/// <summary>
/// Validates the server's key by asking it to authenticate to the client.
/// </summary>
private async Task VerifyServer()
{
var token = GpgAuthToken.NewToken();
var encryptedToken = await _pgp.EncryptStringAsync(token.Token, _serverKey);
var auth = new Dictionary <string, dynamic>
{
{ "gpg_auth", new Dictionary <string, dynamic>
{
{ "keyid", _clientKey.Fingerprint },
{ "server_verify_token", encryptedToken }
} }
};
var result = await _session.Post(URL_LOGIN, auth).SendAsync();
result.ThrowIfFailed();
GpgAuthHeaders.Validate(result.Response.Headers, GpgAuthState.VerifyServer);
var verifyToken = new GpgAuthToken(result.Response.Headers.GetValue("X-GPGAuth-Verify-Response"));
if (verifyToken.Token != token.Token)
{
throw new Exception("The server failed to prove it can use the advertised OpenPGP key.");
}
}