// Verify only recent versions are kept
        assertTrue(keyManager.hasSessionKey(sessionId + ".v4"), "Version 4 should exist");
        assertTrue(keyManager.hasSessionKey(sessionId + ".v3"), "Version 3 should exist");
        assertFalse(keyManager.hasSessionKey(sessionId + ".v2"), "Version 2 should be removed");
        assertFalse(keyManager.hasSessionKey(sessionId + ".v1"), "Version 1 should be removed");

        return sessionKeys.size();
    }

    /**
     * Check if a session key exists
     *
     * @param sessionId session identifier
     * @return true if key exists
     */
    public boolean hasSessionKey(String sessionId) {
        checkNotClosed();
        return sessionKeys.containsKey(sessionId) || (keyStore != null && keyStoreContainsKey(sessionId));
    }