我做了研究，但在网上找不到任何东西。
有些站点解释了该算法，但是没有人通过示例来解决它。
和内置的类，我看不到它们做什么以及如何做。
答案 0 :(得分：1)
这是实现：
public class MD5
{
/***********************VARIABLES************************************/
/***********************Statics**************************************/
/// <summary>
/// lookup table 4294967296*sin(i)
/// </summary>
protected readonly static uint [] T =new uint[64]
{ 0xd76aa478,0xe8c7b756,0x242070db,0xc1bdceee,
0xf57c0faf,0x4787c62a,0xa8304613,0xfd469501,
0x698098d8,0x8b44f7af,0xffff5bb1,0x895cd7be,
0x6b901122,0xfd987193,0xa679438e,0x49b40821,
0xf61e2562,0xc040b340,0x265e5a51,0xe9b6c7aa,
0xd62f105d,0x2441453,0xd8a1e681,0xe7d3fbc8,
0x21e1cde6,0xc33707d6,0xf4d50d87,0x455a14ed,
0xa9e3e905,0xfcefa3f8,0x676f02d9,0x8d2a4c8a,
0xfffa3942,0x8771f681,0x6d9d6122,0xfde5380c,
0xa4beea44,0x4bdecfa9,0xf6bb4b60,0xbebfbc70,
0x289b7ec6,0xeaa127fa,0xd4ef3085,0x4881d05,
0xd9d4d039,0xe6db99e5,0x1fa27cf8,0xc4ac5665,
0xf4292244,0x432aff97,0xab9423a7,0xfc93a039,
0x655b59c3,0x8f0ccc92,0xffeff47d,0x85845dd1,
0x6fa87e4f,0xfe2ce6e0,0xa3014314,0x4e0811a1,
0xf7537e82,0xbd3af235,0x2ad7d2bb,0xeb86d391};
/*****instance variables**************/
/// <summary>
/// X used to proces data in
/// 512 bits chunks as 16 32 bit word
/// </summary>
protected uint [] X = new uint [16];
/// <summary>
/// the finger print obtained.
/// </summary>
protected Digest dgFingerPrint;
/// <summary>
/// the input bytes
/// </summary>
protected byte [] m_byteInput;
/**********************EVENTS AND DELEGATES*******************************************/
public delegate void ValueChanging (object sender,MD5ChangingEventArgs Changing);
public delegate void ValueChanged (object sender,MD5ChangedEventArgs Changed);
public event ValueChanging OnValueChanging;
public event ValueChanged OnValueChanged;
/********************************************************************/
/***********************PROPERTIES ***********************/
/// <summary>
///gets or sets as string
/// </summary>
public string Value
{
get
{
string st ;
char [] tempCharArray= new Char[m_byteInput.Length];
for(int i =0; i<m_byteInput.Length;i++)
tempCharArray[i]=(char)m_byteInput[i];
st= new String(tempCharArray);
return st;
}
set
{
/// raise the event to notify the changing
if (this.OnValueChanging !=null)
this.OnValueChanging(this,new MD5ChangingEventArgs(value));
m_byteInput=new byte[value.Length];
for (int i =0; i<value.Length;i++)
m_byteInput[i]=(byte)value[i];
dgFingerPrint=CalculateMD5Value();
/// raise the event to notify the change
if (this.OnValueChanged !=null)
this.OnValueChanged(this,new MD5ChangedEventArgs(value,dgFingerPrint.ToString()));
}
}
/// <summary>
/// get/sets as byte array
/// </summary>
public byte [] ValueAsByte
{
get
{
byte [] bt = new byte[m_byteInput.Length];
for (int i =0; i<m_byteInput.Length;i++)
bt[i]=m_byteInput[i];
return bt;
}
set
{
/// raise the event to notify the changing
if (this.OnValueChanging !=null)
this.OnValueChanging(this,new MD5ChangingEventArgs(value));
m_byteInput=new byte[value.Length];
for (int i =0; i<value.Length;i++)
m_byteInput[i]=value[i];
dgFingerPrint=CalculateMD5Value();
/// notify the changed value
if (this.OnValueChanged !=null)
