KNX Secure explained simply – fundamentals, benefits and implementation

The standard for encrypted building automation – legally compliant, practical and future-proof

Modern buildings combine comfort, efficiency and sustainability in intelligent ways – using systems that rely on digital communication. As a result, the demands placed on communication security are increasing.

KNX Secure extends the globally established KNX standard with professional encryption and authentication mechanisms – making building automation fit for both current and future requirements.

On this page, you'll learn how KNX Secure works, the practical benefits it offers, and why legal and regulatory frameworks already make it a relevant topic today.

Enhanced Security for a Proven Standard

What is KNX Secure?

KNX Secure is a security extension of the well-established KNX standard for building automation. Originally, KNX was designed for physically closed systems – at a time when cyber risks were not a major concern. But with increasing connectivity, IP communication and remote access, it soon became clear: traditional telegrams transmitted in plain text needed protection.

The KNX Association introduced KNX Secure in 2017 as an official addition to the standard. The aim was to address growing requirements for data protection, integrity and access control in modern buildings – in a way that complies with international norms.

The technology brings robust encryption and authentication to the KNX ecosystem, based on the internationally recognised AES-128 algorithm (ISO/IEC 18033-3). It protects not only data transmission, but also the project structure and device configuration. KNX Secure is officially certified according to EN ISO 22510 and meets high standards for data privacy and IT security.

Operating principle

How does KNX Secure work?

KNX Secure is based on two complementary security mechanisms: KNX IP Secure, which encrypts communication over IP networks, and KNX Data Secure, which protects data directly on the bus line. Both approaches ensure secure communication within a KNX system by means of encryption and authentication.

KNX IP Secure adds full encryption and authentication to IP-based communication. Telegrams exchanged between routers, visualisation systems or interfaces are protected from tampering and interception – even when transmitted via external networks.
KNX Data Secure, on the other hand, encrypts user data directly on the bus line (Twisted Pair) or during wireless communication (KNX RF). Switching commands, setpoints and sensor values are thus protected against unauthorised access and manipulation – even within the building.

The two mechanisms can be used independently or in combination. They affect both the device configuration and project structure – making the ETS project file the central security anchor. Only those with access to the full project structure and cryptographic keys can modify or expand a system.

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Practical Impact

How does KNX Secure affect projects?

KNX Secure not only enhances technical security – it also changes how KNX projects are managed and implemented. Project access, documentation and commissioning processes must be carefully secured.

The introduction of KNX Secure marks a fundamental shift in project handling. Every Secure-capable device is supplied with a KNX Secure certificate, which includes the FDSK (Factory Default Setup Key). This key is imported during commissioning via ETS and forms the basis for encrypted communication within the project.

Commissioning is carried out in encrypted form, and communication is clearly defined – only participants with the correct key can access specific group addresses. If the ETS project file or associated keyring is lost, the system can no longer be maintained or expanded – recovery is not possible due to the encryption. Without access to the project file or the cryptographic keys (e.g. the FDSK stored in the keyring), no further changes can be made. This approach is deliberately strict and strengthens security on both a technical and organisational level.

For planners and system integrators, this means: clean documentation, a clear project structure and secure backup strategies are essential. But for those familiar with the system, the result is a high degree of planning reliability and significantly improved project security.

New Security Requirements

Where is KNX Secure mandatory – and what does it mean for your projects?

KNX Secure is no longer just a future topic – it is a direct response to growing security expectations that are increasingly shaping building automation. In several countries, including Germany and across the EU, regulations are placing greater responsibility on smart building systems when it comes to data protection, access control and system integrity.

In practice, this affects scenarios such as:

Schools, with publicly accessible control points
Healthcare and care facilities, handling personal data
Hotels and multi-dwelling buildings, with shared control systems and internet access
Existing buildings with remote maintenance, for example using cloud-based visualisation tools

KNX Secure provides the appropriate technical response: encrypted communication, strong authentication, and protection at both device and project level – certified and fully integrated into ETS. Those planning or upgrading building automation systems today should take these requirements into account at an early stage – before they become a barrier to implementation.

