}
    }

    /**
     * Get the current version of a session key
     *
     * @param sessionId the session ID
     * @return the key version, or 0 if not versioned
     */
    public int getKeyVersion(String sessionId) {
        return keyVersions.getOrDefault(sessionId, 0);
    }

    /**
     * Get key age in milliseconds
     *
     * @param sessionId the session ID

        // Initial version should be 0
        assertEquals(0, keyManager.getKeyVersion(sessionId), "Initial version should be 0");

        // Rotate key
        int newVersion = keyManager.rotateSessionKey(sessionId);
        assertEquals(1, newVersion, "New version should be 1");
        assertEquals(1, keyManager.getKeyVersion(sessionId), "Key version should be updated");

        // Verify old key is archived