this.OnValueChanged(this,new MD5ChangedEventArgs(value,dgFingerPrint.ToString()));
}
}
//gets the signature/figner print as string
public string FingerPrint
{
get
{
return dgFingerPrint.ToString();
}
}
/*************************************************************************/
/// <summary>
/// Constructor
/// </summary>
public MD5()
{
Value="";
}
/******************************************************************************/
/*********************METHODS**************************/
/// <summary>
/// calculat md5 signature of the string in Input
/// </summary>
/// <returns> Digest: the finger print of msg</returns>
protected Digest CalculateMD5Value()
{
/***********vairable declaration**************/
byte [] bMsg; //buffer to hold bits
uint N; //N is the size of msg as word (32 bit)
Digest dg =new Digest(); // the value to be returned
// create a buffer with bits padded and length is alos padded
bMsg=CreatePaddedBuffer();
N=(uint)(bMsg.Length*8)/32; //no of 32 bit blocks
for (uint i=0; i<N/16;i++)
{
CopyBlock(bMsg,i);
PerformTransformation(ref dg.A,ref dg.B,ref dg.C,ref dg.D);
}
return dg;
}
/********************************************************
* TRANSFORMATIONS : FF , GG , HH , II acc to RFC 1321
* where each Each letter represnets the aux function used
*********************************************************/
/// <summary>
/// perform transformatio using f(((b&c) | (~(b)&d))
/// </summary>
protected void TransF(ref uint a, uint b, uint c, uint d,uint k,ushort s, uint i )
{
a = b + MD5Helper.RotateLeft((a + ((b&c) | (~(b)&d)) + X[k] + T[i-1]), s);
}
/// <summary>
/// perform transformatio using g((b&d) | (c & ~d) )
/// </summary>
protected void TransG(ref uint a, uint b, uint c, uint d,uint k,ushort s, uint i )
{
a = b + MD5Helper.RotateLeft((a + ((b&d) | (c & ~d) ) + X[k] + T[i-1]), s);
}
/// <summary>
/// perform transformatio using h(b^c^d)
/// </summary>
protected void TransH(ref uint a, uint b, uint c, uint d,uint k,ushort s, uint i )
{
a = b + MD5Helper.RotateLeft((a + (b^c^d) + X[k] + T[i-1]), s);
}
/// <summary>
/// perform transformatio using i (c^(b|~d))
/// </summary>
protected void TransI(ref uint a, uint b, uint c, uint d,uint k,ushort s, uint i )
{
a = b + MD5Helper.RotateLeft((a + (c^(b|~d))+ X[k] + T[i-1]), s);
}
/// <summary>
/// Perform All the transformation on the data
/// </summary>
/// <param name="A">A</param>
/// <param name="B">B </param>
/// <param name="C">C</param>
/// <param name="D">D</param>
protected void PerformTransformation(ref uint A,ref uint B,ref uint C, ref uint D)
{
//// saving ABCD to be used in end of loop
uint AA,BB,CC,DD;
AA=A;
BB=B;
CC=C;
DD=D;
/* Round 1
* [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]
* * */
TransF(ref A,B,C,D,0,7,1);TransF(ref D,A,B,C,1,12,2);TransF(ref C,D,A,B,2,17,3);TransF(ref B,C,D,A,3,22,4);
TransF(ref A,B,C,D,4,7,5);TransF(ref D,A,B,C,5,12,6);TransF(ref C,D,A,B,6,17,7);TransF(ref B,C,D,A,7,22,8);
TransF(ref A,B,C,D,8,7,9);TransF(ref D,A,B,C,9,12,10);TransF(ref C,D,A,B,10,17,11);TransF(ref B,C,D,A,11,22,12);
TransF(ref A,B,C,D,12,7,13);TransF(ref D,A,B,C,13,12,14);TransF(ref C,D,A,B,14,17,15);TransF(ref B,C,D,A,15,22,16);
