feat(api): /devices register + paseto v4 (middleware Bearer, bootstrap mobile du token)

backend/pkg/auth/auth.go

@@ -0,0 +1,49 @@
+package auth
+
+import (
+	"crypto/sha256"
+	"errors"
+	"time"
+
+	"aidanwoods.dev/go-paseto"
+)
+
+const TokenTTL = 90 * 24 * time.Hour
+
+var ErrInvalidToken = errors.New("invalid token")
+
+// Manager issues and verifies paseto v4-local bearer tokens bound to a device_id.
+type Manager struct {
+	key paseto.V4SymmetricKey
+}
+
+func NewManager(secret string) (*Manager, error) {
+	sum := sha256.Sum256([]byte(secret))
+	key, err := paseto.V4SymmetricKeyFromBytes(sum[:])
+	if err != nil {
+		return nil, err
+	}
+	return &Manager{key: key}, nil
+}
+
+func (m *Manager) Issue(deviceID string) (string, error) {
+	now := time.Now()
+	token := paseto.NewToken()
+	token.SetIssuedAt(now)
+	token.SetNotBefore(now)
+	token.SetExpiration(now.Add(TokenTTL))
+	token.SetSubject(deviceID)
+	return token.V4Encrypt(m.key, nil), nil
+}
+
+func (m *Manager) Verify(signed string) (string, error) {
+	parsed, err := paseto.NewParserForValidNow().ParseV4Local(m.key, signed, nil)
+	if err != nil {
+		return "", ErrInvalidToken
+	}
+	subject, err := parsed.GetSubject()
+	if err != nil {
+		return "", ErrInvalidToken
+	}
+	return subject, nil
+}