我正在尝试对字符串实现 md5 加密，但找不到任何工作算法示例。我做了研究，但除了解释算法的教程之外在网上找不到任何东西或者无论如何我可以在内置类中找到代码
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)]) ) ;
}
}
}
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