mirror of
https://github.com/nbd-wtf/go-nostr.git
synced 2025-09-17 19:13:56 +02:00
nip-46 signer flow helpers.
This commit is contained in:
fiatjaf
259
nip46/signer.go
Normal file
259
nip46/signer.go
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@@ -0,0 +1,259 @@
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package nip46
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import (
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"encoding/hex"
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"encoding/json"
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"fmt"
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"github.com/mailru/easyjson"
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"github.com/nbd-wtf/go-nostr"
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"github.com/nbd-wtf/go-nostr/nip04"
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"golang.org/x/exp/slices"
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)
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type Request struct {
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ID string `json:"id"`
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Method string `json:"method"`
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Params []any `json:"params"`
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}
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type Response struct {
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ID string `json:"id"`
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Error string `json:"error,omitempty"`
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Result any `json:"result,omitempty"`
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}
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type Session struct {
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SharedKey []byte
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}
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func (s Session) ParseRequest(event *nostr.Event) (Request, error) {
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var req Request
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plain, err := nip04.Decrypt(event.Content, s.SharedKey)
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if err != nil {
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return req, fmt.Errorf("failed to decrypt event from %s: %w", event.PubKey, err)
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}
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err = json.Unmarshal([]byte(plain), &req)
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return req, err
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}
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func (s Session) MakeResultResponse(id string, result any) (nostr.Event, error) {
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evt := nostr.Event{
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CreatedAt: nostr.Now(),
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Kind: nostr.KindNostrConnect,
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Tags: nostr.Tags{},
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}
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data, err := json.Marshal(result)
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if err != nil {
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return evt, fmt.Errorf("failed to encode result to json: %w", err)
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}
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ciphertext, err := nip04.Encrypt(string(data), s.SharedKey)
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if err != nil {
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return evt, fmt.Errorf("failed to encrypt result: %w", err)
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}
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evt.Content = ciphertext
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err = evt.Sign(hex.EncodeToString(s.SharedKey))
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if err != nil {
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return evt, err
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}
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return evt, nil
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}
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func (s Session) MakeErrorResponse(id string, err error) (nostr.Event, error) {
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evt := nostr.Event{
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CreatedAt: nostr.Now(),
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Kind: nostr.KindNostrConnect,
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Tags: nostr.Tags{},
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}
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resp, _ := json.Marshal(Response{
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ID: id,
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Error: err.Error(),
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})
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ciphertext, err := nip04.Encrypt(string(resp), s.SharedKey)
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if err != nil {
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return evt, fmt.Errorf("failed to encrypt result: %w", err)
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}
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evt.Content = ciphertext
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err = evt.Sign(hex.EncodeToString(s.SharedKey))
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if err != nil {
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return evt, err
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}
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return evt, nil
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}
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type Pool struct {
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secretKey string
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sessionKeys []string
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sessions []Session
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RelaysToAdvertise map[string]relayReadWrite
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}
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type relayReadWrite struct {
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Read bool `json:"read"`
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Write bool `json:"write"`
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}
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func NewPool(secretKey string) Pool {
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return Pool{secretKey: secretKey}
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}
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func (p *Pool) AddRelay(url string, read bool, write bool) {
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p.RelaysToAdvertise[url] = relayReadWrite{read, write}
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}
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func (p *Pool) GetSession(clientPubkey string) (Session, error) {
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idx, exists := slices.BinarySearch(p.sessionKeys, clientPubkey)
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if exists {
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return p.sessions[idx], nil
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}
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shared, err := nip04.ComputeSharedSecret(clientPubkey, p.secretKey)
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if err != nil {
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return Session{}, fmt.Errorf("failed to compute shared secret: %w", err)
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}
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session := Session{
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SharedKey: shared,
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}
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// add to pool
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p.sessionKeys = append(p.sessionKeys, "") // bogus append just to increase the capacity
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p.sessions = append(p.sessions, Session{})
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copy(p.sessionKeys[idx+1:], p.sessionKeys[idx:])
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copy(p.sessions[idx+1:], p.sessions[idx:])
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p.sessionKeys[idx] = clientPubkey
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p.sessions[idx] = session
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return session, nil
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}
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func (p *Pool) HandleRequest(event *nostr.Event) (req Request, resp nostr.Event, err error) {
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if event.Kind != nostr.KindNostrConnect {
