
    buf(3) = "10325476"

   
For loopouter = 0 To Len(hashthis) / 64 - 1
        a = buf(0)
        b = buf(1)
        c = buf(2)
        d = buf(3)

        ' Get the 512 bits
        For loopit = 0 To 15
            Xin(loopit) = ""
            For loopinner = 1 To 4
                Xin(loopit) = Hex$(Asc(Mid$(hashthis, 64 * loopouter + 4 * loopit + loopinner, 1))) + Xin(loopit)
                If Len(Xin(loopit)) Mod 2 Then Xin(loopit) = "0" + Xin(loopit)
            Next loopinner
        Next loopit

       

' 第一輪迴圈
        MD5F1 a, b, c, d, Xin(0), "d76aa478", 7
        MD5F1 d, a, b, c, Xin(1), "e8c7b756", 12
        MD5F1 c, d, a, b, Xin(2), "242070db", 17
        MD5F1 b, c, d, a, Xin(3), "c1bdceee", 22
        MD5F1 a, b, c, d, Xin(4), "f57c0faf", 7
        MD5F1 d, a, b, c, Xin(5), "4787c62a", 12
        MD5F1 c, d, a, b, Xin(6), "a8304613", 17
        MD5F1 b, c, d, a, Xin(7), "fd469501", 22
        MD5F1 a, b, c, d, Xin(8), "698098d8", 7
        MD5F1 d, a, b, c, Xin(9), "8b44f7af", 12
        MD5F1 c, d, a, b, Xin(10), "ffff5bb1", 17
        MD5F1 b, c, d, a, Xin(11), "895cd7be", 22
        MD5F1 a, b, c, d, Xin(12), "6b901122", 7
        MD5F1 d, a, b, c, Xin(13), "fd987193", 12
        MD5F1 c, d, a, b, Xin(14), "a679438e", 17
        MD5F1 b, c, d, a, Xin(15), "49b40821", 22

        ' 第二輪迴圈
        MD5F2 a, b, c, d, Xin(1), "f61e2562", 5
        MD5F2 d, a, b, c, Xin(6), "c040b340", 9
        MD5F2 c, d, a, b, Xin(11), "265e5a51", 14
        MD5F2 b, c, d, a, Xin(0), "e9b6c7aa", 20
        MD5F2 a, b, c, d, Xin(5), "d62f105d", 5
        MD5F2 d, a, b, c, Xin(10), "02441453", 9
        MD5F2 c, d, a, b, Xin(15), "d8a1e681", 14
        MD5F2 b, c, d, a, Xin(4), "e7d3fbc8", 20
        MD5F2 a, b, c, d, Xin(9), "21e1cde6", 5
        MD5F2 d, a, b, c, Xin(14), "c33707d6", 9
        MD5F2 c, d, a, b, Xin(3), "f4d50d87", 14
        MD5F2 b, c, d, a, Xin(8), "455a14ed", 20
        MD5F2 a, b, c, d, Xin(13), "a9e3e905", 5
        MD5F2 d, a, b, c, Xin(2), "fcefa3f8", 9
        MD5F2 c, d, a, b, Xin(7), "676f02d9", 14
        MD5F2 b, c, d, a, Xin(12), "8d2a4c8a", 20

        ' 第三輪迴圈
        MD5F3 a, b, c, d, Xin(5), "fffa3942", 4
        MD5F3 d, a, b, c, Xin(8), "8771f681", 11
        MD5F3 c, d, a, b, Xin(11), "6d9d6122", 16
        MD5F3 b, c, d, a, Xin(14), "fde5380c", 23
        MD5F3 a, b, c, d, Xin(1), "a4beea44", 4
        MD5F3 d, a, b, c, Xin(4), "4bdecfa9", 11
        MD5F3 c, d, a, b, Xin(7), "f6bb4b60", 16
        MD5F3 b, c, d, a, Xin(10), "bebfbc70", 23
        MD5F3 a, b, c, d, Xin(13), "289b7ec6", 4
        MD5F3 d, a, b, c, Xin(0), "e27fa", 11
        MD5F3 c, d, a, b, Xin(3), "d4ef3085", 16
        MD5F3 b, c, d, a, Xin(6), "04881d05", 23
        MD5F3 a, b, c, d, Xin(9), "d9d4d039", 4
        MD5F3 d, a, b, c, Xin(12), "e6db99e5", 11
        MD5F3 c, d, a, b, Xin(15), "1fa27cf8", 16
        MD5F3 b, c, d, a, Xin(2), "c4ac5665", 23

