/// <summary>
/// Waits for a handshake from the server.
/// </summary>
/// <param name="rsa">The RSA crypter.</param>
/// <exception cref="ArgumentNullException">
/// <paramref name="rsa" /> is <see langword="null" />.
/// </exception>
protected bool WaitForHandshake(RSACryptoServiceProvider rsa)
{
if (rsa == null)
{
throw new ArgumentNullException("rsa");
}
byte[] buffer;
buffer = this.Stream.WaitAndRead(2);
if (buffer.Length != 2)
{
return(false);
}
// content length
var contentLength = buffer.ToUInt16().Value;
if (contentLength < 1)
{
// no data
return(false);
}
buffer = this.Stream.WaitAndRead(contentLength);
if (buffer.Length != contentLength)
{
return(false);
}
var uncrypted = rsa.Decrypt(buffer, false);
if (uncrypted.Length < 1)
{
return(false);
}
CryptAlgorithm algo;
if (!Enum.TryParse <CryptAlgorithm>(uncrypted[0].ToString(), out algo))
{
return(false);
}
ICrypter crypter = null;
switch (algo)
{
case CryptAlgorithm.UNKNOWN:
break;
case CryptAlgorithm.Rijndael:
crypter = RijndaelCrypter.FromParameters(uncrypted.Skip(1));
break;
default:
throw new NotImplementedException(algo.ToString());
}
if (crypter == null)
{
return(false);
}
this.Crypter = crypter;
return(true);
}
/// <summary>
/// Waits for a handshake from client.
/// </summary>
protected bool WaitForHandshake()
{
byte[] buffer;
buffer = this.Stream.WaitAndRead(1);
if (buffer.Length != 1)
{
return(false);
}
var version = buffer[0];
if (version != 1)
{
// not supported
return(false);
}
buffer = this.Stream.WaitAndRead(2);
if (buffer.Length != 2)
{
return(false);
}
var keySize = buffer.ToUInt16().Value;
if (keySize < 1)
{
// no key
return(false);
}
var key = this.Stream.WaitAndRead(keySize);
if (key.Length != keySize)
{
return(false);
}
RijndaelCrypter crypter;
using (var rsa = new RSACryptoServiceProvider())
{
rsa.ImportCspBlob(key);
crypter = new RijndaelCrypter();
byte[] content;
using (var temp = new MemoryStream())
{
// algorithm
var algo = CryptAlgorithm.Rijndael;
temp.WriteByte((byte)algo);
// parameters
var @params = crypter.ExportParameters();
temp.Write(@params, 0, @params.Length);
content = rsa.Encrypt(temp.ToArray(), false);
}
// content length
var contentLength = (ushort)content.Length;
this.Stream.Write(contentLength.GetBytes(), 0, 2);
// content
this.Stream.Write(content, 0, content.Length);
}
this.Crypter = crypter;
return(true);
}