/** rOUND 2
**[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]
*/
TransG(ref A,B,C,D,1,5,17);TransG(ref D,A,B,C,6,9,18);TransG(ref C,D,A,B,11,14,19);TransG(ref B,C,D,A,0,20,20);
TransG(ref A,B,C,D,5,5,21);TransG(ref D,A,B,C,10,9,22);TransG(ref C,D,A,B,15,14,23);TransG(ref B,C,D,A,4,20,24);
TransG(ref A,B,C,D,9,5,25);TransG(ref D,A,B,C,14,9,26);TransG(ref C,D,A,B,3,14,27);TransG(ref B,C,D,A,8,20,28);
TransG(ref A,B,C,D,13,5,29);TransG(ref D,A,B,C,2,9,30);TransG(ref C,D,A,B,7,14,31);TransG(ref B,C,D,A,12,20,32);
/* rOUND 3
* [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]
* */
TransH(ref A,B,C,D,5,4,33);TransH(ref D,A,B,C,8,11,34);TransH(ref C,D,A,B,11,16,35);TransH(ref B,C,D,A,14,23,36);
TransH(ref A,B,C,D,1,4,37);TransH(ref D,A,B,C,4,11,38);TransH(ref C,D,A,B,7,16,39);TransH(ref B,C,D,A,10,23,40);
TransH(ref A,B,C,D,13,4,41);TransH(ref D,A,B,C,0,11,42);TransH(ref C,D,A,B,3,16,43);TransH(ref B,C,D,A,6,23,44);
TransH(ref A,B,C,D,9,4,45);TransH(ref D,A,B,C,12,11,46);TransH(ref C,D,A,B,15,16,47);TransH(ref B,C,D,A,2,23,48);
/*ORUNF 4
*[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]
* */
TransI(ref A,B,C,D,0,6,49);TransI(ref D,A,B,C,7,10,50);TransI(ref C,D,A,B,14,15,51);TransI(ref B,C,D,A,5,21,52);
TransI(ref A,B,C,D,12,6,53);TransI(ref D,A,B,C,3,10,54);TransI(ref C,D,A,B,10,15,55);TransI(ref B,C,D,A,1,21,56);
TransI(ref A,B,C,D,8,6,57);TransI(ref D,A,B,C,15,10,58);TransI(ref C,D,A,B,6,15,59);TransI(ref B,C,D,A,13,21,60);
TransI(ref A,B,C,D,4,6,61);TransI(ref D,A,B,C,11,10,62);TransI(ref C,D,A,B,2,15,63);TransI(ref B,C,D,A,9,21,64);
A=A+AA;
B=B+BB;
C=C+CC;
D=D+DD;
}
/// <summary>
/// Create Padded buffer for processing , buffer is padded with 0 along
/// with the size in the end
/// </summary>
/// <returns>the padded buffer as byte array</returns>
protected byte[] CreatePaddedBuffer()
{
uint pad; //no of padding bits for 448 mod 512
byte [] bMsg; //buffer to hold bits
ulong sizeMsg; //64 bit size pad
uint sizeMsgBuff; //buffer size in multiple of bytes
int temp=(448-((m_byteInput.Length*8)%512)); //temporary
pad = (uint )((temp+512)%512); //getting no of bits to be pad
if (pad==0) ///pad is in bits
pad=512; //at least 1 or max 512 can be added
sizeMsgBuff= (uint) ((m_byteInput.Length)+ (pad/8)+8);
sizeMsg=(ulong)m_byteInput.Length*8;
bMsg=new byte[sizeMsgBuff]; ///no need to pad with 0 coz new bytes
// are already initialize to 0 :)
////copying string to buffer
for (int i =0; i<m_byteInput.Length;i++)
bMsg[i]=m_byteInput[i];
bMsg[m_byteInput.Length]|=0x80; ///making first bit of padding 1,
//wrting the size value
for (int i =8; i >0;i--)
bMsg[sizeMsgBuff-i]=(byte) (sizeMsg>>((8-i)*8) & 0x00000000000000ff);
return bMsg;
}
/// <summary>
/// Copies a 512 bit block into X as 16 32 bit words
/// </summary>
/// <param name="bMsg"> source buffer</param>
/// <param name="block">no of block to copy starting from 0</param>
protected void CopyBlock(byte[] bMsg,uint block)
{
block=block<<6;
for (uint j=0; j<61;j+=4)
{
X[j>>2]=(((uint) bMsg[block+(j+3)]) <<24 ) |
(((uint) bMsg[block+(j+2)]) <<16 ) |
(((uint) bMsg[block+(j+1)]) <<8 ) |
(((uint) bMsg[block+(j)]) ) ;
}
}
}