first commit

internal/nostr/keys.go

@@ -0,0 +1,72 @@
+package nostr
+
+import (
+	"encoding/hex"
+	"errors"
+	"strings"
+
+	gn "github.com/nbd-wtf/go-nostr"
+	"github.com/nbd-wtf/go-nostr/nip19"
+)
+
+var (
+	ErrInvalidPubkey = errors.New("invalid pubkey")
+	ErrInvalidNsec   = errors.New("invalid nsec")
+)
+
+// NormalizePubkey accepts npub bech32 or 64-char hex and returns lowercase hex.
+func NormalizePubkey(in string) (string, error) {
+	in = strings.TrimSpace(in)
+	if in == "" {
+		return "", ErrInvalidPubkey
+	}
+	if strings.HasPrefix(in, "npub1") {
+		prefix, data, err := nip19.Decode(in)
+		if err != nil {
+			return "", ErrInvalidPubkey
+		}
+		if prefix != "npub" {
+			return "", ErrInvalidPubkey
+		}
+		s, ok := data.(string)
+		if !ok {
+			return "", ErrInvalidPubkey
+		}
+		return strings.ToLower(s), nil
+	}
+	if len(in) != 64 {
+		return "", ErrInvalidPubkey
+	}
+	if _, err := hex.DecodeString(in); err != nil {
+		return "", ErrInvalidPubkey
+	}
+	if !gn.IsValidPublicKey(in) {
+		return "", ErrInvalidPubkey
+	}
+	return strings.ToLower(in), nil
+}
+
+// HexToNpub converts hex pubkey to npub bech32. Empty string on error.
+func HexToNpub(hexpk string) string {
+	npub, err := nip19.EncodePublicKey(hexpk)
+	if err != nil {
+		return ""
+	}
+	return npub
+}
+
+// NsecToHex decodes nsec1... to hex private key.
+func NsecToHex(nsec string) (string, error) {
+	prefix, data, err := nip19.Decode(strings.TrimSpace(nsec))
+	if err != nil {
+		return "", ErrInvalidNsec
+	}
+	if prefix != "nsec" {
+		return "", ErrInvalidNsec
+	}
+	s, ok := data.(string)
+	if !ok {
+		return "", ErrInvalidNsec
+	}
+	return strings.ToLower(s), nil
+}