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return req, resp, fmt.Errorf("event kind is %d, but we expected %d",
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event.Kind, nostr.KindNostrConnect)
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}
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session, err := p.GetSession(event.PubKey)
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if err != nil {
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return req, resp, err
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}
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req, err = session.ParseRequest(event)
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if err != nil {
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return req, resp, fmt.Errorf("error parsing request: %w", err)
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}
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var result any
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var resultErr error
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switch req.Method {
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case "connect":
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result = map[string]any{}
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case "get_public_key":
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pubkey, err := nostr.GetPublicKey(p.secretKey)
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if err != nil {
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resultErr = fmt.Errorf("failed to derive public key: %w", err)
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goto end
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} else {
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result = pubkey
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}
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case "sign_event":
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if len(req.Params) != 1 {
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resultErr = fmt.Errorf("wrong number of arguments to 'sign_event'")
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goto end
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}
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jevt, err := json.Marshal(req.Params[0])
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if err != nil {
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resultErr = fmt.Errorf("failed to decode event/1: %w", err)
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goto end
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}
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evt := nostr.Event{}
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err = easyjson.Unmarshal(jevt, &evt)
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if err != nil {
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resultErr = fmt.Errorf("failed to decode event/2: %w", err)
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goto end
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}
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err = evt.Sign(p.secretKey)
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if err != nil {
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resultErr = fmt.Errorf("failed to sign event: %w", err)
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goto end
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}
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result = evt
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case "get_relays":
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result = p.RelaysToAdvertise
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case "nip04_encrypt":
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if len(req.Params) != 2 {
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resultErr = fmt.Errorf("wrong number of arguments to 'nip04_encrypt'")
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goto end
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}
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thirdPartyPubkey, ok := req.Params[0].(string)
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if !ok || !nostr.IsValidPublicKeyHex(thirdPartyPubkey) {
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resultErr = fmt.Errorf("first argument to 'nip04_encrypt' is not a pubkey string")
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goto end
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}
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plaintext, ok := req.Params[1].(string)
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if !ok {
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resultErr = fmt.Errorf("second argument to 'nip04_encrypt' is not a string")
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goto end
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}
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sharedSecret, err := nip04.ComputeSharedSecret(thirdPartyPubkey, p.secretKey)
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if err != nil {
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resultErr = fmt.Errorf("failed to compute shared secret: %w", err)
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goto end
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}
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ciphertext, err := nip04.Encrypt(plaintext, sharedSecret)
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if err != nil {
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resultErr = fmt.Errorf("failed to encrypt: %w", err)
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goto end
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}
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result = ciphertext
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case "nip04_decrypt":
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if len(req.Params) != 2 {
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resultErr = fmt.Errorf("wrong number of arguments to 'nip04_decrypt'")
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goto end
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}
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thirdPartyPubkey, ok := req.Params[0].(string)
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if !ok || !nostr.IsValidPublicKeyHex(thirdPartyPubkey) {
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resultErr = fmt.Errorf("first argument to 'nip04_decrypt' is not a pubkey string")
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goto end
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}
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ciphertext, ok := req.Params[1].(string)
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if !ok {
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resultErr = fmt.Errorf("second argument to 'nip04_decrypt' is not a string")
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goto end
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}
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sharedSecret, err := nip04.ComputeSharedSecret(thirdPartyPubkey, p.secretKey)
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if err != nil {
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resultErr = fmt.Errorf("failed to compute shared secret: %w", err)
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goto end
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}
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plaintext, err := nip04.Decrypt(ciphertext, sharedSecret)
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if err != nil {
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resultErr = fmt.Errorf("failed to encrypt: %w", err)
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goto end
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}
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result = plaintext
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default:
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return req, resp, fmt.Errorf("unknown method '%s'", req.Method)
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}
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end:
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if resultErr != nil {
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resp, err = session.MakeErrorResponse(req.ID, resultErr)
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} else if result != nil {
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resp, err = session.MakeResultResponse(req.ID, map[string]any{})
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}
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if err != nil {
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return req, resp, fmt.Errorf("failed to encrypt '%s' result", req.Method)
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}
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return req, resp, nil
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}
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