        ' 第四輪迴圈
        MD5F4 a, b, c, d, Xin(0), "f4292244", 6
        MD5F4 d, a, b, c, Xin(7), "432aff97", 10
        MD5F4 c, d, a, b, Xin(14), "ab9423a7", 15
        MD5F4 b, c, d, a, Xin(5), "fc93a039", 21
        MD5F4 a, b, c, d, Xin(12), "655b59c3", 6
        MD5F4 d, a, b, c, Xin(3), "8f0ccc92", 10
        MD5F4 c, d, a, b, Xin(10), "ffeff47d", 15
        MD5F4 b, c, d, a, Xin(1), "85845dd1", 21
        MD5F4 a, b, c, d, Xin(8), "6fa87e4f", 6
        MD5F4 d, a, b, c, Xin(15), "fe2ce6e0", 10
        MD5F4 c, d, a, b, Xin(6), "a3014314", 15
        MD5F4 b, c, d, a, Xin(13), "4e0811a1", 21
        MD5F4 a, b, c, d, Xin(4), "f7537e82", 6
        MD5F4 d, a, b, c, Xin(11), "bd3af235", 10
        MD5F4 c, d, a, b, Xin(2), "2ad7d2bb", 15
        MD5F4 b, c, d, a, Xin(9), "eb86d391", 21

        buf(0) = BigAdd(buf(0), a)
        buf(1) = BigAdd(buf(1), b)
        buf(2) = BigAdd(buf(2), c)
        buf(3) = BigAdd(buf(3), d)
    Next loopouter

    hashthis = ""
    For loopit = 0 To 3
        For loopinner = 3 To 0 Step -1
            hashthis = hashthis + Chr(Val("&H" + Mid$(buf(loopit), 1 + 2 * loopinner, 2)))
        Next loopinner
    Next loopit

MD5_Calc = hashthis
End Function

Function BigMod32Add(ByVal value1 As String, ByVal value2 As String) As String
    BigMod32Add = Right$(BigAdd(value1, value2), 8)
End Function

Public Function BigAdd(ByVal value1 As String, ByVal value2 As String) As String
Dim valueans As String
Dim loopit As Integer, tempnum As Integer

    tempnum = Len(value1) - Len(value2)
    If tempnum < 0 Then
        value1 = Space$(Abs(tempnum)) + value1
    ElseIf tempnum > 0 Then
        value2 = Space$(Abs(tempnum)) + value2
    End If

    tempnum = 0
    For loopit = Len(value1) To 1 Step -1
        tempnum = tempnum + Val("&H" + Mid$(value1, loopit, 1)) + Val("&H" + Mid$(value2, loopit, 1))
        valueans = Hex$(tempnum Mod 16) + valueans
        tempnum = Int(tempnum / 16)
    Next loopit

    If tempnum <> 0 Then
        valueans = Hex$(tempnum) + valueans
    End If

    BigAdd = Right(valueans, 8)
End Function

Public Function RotLeft(ByVal value1 As String, ByVal rots As Integer) As String
Dim tempstr As String
Dim loopit As Integer, loopinner As Integer
Dim tempnum As Integer

    rots = rots Mod 32
   
    If rots = 0 Then
        RotLeft = value1
        Exit Function
    End If

    value1 = Right$(value1, 8)
    tempstr = String$(8 - Len(value1), "0") + value1
    value1 = ""

    ' 轉換成二進位制形式
    For loopit = 1 To 8
        tempnum = Val("&H" + Mid$(tempstr, loopit, 1))
        For loopinner = 3 To 0 Step -1
            If tempnum And 2 ^ loopinner Then
                value1 = value1 + "1"
            Else
                value1 = value1 + "0"
            End If
        Next loopinner
    Next loopit
    tempstr = Mid$(value1, rots + 1) + Left$(value1, rots)

