Added jwt signer

protocol/meshcore/crypto/jwt/jwt.go

@@ -0,0 +1,78 @@
+// Package jwt implements JSON Web Tokens (JWT) using Meshcore Ed25519 keys
+package jwt
+
+import (
+	"fmt"
+
+	"git.maze.io/go/ham/protocol/meshcore/crypto"
+
+	"github.com/golang-jwt/jwt/v5"
+)
+
+var SigningMethod jwt.SigningMethod
+
+func init() {
+	SigningMethod = new(SigningMethodEd25519)
+}
+
+type SigningMethodEd25519 struct{}
+
+func (m *SigningMethodEd25519) Alg() string {
+	return "Ed25519"
+}
+
+func (m *SigningMethodEd25519) Sign(signingString string, key any) ([]byte, error) {
+	var (
+		privateKey *crypto.PrivateKey
+		err        error
+	)
+	switch key := key.(type) {
+	case *crypto.PrivateKey:
+		privateKey = key
+	case []byte:
+		switch len(key) {
+		case crypto.SeedSize:
+			if privateKey, err = crypto.NewPrivateKeyFromSeed(key); err != nil {
+				return nil, err
+			}
+		default:
+			if privateKey, err = crypto.NewPrivateKey(key); err != nil {
+				return nil, err
+			}
+		}
+	default:
+		return nil, fmt.Errorf("jwt: invalid Ed25519 private key %T", key)
+	}
+
+	return crypto.Sign(privateKey, []byte(signingString)), nil
+}
+
+func (m *SigningMethodEd25519) Verify(signingString string, sig []byte, key any) error {
+	var (
+		publicKey *crypto.PublicKey
+		err       error
+	)
+	switch key := key.(type) {
+	case *crypto.PublicKey:
+		publicKey = key
+	case crypto.PublicKey:
+		publicKey = &key
+	case *crypto.PrivateKey:
+		if publicKey, err = crypto.NewPublicKey(key.PublicKey()); err != nil {
+			return err
+		}
+	case []byte:
+		if publicKey, err = crypto.NewPublicKey(key); err != nil {
+			return err
+		}
+	case string:
+		if publicKey, err = crypto.DecodePublicKey(key); err != nil {
+			return err
+		}
+	default:
+		return fmt.Errorf("jwt: invalid Ed25519 public key %T", key)
+	}
+	return crypto.Verify(publicKey, []byte(signingString), sig)
+}
+
+var _ jwt.SigningMethod = (*SigningMethodEd25519)(nil)