MD5码现在使用的很广泛，其中不仅在web还是winform上。MD5码是不可逆的，虽然国内某大学女教师连破2种，但是她使用的碰撞算法，她也无法确定第二次就一定破的出来，所以就目前而言是安全的，不过时间长了就会有这种查询数据库出来也就不太安全了，目前有一些网站就可以查一些普通的密码，例如http://md5.rednoize.com/ 查不到的就可以添加进去，这样时间长了就可以查出来。
下面是一个md5算法
MD5算法
//static state variables
private static UInt32 A;
private static UInt32 B;
private static UInt32 C;
private static UInt32 D;
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;
* 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));
}
* 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;
}
{
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
}
{
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;
}
if(ones==1)
{
bs.Add( (byte)0x80 ); // 0x80 = $10000000
}
for(int i=0;i<zeros;i++)
{
bs.Add( (byte)0 );
}
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));
* 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)
{
{
a=A;
b=B;
d=D;
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 */
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 */
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 */
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],
下面是一个md5算法
MD5算法//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],