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 > 0)
{
for (int i = 0; i < 8; i++)
{
In[outOffset + outPos + i] = (byte)(In[inOffset + inPos + i] ^ Out[outOffset + outPos + i - 8]);
}
}
uint[] formattedKey = FormatKey(key);
uint y = ConvertByteArrayToUInt(In, outOffset + outPos);
uint z = ConvertByteArrayToUInt(In, outOffset + outPos + 4);
uint sum = 0;
uint delta = 0x9e3779b9;
uint n = 16;
while (n-- > 0)
{
sum += delta;
y += ((z << 4) + formattedKey[0]) ^ (z + sum) ^ ((z >> 5) + formattedKey[1]);
z += ((y << 4) + formattedKey[2]) ^ (y + sum) ^ ((y >> 5) + formattedKey[3]);
}
Array.Copy(ConvertUIntToByteArray(y), 0, Out, outOffset + outPos, 4);
Array.Copy(ConvertUIntToByteArray(z), 0, Out, outOffset + outPos + 4, 4);
if (inPos > 0)
{
for (int i = 0; i < 8; i++)
{
Out[outOffset + outPos + i] = (byte)(Out[outOffset + outPos + i] ^ In[inOffset + inPos + i - 8]);
}
}
}
private static void decode(byte[] In, int inOffset, int inPos, byte[] Out, int outOffset, int outPos, byte[] key)
{
if (outPos > 0)
{
for (int i = 0; i < 8; i++)
{
Out[outOffset + outPos + i] = (byte)(In[inOffset + inPos + i] ^ Out[outOffset + outPos + i - 8]);
}
}
else
{
Array.Copy(In, inOffset, Out, outOffset, 8);
}
uint[] formattedKey = FormatKey(key);
uint y = ConvertByteArrayToUInt(Out, outOffset + outPos);
uint z = ConvertByteArrayToUInt(Out, outOffset + outPos + 4);
uint sum = 0xE3779B90;
uint delta = 0x9e3779b9;
uint n = 16;
while (n-- > 0)
{
z -= ((y << 4) + formattedKey[2]) ^ (y + sum) ^ ((y >> 5) + formattedKey[3]);
y -= ((z << 4) + formattedKey[0]) ^ (z + sum) ^ ((z >> 5) + formattedKey[1]);
sum -= delta;
}
Array.Copy(ConvertUIntToByteArray(y), 0, Out, outOffset + outPos, 4);
Array.Copy(ConvertUIntToByteArray(z), 0, Out, outOffset + outPos + 4, 4);
}
/**/
/// <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 % 8 != 0) || (len < 16))
{
return null;
}
byte[] Out = new byte[len];
for (int i = 0; i < len; i += 8)
{
decode(In, offset, i, Out, 0, i, key);
}
for (int i = 8; i < len; i++)
{
Out[i] = (byte)(Out[i] ^ In[offset + i - 8]);
}
int pos = Out[0] & 0x07;
len = len - pos - 10;
byte[] res = new byte[len];
Array.Copy(Out, pos + 3, res, 0, 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 + 10) % 8;
if (pos != 0)
{
pos = 8 - pos;
}
byte[] plain = new byte[len + pos + 10];
Random Rnd = new Random();
plain[0] = (byte)((Rnd.Next() & 0xF8) | pos);
for (int i = 1; i < pos + 3; i++)
{
plain[i] = (byte)(Rnd.Next() & 0xFF);
}
Array.Copy(In, 0, plain, pos + 3, len);
for (int i = pos + 3 + len; i < plain.Length; i++)
{
plain[i] = 0x0;
}
// 定义输出流
byte[] outer = new byte[len + pos + 10];
for (int i = 0; i < outer.Length; i += 8)
{
code(plain, 0, i, outer, 0, i, key);
}
return outer;
}
private static uint[] FormatKey(byte[] key)
{
if (key.Length == 0)
{
throw new ArgumentException("Key must be between 1 and 16 characters in length");
}
byte[] refineKey = new byte[16];
if (key.Length < 16)
{
Array.Copy(key, 0, refineKey, 0, key.Length);
for (int k = key.Length; k < 16; k++)
{
refineKey[k] = 0x20;
}
}
else
{
Array.Copy(key, 0, refineKey, 0, 16);
}
uint[] formattedKey = new uint[4];
int j = 0;
for (int i = 0; i < refineKey.Length; i += 4)
{
formattedKey[j++] = ConvertByteArrayToUInt(refineKey, i);
}
return formattedKey;
}
private static byte[] ConvertUIntToByteArray(uint v)
{
byte[] result = new byte[4];
result[0] = (byte)((v >> 24) & 0xFF);
result[1] = (byte)((v >> 16) & 0xFF);
result[2] = (byte)((v >> 8) & 0xFF);
result[3] = (byte)((v >> 0) & 0xFF);
return result;
}
private static uint ConvertByteArrayToUInt(byte[] v, int offset)
{
if (offset + 4 > v.Length)
{
return 0;
}
uint output;
output = (uint)(v[offset] << 24);
output |= (uint)(v[offset + 1] << 16);
output |= (uint)(v[offset + 2] << 8);
output |= (uint)(v[offset + 3] << 0);
return output;
}
}
}
