go-nostr/README.md

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go-nostr
========

A set of useful things for [Nostr Protocol](https://github.com/nostr-protocol/nostr) implementations.

<a href="https://godoc.org/github.com/nbd-wtf/go-nostr"><img src="https://img.shields.io/badge/api-reference-blue.svg?style=flat-square" alt="GoDoc"></a>

### Generating a key

``` go
sk, _ := nostr.GenerateKey()
pk, _ := nostr.GetPublicKey(sk)
nsec, _ := nip19.EncodePrivateKey(sk)
npub, _ := nip19.EncodePublicKey(pk)

fmt.Println("sk:", sk)
fmt.Println("pk:", nostr.GetPublicKey(sk))
fmt.Println(nsec)
fmt.Println(npub)
```

### Subscribing to a single relay

``` go
relay, err := nostr.RelayConnect(context.Background(), "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{1},
		Authors: []string{pub},
		Limit:   1,
	}}
} else {
	panic(err)
}

ctx, cancel := context.WithCancel(context.Background())
sub := relay.Subscribe(ctx, filters)

go func() {
	<-sub.EndOfStoredEvents
	// handle end of stored events (EOSE, see NIP-15)
}()

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

### Publishing to two relays

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

ev := nostr.Event{
	PubKey:    pub,
	CreatedAt: time.Now(),
	Kind:      1,
	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
for _, url := range []string{"wss://nostr.zebedee.cloud", "wss://nostr-pub.wellorder.net"} {
	relay, e := nostr.RelayConnect(context.Background(), url)
	if e != nil {
		fmt.Println(e)
		continue
	}
	fmt.Println("published to ", url, relay.Publish(context.Background(), ev))
}
```

### 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.

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

	// Once the connection is initiated the server will send "AUTH" with the challenge string.
	relay, err := nostr.RelayConnect(context.Background(), url)
	if err != nil {
		panic(err)
	}

	// Initialize test user.
	sk := nostr.GeneratePrivateKey()
	pub, _ := nostr.GetPublicKey(sk)
	npub, _ := nip19.EncodePublicKey(pub)

	// Relay.Challenges channel will receive the "AUTH" command.
	challenge := <-relay.Challenges

	// Create the auth event to send back.
	// The user will be authenticated as pub.
	event := nip42.CreateUnsignedAuthEvent(challenge, pub, url)
	event.Sign(sk)

	// Set-up context with 3 second time out.
	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
	defer cancel()

	// Send the event by calling relay.Auth.
	// Returned status is either success, fail, or sent (if no reply given in the 3 second timeout).
	auth_status := relay.Auth(ctx, event)

	fmt.Printf("authenticated as %s: %s\n", npub, auth_status)
}
```

### Example script

```
go run example/example.go
```