go-nostr

A set of useful things for Nostr Protocol implementations.

Install go-nostr:

go get github.com/nbd-wtf/go-nostr

Generating a key

package main

import (
    "fmt"

    "github.com/nbd-wtf/go-nostr"
    "github.com/nbd-wtf/go-nostr/nip19"
)

func main() {
    sk := nostr.GeneratePrivateKey()
    pk, _ := nostr.GetPublicKey(sk)
    nsec, _ := nip19.EncodePrivateKey(sk)
    npub, _ := nip19.EncodePublicKey(pk)

    fmt.Println("sk:", sk)
    fmt.Println("pk:", pk)
    fmt.Println(nsec)
    fmt.Println(npub)
}

Subscribing to a single relay

ctx := context.Background()
relay, err := nostr.RelayConnect(ctx, "wss://nostr.zebedee.cloud")
if err != nil {
	panic(err)
}

npub := "npub1422a7ws4yul24p0pf7cacn7cghqkutdnm35z075vy68ggqpqjcyswn8ekc"

var filters nostr.Filters
if _, v, err := nip19.Decode(npub); err == nil {
	pub := v.(string)
	filters = []nostr.Filter{{
		Kinds:   []int{nostr.KindTextNote},
		Authors: []string{pub},
		Limit:   1,
	}}
} else {
	panic(err)
}

ctx, cancel := context.WithTimeout(ctx, 3*time.Second)
defer cancel()

sub, err := relay.Subscribe(ctx, filters)
if err != nil {
	panic(err)
}

for ev := range sub.Events {
	// handle returned event.
	// channel will stay open until the ctx is cancelled (in this case, context timeout)
	fmt.Println(ev.ID)
}

Publishing to two relays

sk := nostr.GeneratePrivateKey()
pub, _ := nostr.GetPublicKey(sk)

ev := nostr.Event{
	PubKey:    pub,
	CreatedAt: nostr.Now(),
	Kind:      nostr.KindTextNote,
	Tags:      nil,
	Content:   "Hello World!",
}

// calling Sign sets the event ID field and the event Sig field
ev.Sign(sk)

// publish the event to two relays
ctx := context.Background()
for _, url := range []string{"wss://nostr.zebedee.cloud", "wss://nostr-pub.wellorder.net"} {
	relay, err := nostr.RelayConnect(ctx, url)
	if err != nil {
		fmt.Println(err)
		continue
	}
	_, err = relay.Publish(ctx, ev)
	if err != nil {
		fmt.Println(err)
		continue
	}

	fmt.Printf("published to %s\n", url)
}

Authenticating with NIP-42

For this section, the user needs access to a relay implementing NIP-42. E.g., https://github.com/fiatjaf/relayer with a relay implementing the relayer.Auther interface.

func main() {
	url := "ws://localhost:7447"

	sk := nostr.GeneratePrivateKey()

	relay, err := nostr.RelayConnect(context.Background(), url,
        nostr.WithAuthHandler(func(ctx context.Context, authEvent *Event) (ok bool) {
            authEvent.Sign(sk)
        }),
    )
	if err != nil {
		panic(err)
	}
}

Example script

go run example/example.go

Warning: risk of goroutine bloat

Remember to cancel subscriptions, either by calling .Unsub() on them or ensuring their context.Context will be canceled at some point. If you don't do that they will keep creating a new goroutine for every new event that arrives and if you have stopped listening on the sub.Events channel that will cause chaos and doom in your program.

isaqueveras / go-nostr