Replace VNC JWT auth with a Noise_IK handshake bound to ACL-pushed pubkeys

client/ssh/server/executor_windows.go

@@ -200,8 +200,8 @@ func newLsaString(s string) lsaString {
 	}
 }
 
-// generateS4UUserToken creates a Windows token using S4U authentication.
-// This is the same approach OpenSSH for Windows uses for public key authentication.
+// generateS4UUserToken creates a Windows token using S4U authentication
+// This is the exact approach OpenSSH for Windows uses for public key authentication
 func generateS4UUserToken(logger *log.Entry, username, domain string) (windows.Handle, error) {
 	userCpn := buildUserCpn(username, domain)
 

client/ssh/server/server.go

@@ -551,7 +551,27 @@ func (s *Server) checkTokenAge(token *gojwt.Token, jwtConfig *JWTConfig) error {
 		maxTokenAge = DefaultJWTMaxTokenAge
 	}
 
-	return jwt.CheckTokenAge(token, time.Duration(maxTokenAge)*time.Second)
+	claims, ok := token.Claims.(gojwt.MapClaims)
+	if !ok {
+		userID := extractUserID(token)
+		return fmt.Errorf("token has invalid claims format (user=%s)", userID)
+	}
+
+	iat, ok := claims["iat"].(float64)
+	if !ok {
+		userID := extractUserID(token)
+		return fmt.Errorf("token missing iat claim (user=%s)", userID)
+	}
+
+	issuedAt := time.Unix(int64(iat), 0)
+	tokenAge := time.Since(issuedAt)
+	maxAge := time.Duration(maxTokenAge) * time.Second
+	if tokenAge > maxAge {
+		userID := getUserIDFromClaims(claims)
+		return fmt.Errorf("token expired for user=%s: age=%v, max=%v", userID, tokenAge, maxAge)
+	}
+
+	return nil
 }
 
 func (s *Server) extractAndValidateUser(token *gojwt.Token) (*auth.UserAuth, error) {
@@ -582,7 +602,27 @@ func (s *Server) hasSSHAccess(userAuth *auth.UserAuth) bool {
 }
 
 func extractUserID(token *gojwt.Token) string {
-	return jwt.UserIDFromToken(token)
+	if token == nil {
+		return "unknown"
+	}
+	claims, ok := token.Claims.(gojwt.MapClaims)
+	if !ok {
+		return "unknown"
+	}
+	return getUserIDFromClaims(claims)
+}
+
+func getUserIDFromClaims(claims gojwt.MapClaims) string {
+	if sub, ok := claims["sub"].(string); ok && sub != "" {
+		return sub
+	}
+	if userID, ok := claims["user_id"].(string); ok && userID != "" {
+		return userID
+	}
+	if email, ok := claims["email"].(string); ok && email != "" {
+		return email
+	}
+	return "unknown"
 }
 
 func (s *Server) parseTokenWithoutValidation(tokenString string) (map[string]interface{}, error) {