using System;
using System.Collections.Generic;
using System.Linq;
using System.Text; namespace WindowsFormsApplication1
{
/// <summary>
/// 加密解密QQ消息包的工具类.
/// </summary>
public static class QQCrypter
{
private static void code(byte[] In, int inOffset, int inPos, byte[] Out, int outOffset, int outPos, byte[] key)
{
if (outPos > )
{
for (int i = ; i < ; i++)
{
In[outOffset + outPos + i] = (byte)(In[inOffset + inPos + i] ^ Out[outOffset + outPos + i - ]);
}
}
uint[] formattedKey = FormatKey(key);
uint y = ConvertByteArrayToUInt(In, outOffset + outPos);
uint z = ConvertByteArrayToUInt(In, outOffset + outPos + );
uint sum = ;
uint delta = 0x9e3779b9;
uint n = ; while (n-- > )
{
sum += delta;
y += ((z << ) + formattedKey[]) ^ (z + sum) ^ ((z >> ) + formattedKey[]);
z += ((y << ) + formattedKey[]) ^ (y + sum) ^ ((y >> ) + formattedKey[]);
}
Array.Copy(ConvertUIntToByteArray(y), , Out, outOffset + outPos, );
Array.Copy(ConvertUIntToByteArray(z), , Out, outOffset + outPos + , );
if (inPos > )
{
for (int i = ; i < ; i++)
{
Out[outOffset + outPos + i] = (byte)(Out[outOffset + outPos + i] ^ In[inOffset + inPos + i - ]);
}
}
} private static void decode(byte[] In, int inOffset, int inPos, byte[] Out, int outOffset, int outPos, byte[] key)
{
if (outPos > )
{
for (int i = ; i < ; i++)
{
Out[outOffset + outPos + i] = (byte)(In[inOffset + inPos + i] ^ Out[outOffset + outPos + i - ]);
}
}
else
{
Array.Copy(In, inOffset, Out, outOffset, );
}
uint[] formattedKey = FormatKey(key);
uint y = ConvertByteArrayToUInt(Out, outOffset + outPos);
uint z = ConvertByteArrayToUInt(Out, outOffset + outPos + );
uint sum = 0xE3779B90;
uint delta = 0x9e3779b9;
uint n = ; while (n-- > )
{
z -= ((y << ) + formattedKey[]) ^ (y + sum) ^ ((y >> ) + formattedKey[]);
y -= ((z << ) + formattedKey[]) ^ (z + sum) ^ ((z >> ) + formattedKey[]);
sum -= delta;
}
Array.Copy(ConvertUIntToByteArray(y), , Out, outOffset + outPos, );
Array.Copy(ConvertUIntToByteArray(z), , Out, outOffset + outPos + , );
} /**/
/// <summary>
/// 解密
/// </summary>
/// <param name="In">密文</param>
/// <param name="offset">密文开始的位置</param>
/// <param name="len">密文长度</param>
/// <param name="key">密钥</param>
/// <returns>返回明文</returns>
public static byte[] Decrypt(byte[] In, int offset, int len, byte[] key)
{
// 因为QQ消息加密之后至少是16字节，并且肯定是8的倍数，这里检查这种情况
if ((len % != ) || (len < ))
{
return null;
}
byte[] Out = new byte[len];
for (int i = ; i < len; i += )
{
decode(In, offset, i, Out, , i, key);
}
for (int i = ; i < len; i++)
{
Out[i] = (byte)(Out[i] ^ In[offset + i - ]);
}
int pos = Out[] & 0x07;
len = len - pos - ;
byte[] res = new byte[len];
Array.Copy(Out, pos + , res, , len);
return res;
} public static byte[] Encrypt(byte[] In, int offset, int len, byte[] key)
{
// 计算头部填充字节数
int pos = (len + ) % ;
if (pos != )
{
pos = - pos;
}
byte[] plain = new byte[len + pos + ];
Random Rnd = new Random();
plain[] = (byte)((Rnd.Next() & 0xF8) | pos);
for (int i = ; i < pos + ; i++)
{
plain[i] = (byte)(Rnd.Next() & 0xFF);
}
Array.Copy(In, , plain, pos + , len);
for (int i = pos + + len; i < plain.Length; i++)
{
plain[i] = 0x0;
}
// 定义输出流
byte[] outer = new byte[len + pos + ];
for (int i = ; i < outer.Length; i += )
{
code(plain, , i, outer, , i, key);
}
return outer;
} private static uint[] FormatKey(byte[] key)
{
if (key.Length == )
{
throw new ArgumentException("Key must be between 1 and 16 characters in length");
}
byte[] refineKey = new byte[];
if (key.Length < )
{
Array.Copy(key, , refineKey, , key.Length);
for (int k = key.Length; k < ; k++)
{
refineKey[k] = 0x20;
}
}
else
{
Array.Copy(key, , refineKey, , );
}
uint[] formattedKey = new uint[];
int j = ;
for (int i = ; i < refineKey.Length; i += )
{
formattedKey[j++] = ConvertByteArrayToUInt(refineKey, i);
}
return formattedKey;
} private static byte[] ConvertUIntToByteArray(uint v)
{
byte[] result = new byte[];
result[] = (byte)((v >> ) & 0xFF);
result[] = (byte)((v >> ) & 0xFF);
result[] = (byte)((v >> ) & 0xFF);
result[] = (byte)((v >> ) & 0xFF);
return result;
} private static uint ConvertByteArrayToUInt(byte[] v, int offset)
{
if (offset + > v.Length)
{
return ;
}
uint output;
output = (uint)(v[offset] << );
output |= (uint)(v[offset + ] << );
output |= (uint)(v[offset + ] << );
output |= (uint)(v[offset + ] << );
return output;
}
} }