Note: Specific legal and regulatory requirements vary between countries. Please refer to national standards and data protection regulations applicable in your region.

European and National Regulations

Which legal frameworks make KNX Secure relevant?

Various European and national regulations are increasing the cybersecurity requirements for building automation. KNX Secure helps meet these demands in a technically sound and standard-compliant way – supporting, for example, NIS 2, the GDPR or the Cyber Resilience Act.

It's not just the technology that is evolving – the regulatory landscape is also changing rapidly. More and more legal frameworks call for a high level of cybersecurity in buildings. KNX Secure is not a cure-all, but it provides a key technical foundation for meeting these requirements in real-world applications.

Some of the most important regulatory instruments include:

EU NIS 2 Directive
Requires operators of critical infrastructure to implement extensive technical and organisational security measures – including those related to building automation.
GDPR (General Data Protection Regulation)
Where personal building data is processed – such as presence detection, indoor climate or access data – transmission must be protected against unauthorised access.
Cyber Resilience Act (CRA)
Establishes uniform cybersecurity requirements across the EU for manufacturers of connected products. This also applies to KNX components – making security mechanisms like KNX Secure a prerequisite for market approval.
IT Security Act 2.0 (Germany)
Expands the obligations for critical infrastructure operators and defines mandatory minimum standards for IT security – including in building-related systems.

KNX Secure can support structured, transparent compliance with these regulations – especially when combined with secure commissioning, thorough project documentation and professional key management.

Note: The legal relevance and implementation of these requirements may vary by country. Please consult applicable national or regional legislation.

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Backwards-Compatible – with Limitations

Can KNX Secure be retrofitted?

KNX Secure is generally backwards-compatible: Secure-capable devices can be integrated into existing KNX installations – even alongside conventional components. However, full protection is only achieved when all participants within a given communication structure – such as a line or segment – support the Secure standard.

In retrofit scenarios, this means Secure-capable devices can be introduced gradually, for example, when replacing individual actuators, sensors or line segments. These devices can also operate in a so-called “non-secure mode” – without encryption – for as long as legacy devices remain in the system.

It is also possible to selectively encrypt specific group addresses in order to protect security-critical functions early on. This creates a smooth migration path, enabling existing projects to gradually reach a higher level of security – without the need for complete system replacement.

One key consideration: Security only works effectively within homogeneous groups. As soon as a line or segment contains a mixture of Secure and non-Secure devices, vulnerabilities can arise. That’s why forward-looking project planning is essential.

Another important aspect: ETS becomes a security-critical element. Without access to the project file and the cryptographic keys it contains (e.g. FDSKs), no changes can be made. This adds protection – but also calls for professional project management and regular backups.

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Conclusion

Why KNX Secure is becoming the new standard

Modern building automation can no longer ignore cybersecurity. KNX Secure is the recognised technical standard for implementing encrypted communication, access control and project-level security – in a way that is both compliant and practical.

With KNX IP Secure and KNX Data Secure, the system protects not only the transmission of telegrams but also the integrity of entire projects – certified according to international standards such as EN ISO 22510. KNX Secure thus meets many of the requirements introduced by regulations such as NIS 2, the GDPR, and the Cyber Resilience Act.

For professionals involved in planning and integration, this means:

Planners should consider KNX Secure early on in security-critical projects – for example, in schools, hospitals or public buildings.
System integrators can enhance project quality with secure commissioning processes – building trust with clients and facility operators. A professional backup and key management strategy – including secure copies of ETS project files and KNX Secure certificates – is a critical success factor.
Operators and technology partners can actively prepare their clients for evolving security requirements – and offer appropriate solutions before legal obligations take effect.

Those who invest in KNX Secure today gain a clear advantage – technically, legally and economically.

Author: Elsner Elektronik Editorial Team | Last updated: 07/2025

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