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venfree/Wiki/KNX Secure – Encryption for the Bus

KNX Secure – Encryption for the Bus

KNX Secure is the security standard for KNX communication. It protects bus telegrams against eavesdropping and manipulation, both on IP networks (IP Secure) and on the TP cable (Data Security).

IP Secure and Data Security

KNX IP Secure encrypts KNXnet/IP connections (tunneling and routing) with AES-128-CBC and authentication. Protects communication on the LAN and over the internet.

KNX Data Security (TP Secure) encrypts telegrams directly on the TP bus with AES-128-CCM. Also protects against physical tapping of the bus cable. Both variants can be activated independently of each other.

Tool Key and Recommendation

In ETS 6, each project receives a random Project Tool Key. Without this key, a device cannot be reprogrammed, not even by someone with physical bus access. This prevents unauthorised reconfiguration.

KNX Secure is strongly recommended for all installations with IP access (remote programming, visualisation, Home Assistant connection). For pure TP installations without remote access in private buildings, it is optional but future-proof.

Key Facts

  • IP Secure: AES-128-CBC, protects KNXnet/IP
  • Data Security: AES-128-CCM, protects TP telegrams
  • Tool Key: prevents unauthorised reprogramming
  • Fully integrated from ETS 6
  • Never expose port 3671 to the internet without KNX Secure

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