NNostr

A Nostr Relay and Client written in C#

Client

Installation

dotnet add package NNostr.Client

Usage

1.) Initiate a new client

var client = new NostrClient(new Uri("wss://your-relay-url.com"));

2.) Connect to the relay

_ = client.Connect();

3.) Wait for the connection to be established

await client.WaitUntilConnected();

4.) Listen in for events

void OnClientOnEventsReceived(object sender, (string subscriptionId, NostrEvent[] events) args)
    {
        if (args.subscriptionId == "my-subscription-id")
        {
            foreach (var nostrEvent in args.events)
            {
                Console.WriteLine(nostrEvent.Content);
            }
        }
    }
client.EventsReceived += OnClientOnEventsReceived;

5.) Subscribe to events

//subscribe to all kind 1 events under the subscription id of "my-subscription-id"
client.CreateSubscription("my-subscription-id", new []
        {
            new NostrSubscriptionFilter()
            {
                Kinds = new []{1}
            }
})

6.) Send events

// create a private key:
var key = ECPrivKey.Create(RandomUtils.GetBytes(32));
// or else load a private key from a hex string
key = Context.Instance.CreateECPrivKey(Convert.FromHexString("7f4c11a9742721d66e40e321ca50b682c27f7422190c14a187525e69e604836a"));
// or load from an nsec string
key = "nsec1vl029mgpspedva04g90vltkh6fvh240zqtv9k0t9af8935ke9laqsnlfe5".FromNIP19Nsec();

// create a new event
var newEvent = new NostrEvent()
{
    Kind = 1,
    Content = "Hello World!"
};
// sign the event
await newEvent.ComputeIdAndSignAsync(key);
// send the event
await client.SendEventsAndWaitUntilReceived(new[] {evt}, CancellationToken.None);

Relay

• Install BTCPay Server through docker deployment https://docs.btcpayserver.org/Docker/#full-installation-for-technical-users
• run the following ssh commands

cd btcpayserver-docker
BTCPAYGEN_ADDITIONAL_FRAGMENTS="$BTCPAYGEN_ADDITIONAL_FRAGMENTS;opt-add-nostr-relay"
. ./btcpay-setup.sh -i

• your relay will be available at your btcpay url /nostr

Alternatively, you can configure a docker compose with the following service definition (it is missing nginx, ssl, postgres)

services:
  nnostr-relay:
    restart: unless-stopped
    image: kukks/nnostr-relay:v0.0.10-1
    container_name: nnostr-relay
    environment:
      NOSTR_CONNECTIONSTRINGS__RelayDatabase: User ID=postgres;Host=postgres;Port=5432;Database=nnostr
      ASPNETCORE_URLS: "http://0.0.0.0:80"
    links:
      - postgres
      - btcpayserver
    volumes:
      - "nnostr_datadir:/datadir"
volumes:
  nnostr_datadir:

Alternatively, you can go to /Relay, configure appsettings.json and dotnet run ( you need dotnet runtime installed)

Configure the relay

The relay is now running, great! DO NOT SHARE THE URL JUST YET! As there is no UI, one must first connect to the relay using a nostr client, and wait for a Notice event from the relay, that states that the relay is not yet configured and a temporary nostr private key has been created that you can use to configure. Simply login using that key, send a DM to yourself with the message /admin config to get the confougration options, and then send it back with /admin update {CONFIG}. Please note that the admin key (AdminKey) MUST be hex format, not nsec.

The BTCPay Server integration uses the BTCPay Server Greenfield API. You can generate a new API key by going to Account => API Keys, and the only permissions needed are CanViewInvoices and CanCreateInvoice.The mandatory ones for payments are BTCPayServerUri, BTCPayServerApiKey, and BTCPayServerStoreId.

Optionally, you can configure BTCPayServer to send a webhook (Store-Settings->Webhooks) to your relay url.com/nostr/btcpay/webhook for the specific event of An invoice has been settled. You are highly recommended to also configure a secret and then to configure it in the relay with BTCPayServerWebhookSecret configuration to reduce spam attacks.

Payment options

The relay allows you to charge a fee per event if wanted using the EventCost configuration. This is always in sats. You may also configure the relay to make the cost of an event dynamic, to charge based on the size of the event (1byte = eventcost) by setting EventCostPerByte to true.

You can charge pubkeys to be whitelisted on the server by setting PubKeyCost to the number of sats to charge.

Commands

As an admin (the key saved in AdminKey), you can DM yourself with the commands /admin update {config}, /admin factory-reset, /admin config

Any user can send a DM to the admin's public key, with the commands /topup and /balance.