/// <summary>
/// 拆包
/// </summary>
/// <param name="buff">源文件字节数组</param>
/// <returns>原始文件字节数组</returns>
public static byte[] Unpackage(byte[] buff)
{
try
{
if (Encoding.UTF8.GetString(buff, 0, _key.Length) != _key)
{
return(null);
}
ulong l = BitConverter.ToUInt64(buff, _key.Length + 19);
byte[] mbuf = new byte[l];
Buffer.BlockCopy(buff, 15 + 19, mbuf, 0, (int)l);
byte[] desbuff = DesByte.Decrypt(mbuf);
byte[] outbuff = new byte[desbuff.Length + buff.Length - 15 - 19 - (int)l];
Buffer.BlockCopy(desbuff, 0, outbuff, 0, desbuff.Length);
Buffer.BlockCopy(buff, 15 + 19 + (int)l, outbuff, desbuff.Length, buff.Length - 15 - 19 - (int)l);
return(outbuff);
}
catch (Exception ex)
{
throw ex;
}
}
/// <summary>
/// 打包
/// </summary>
/// <param name="buff">源文件字节数组</param>
/// <param name="lastWritenTime">源文件最后修改日期</param>
/// <returns>打包后的字节数组</returns>
public static byte[] Package(byte[] buff, string lastWritenTime)
{
byte[] keyBuff = Encoding.UTF8.GetBytes(_key);
byte[] desbuff = null;
byte[] otherbuff = null;
byte[] tmBuff = Encoding.UTF8.GetBytes(lastWritenTime);
if (buff.Length < _stampLength)
{
desbuff = DesByte.Encrypt(buff);
}
else
{
byte[] cutbuff = new byte[_stampLength];
Buffer.BlockCopy(buff, 0, cutbuff, 0, _stampLength);
desbuff = DesByte.Encrypt(cutbuff);
otherbuff = new byte[buff.Length - _stampLength];
Buffer.BlockCopy(buff, _stampLength, otherbuff, 0, otherbuff.Length);
}
byte[] bodyLengthBuff = BitConverter.GetBytes((ulong)desbuff.Length);
//to combine
byte[] outBuff = new byte[keyBuff.Length + tmBuff.Length + bodyLengthBuff.Length + desbuff.Length + (otherbuff == null ? 0 : otherbuff.Length)];
Buffer.BlockCopy(keyBuff, 0, outBuff, 0, keyBuff.Length);
Buffer.BlockCopy(tmBuff, 0, outBuff, keyBuff.Length, tmBuff.Length);
Buffer.BlockCopy(bodyLengthBuff, 0, outBuff, keyBuff.Length + tmBuff.Length, bodyLengthBuff.Length);
Buffer.BlockCopy(desbuff, 0, outBuff, keyBuff.Length + tmBuff.Length + bodyLengthBuff.Length, desbuff.Length);
if (otherbuff != null)
{
Buffer.BlockCopy(otherbuff, 0, outBuff, keyBuff.Length + tmBuff.Length + bodyLengthBuff.Length + desbuff.Length, otherbuff.Length);
}
return(outBuff);
}
