metrics.put("bytesEncryptedSinceLastRotation", bytesEncrypted.get());
        metrics.put("timeSinceLastRotation", System.currentTimeMillis() - encryptionStartTime);
        metrics.put("rotationBytesLimit", keyRotationBytesLimit);
        metrics.put("rotationTimeLimit", keyRotationTimeLimit);
        return metrics;
    }

    /**
     * Generate a unique nonce for encryption following SMB3 specification.