    ' 轉換為十六進位制
    value1 = ""
    For loopit = 0 To 7
        tempnum = 0
        For loopinner = 0 To 3
            If Val(Mid$(tempstr, 4 * loopit + loopinner + 1, 1)) Then

                tempnum = tempnum + 2 ^ (3 - loopinner)
            End If
        Next loopinner
        value1 = value1 + Hex$(tempnum)
    Next loopit

    RotLeft = Right(value1, 8)
End Function

Function BigAND(ByVal value1 As String, ByVal value2 As String) As String
Dim valueans As String
Dim loopit As Integer, tempnum As Integer

    tempnum = Len(value1) - Len(value2)
    If tempnum < 0 Then
        value2 = Mid$(value2, Abs(tempnum) + 1)
    ElseIf tempnum > 0 Then
        value1 = Mid$(value1, tempnum + 1)
    End If

    For loopit = 1 To Len(value1)
        valueans = valueans + Hex$(Val("&H" + Mid$(value1, loopit, 1)) And Val("&H" + Mid$(value2, loopit, 1)))
    Next loopit

    BigAND = valueans
End Function

Function BigNOT(ByVal value1 As String) As String
Dim valueans As String
Dim loopit As Integer

    value1 = Right$(value1, 8)
    value1 = String$(8 - Len(value1), "0") + value1
    For loopit = 1 To 8
        valueans = valueans + Hex$(15 Xor Val("&H" + Mid$(value1, loopit, 1)))
    Next loopit

    BigNOT = valueans
End Function

Function BigOR(ByVal value1 As String, ByVal value2 As String) As String
Dim valueans As String
Dim loopit As Integer, tempnum As Integer

    tempnum = Len(value1) - Len(value2)
    If tempnum < 0 Then
        valueans = Left$(value2, Abs(tempnum))
        value2 = Mid$(value2, Abs(tempnum) + 1)
    ElseIf tempnum > 0 Then
        valueans = Left$(value1, Abs(tempnum))
        value1 = Mid$(value1, tempnum + 1)
    End If

    For loopit = 1 To Len(value1)
        valueans = valueans + Hex$(Val("&H" + Mid$(value1, loopit, 1)) Or Val("&H" + Mid$(value2, loopit, 1)))
    Next loopit

    BigOR = valueans
End Function

Function BigXOR(ByVal value1 As String, ByVal value2 As String) As String
Dim valueans As String
Dim loopit As Integer, tempnum As Integer

    tempnum = Len(value1) - Len(value2)
    If tempnum < 0 Then
        valueans = Left$(value2, Abs(tempnum))
        value2 = Mid$(value2, Abs(tempnum) + 1)
    ElseIf tempnum > 0 Then
        valueans = Left$(value1, Abs(tempnum))
        value1 = Mid$(value1, tempnum + 1)
    End If

    For loopit = 1 To Len(value1)
        valueans = valueans + Hex$(Val("&H" + Mid$(value1, loopit, 1)) Xor Val("&H" + Mid$(value2, loopit, 1)))
    Next loopit

    BigXOR = Right(valueans, 8)
End Function
――――――――――――――――――――――――――――――――――――――――――――

呵呵 洋洋灑灑的一大篇可是我查詢了不少資料才寫出來 ^_^ 大概可以當成我們學校的Assignment了 呵呵 感謝大家看完    最後給大家出到題吧 大家可以試試自己的運氣啊 就是：
51E5D4BD3323A02CCCDD0472AE2DC20B  這組數是我透過MD5演算法加密一組字串後產生的一組密碼 大家猜猜我加密的字串是什麼  ^_^ 提示一下――――加空格一共20位  ^_^ 

^_^  88




僅以次文獻給我們可愛的組織CCG 希望它能蒸蒸日上！

娃娃(NYDoll)
屬於中國破解組織CHiNA CrACKiNG GrOUp