security solutions

A core issue that is often overlooked, the building automation system, also known as BAS in English, is a system whose intelligent upgrades are continuing to deepen. Its network security, especially its ability to resist future quantum computing attacks, has become an urgent issue. Post-quantum cryptography, also known as PQC in English, is a key technology to meet this challenge. It can ensure that key control systems such as HVAC, lighting, and security in buildings remain safe and trustworthy in the era of quantum computing. For BAS, deploying PQC is not only about defending against future threats, but also a necessary measure to deal with the current "capture now, decrypt later" attack strategy.

How post-quantum cryptography protects building automation systems from quantum attacks

Post-quantum cryptographic protection is achieved by replacing the mathematical basis of current encryption algorithms. The current BAS system relies extensively on traditional public key algorithms such as RSA for device authentication and communication encryption. However, the security of these algorithms will no longer exist in the face of quantum computers. Post-quantum cryptographic algorithms are based on mathematical problems that are difficult to solve by quantum computers, such as grid and encoding problems.

Within the specific scenario of BAS, this means that all communication links starting from the central server, to the field controller (DDC), to various sensors and actuators, their identity authentication and session key exchange processes must be upgraded using the PQC algorithm. For example, crucial instructions such as controlling the start and stop of chillers or reading access card swipe records must rely on quantum-resistant authentication to avoid being forged or eavesdropped. Such upgrades can resist the long-term threat of attackers intercepting currently encrypted data and waiting for future quantum computers to decrypt it when they mature, thereby ensuring the long-term confidentiality of building operation data.

What are the main challenges in migrating building automation systems to post-quantum cryptography?

When the BAS system migrates towards post-quantum cryptography, it will encounter unique complexity challenges. The primary challenge is the heterogeneity and long life cycle of the system. The BAS of buildings are often integrated by equipment from multiple brands and different ages, resulting in outdated and aging equipment. Its computing resources are limited, and it may be difficult to run new algorithms that require large computing or storage costs. At the same time, building systems are designed to be used for decades, far exceeding the iteration cycle of current encryption equipment, which makes "future proof" issues particularly important.

There are strict requirements for real-time performance and reliability. Related operations such as emergency stop and start of ventilation systems and linkage control of fire alarms have extremely high requirements for communication delay and system stability. Some post-quantum cryptographic algorithms are different from traditional algorithms in terms of signature generation, verification speed or communication bandwidth overhead, which may affect the real-time performance of the control loop. Therefore, the migration plan should undergo strict compatibility and stress testing to ensure that it will not affect the normal and safe operation of the building under any circumstances.

Why Building Automation Systems Need a Hybrid Encryption Transition Plan

For a system like BAS that has extremely high requirements for continuous operation, the risk of directly replacing the encryption algorithm is quite high. Therefore, adopting a hybrid encryption transition solution is currently recognized as a best practice in the industry. During the communication process, this solution uses both traditional algorithms (such as RSA) and a post-quantum algorithm (such as lattice-based -) to perform double signature or double key exchange.

The core advantage of doing it this way is that both smoothness and safety are equally important. During the transition period, even if potential loopholes in post-quantum algorithms are discovered, the system will still rely on traditional algorithms to maintain security; on the contrary, when the threats posed by quantum computers gradually approach, traditional algorithms will fail, and the post-quantum part can still provide protection. Such a mechanism with "double insurance" characteristics allows BAS operators to carry out deployment operations and verify PQC according to stages and devices without causing interruption to existing services, greatly reducing the risks faced by migration to a great extent. Cloud service providers such as Amazon AWS also implement similar strategies, with the goal of achieving a migration that is invisible to users.

How to choose the right post-quantum cryptographic algorithm for building automation systems

When selecting a PQC algorithm for BAS, you need to make a comprehensive and balanced decision on security, performance, and system constraints. At present, lattice-based algorithms, such as Kyber and Kyber, which are standardized by NIST, have become the first choice in many application scenarios because they have achieved a good balance between security and efficiency. They are suitable for very frequent key exchanges and command signing operations between controllers and servers in BAS.

However, for edge devices with extremely limited resources, such as wireless temperature and humidity sensors, it may be necessary to consider a more streamlined implementation, or a hash-based signature algorithm, such as +. Although the latter has a relatively large signature, the computing resources required are more controllable. The choice of algorithm is not single. A large BAS project needs to face three different levels, namely the central management layer, the regional control layer and the field equipment layer. Different algorithm configuration strategies must be formulated for these three levels. When synchronizing, be sure to give priority to those that have undergone strict standardization, such as NIST and IETF, and also provide algorithm libraries that resist side-channel attacks to deal with security threats in the actual physical environment.

What are the specific steps to implement post-quantum cryptography in building automation systems?

Carrying out PQC in BAS is a systematic project. It is recommended to follow the following steps. The first step is to conduct a comprehensive asset inventory and risk assessment. It is necessary to sort out all BAS equipment, communication protocols and current encryption usage in the network. It is also necessary to evaluate which control links, such as energy management and security alarms, are the most critical assets that need to be protected with priority.

The second step is to design a cryptographic agility architecture, which is at the core of a successful migration. This suggests that systems should be designed to dynamically replace encryption algorithms via software updates without hardware replacement and without service interruption. For BAS, this may mean reserving algorithm module slots in central management software or network gateways. Subsequently, in an independent test environment, integration tests were conducted on the candidate PQC algorithm and existing BAS protocols such as /IP and TCP to verify its functionality and performance impact. Finally, formulate a phased rollout plan, for example, starting with new projects or upgrading key systems, and then successively covering existing systems.

What profound impact will quantum computing have on building automation safety in the future?

As quantum computing matures, it will reshape the security paradigm of the entire BAS. Its most direct impact is that all current device certificates and digital signatures based on asymmetric cryptography will immediately lose their validity. This shows that unauthorized entities have the possibility of forging control instructions and can control lights, elevators and even power supplies at will, causing physical security problems and economic losses.

A more profound impact lies in the integration of security architecture. In the future, post-quantum cryptography may be combined with quantum key distribution and other technologies to provide key distribution services based on the laws of physics for occasions with ultra-high security requirements, such as key government buildings and financial data centers. At the same time, for In order to be able to deal with new attacks born from the combination of quantum computing and artificial intelligence, BAS's intrusion detection and abnormal behavior analysis systems also need to evolve simultaneously. Owners, system integrators, and security suppliers should start planning from now on and regard post-quantum security as a necessary attribute of the digital base of smart buildings.

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For those of you who are in the stage of planning or operating smart buildings, after knowing the urgency of quantum threats, have you already initiated a quantum security risk assessment for the building automation systems under your own name or management? What worries you most is the compatibility issues covered by existing equipment, or the risk of operational interruption that may occur in the middle of the migration process? Feel free to share your own views and challenges in the comment area.