// Archive old key (keep last version for rollback)
            String archiveId = sessionId + ".v" + currentVersion;
            storeSessionKeyInternal(archiveId, currentKey, "AES");

            // Store new key
            storeSessionKeyInternal(sessionId, newKey, "AES");
            keyVersions.put(sessionId, newVersion);
            keyCreationTimes.put(sessionId, System.currentTimeMillis());