private static ServerConnection ProcessServer(Socket s)
{
byte[] test = new byte[23];
s.Receive(test);
Console.WriteLine(Encoding.ASCII.GetString(test));
ServerConnection conn = new ServerConnection();
conn.Sock = s;
conn.Aes = new AesCryptoServiceProvider();
if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
{
using (RSACng rsa = new RSACng(3072))
{
var bytes = new byte[3072];
conn.Sock.Receive(bytes);
rsa.ImportRSAPublicKey(bytes, out _);
conn.Sock.Send(rsa.Encrypt(conn.Aes.Key, RSAEncryptionPadding.Pkcs1));
}
}
else
{
using (RSAOpenSsl rsa = new RSAOpenSsl(3072))
{
var bytes = new byte[3072];
conn.Sock.Receive(bytes);
rsa.ImportRSAPublicKey(bytes, out _);
conn.Sock.Send(rsa.Encrypt(conn.Aes.Key, RSAEncryptionPadding.Pkcs1));
}
}
var headerBytes = new byte[20];
conn.Sock.Receive(headerBytes);
conn.Aes.IV = headerBytes.Take(16).ToArray();
int msgLength = BitConverter.ToInt32(headerBytes.Skip(16).Take(4).ToArray());
var encryptedBytes = new byte[msgLength];
conn.Sock.Receive(encryptedBytes);
string msg;
using (MemoryStream ms = new MemoryStream(encryptedBytes))
{
using (CryptoStream cs = new CryptoStream(ms, conn.Aes.CreateDecryptor(), CryptoStreamMode.Read))
{
using (StreamReader sr = new StreamReader(cs))
{
msg = sr.ReadToEnd();
}
}
}
if (msg != "OK!")
{
throw new Exception("Server didn't return \"OK!\"");
}
return(conn);
}
private static RSA BuildRsaPublicKey(byte[] encodedData)
{
RSA rsa = new RSAOpenSsl();
try
{
rsa.ImportRSAPublicKey(new ReadOnlySpan <byte>(encodedData), out _);
}
catch (Exception)
{
rsa.Dispose();
throw;
}
return(rsa);
}