/// <summary>
/// Sends the Client Key Exchange message flight.
/// </summary>
/// <param name="Endpoint">Endpoint.</param>
/// <param name="State">Endpoint state.</param>
public override void SendClientKeyExchange(DtlsEndpoint Endpoint, EndpointState State)
{
this.CalcMasterSecret(State);
// Sends the Client Key Exchange message for Pre-shared key ciphers,
// as defined in §2 of RFC 4279: https://tools.ietf.org/html/rfc4279
if (State.credentials is PresharedKey Psk)
{
ushort N = (ushort)Psk.Identity.Length;
byte[] ClientKeyExchange = new byte[2 + N];
ClientKeyExchange[0] = (byte)(N >> 8);
ClientKeyExchange[1] = (byte)N;
Array.Copy(Psk.Identity, 0, ClientKeyExchange, 2, N);
Endpoint.SendHandshake(HandshakeType.client_key_exchange, ClientKeyExchange, true, true, State);
// RFC 5246, §7.1, Change Cipher Spec Protocol:
Endpoint.SendRecord(ContentType.change_cipher_spec, new byte[] { 1 }, true, true, State);
Endpoint.ChangeCipherSpec(State, true);
this.SendFinished(Endpoint, State, true);
}
}
/// <summary>
/// Finishes the handshake.
/// </summary>
/// <param name="Endpoint">Endpoint.</param>
/// <param name="State">Endpoint state.</param>
/// <param name="Resendable">If flight of records is resendable.</param>
public virtual void SendFinished(DtlsEndpoint Endpoint, EndpointState State, bool Resendable)
{
if (State.masterSecret == null)
{
Endpoint.SendAlert(AlertLevel.fatal, AlertDescription.handshake_failure, State);
}
else
{
string Label;
byte[] HandshakeHash;
byte[] VerifyData;
if (State.isClient)
{
State.clientFinished = true;
Label = "client finished";
State.CalcClientHandshakeHash();
HandshakeHash = State.clientHandshakeHash;
}
else
{
State.serverFinished = true;
Label = "server finished";
State.CalcServerHandshakeHash();
HandshakeHash = State.serverHandshakeHash;
}
VerifyData = this.PRF(State.masterSecret, Label, HandshakeHash, 12);
Endpoint.SendHandshake(HandshakeType.finished, VerifyData, false, Resendable, State);
if (State.clientFinished && State.serverFinished)
{
Endpoint.HandshakeSuccess(State);
}
}
}
/// <summary>
/// Sends the Server Key Exchange message flight.
/// </summary>
/// <param name="Endpoint">Endpoint.</param>
/// <param name="State">Endpoint state.</param>
public override void SendServerKeyExchange(DtlsEndpoint Endpoint, EndpointState State)
{
Endpoint.SendHandshake(HandshakeType.server_hello_done, new byte[0], false, true, State);
}