well-goknown/vendor/github.com/nbd-wtf/go-nostr/event.go

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package nostr
import (
"crypto/sha256"
"encoding/hex"
"fmt"
"github.com/btcsuite/btcd/btcec/v2"
"github.com/btcsuite/btcd/btcec/v2/schnorr"
"github.com/mailru/easyjson"
)
type Event struct {
ID string
PubKey string
CreatedAt Timestamp
Kind int
Tags Tags
Content string
Sig string
// anything here will be mashed together with the main event object when serializing
extra map[string]any
}
// Event Stringer interface, just returns the raw JSON as a string.
func (evt Event) String() string {
j, _ := easyjson.Marshal(evt)
return string(j)
}
// GetID serializes and returns the event ID as a string.
func (evt *Event) GetID() string {
h := sha256.Sum256(evt.Serialize())
return hex.EncodeToString(h[:])
}
// CheckID checks if the implied ID matches the given ID
func (evt *Event) CheckID() bool {
ser := evt.Serialize()
h := sha256.Sum256(ser)
const hextable = "0123456789abcdef"
for i := 0; i < 32; i++ {
b := hextable[h[i]>>4]
if b != evt.ID[i*2] {
return false
}
b = hextable[h[i]&0x0f]
if b != evt.ID[i*2+1] {
return false
}
}
return true
}
// Serialize outputs a byte array that can be hashed/signed to identify/authenticate.
// JSON encoding as defined in RFC4627.
func (evt *Event) Serialize() []byte {
// the serialization process is just putting everything into a JSON array
// so the order is kept. See NIP-01
dst := make([]byte, 0)
// the header portion is easy to serialize
// [0,"pubkey",created_at,kind,[
dst = append(dst, []byte(
fmt.Sprintf(
"[0,\"%s\",%d,%d,",
evt.PubKey,
evt.CreatedAt,
evt.Kind,
))...)
// tags
dst = evt.Tags.marshalTo(dst)
dst = append(dst, ',')
// content needs to be escaped in general as it is user generated.
dst = escapeString(dst, evt.Content)
dst = append(dst, ']')
return dst
}
// CheckSignature checks if the signature is valid for the id
// (which is a hash of the serialized event content).
// returns an error if the signature itself is invalid.
func (evt Event) CheckSignature() (bool, error) {
// read and check pubkey
pk, err := hex.DecodeString(evt.PubKey)
if err != nil {
return false, fmt.Errorf("event pubkey '%s' is invalid hex: %w", evt.PubKey, err)
}
pubkey, err := schnorr.ParsePubKey(pk)
if err != nil {
return false, fmt.Errorf("event has invalid pubkey '%s': %w", evt.PubKey, err)
}
// read signature
s, err := hex.DecodeString(evt.Sig)
if err != nil {
return false, fmt.Errorf("signature '%s' is invalid hex: %w", evt.Sig, err)
}
sig, err := schnorr.ParseSignature(s)
if err != nil {
return false, fmt.Errorf("failed to parse signature: %w", err)
}
// check signature
hash := sha256.Sum256(evt.Serialize())
return sig.Verify(hash[:], pubkey), nil
}
// Sign signs an event with a given privateKey.
func (evt *Event) Sign(privateKey string, signOpts ...schnorr.SignOption) error {
s, err := hex.DecodeString(privateKey)
if err != nil {
return fmt.Errorf("Sign called with invalid private key '%s': %w", privateKey, err)
}
if evt.Tags == nil {
evt.Tags = make(Tags, 0)
}
sk, pk := btcec.PrivKeyFromBytes(s)
pkBytes := pk.SerializeCompressed()
evt.PubKey = hex.EncodeToString(pkBytes[1:])
h := sha256.Sum256(evt.Serialize())
sig, err := schnorr.Sign(sk, h[:], signOpts...)
if err != nil {
return err
}
evt.ID = hex.EncodeToString(h[:])
evt.Sig = hex.EncodeToString(sig.Serialize())
return nil
}