RE: How to modify Matter device’s discriminator and setup PIN code without configuring factorydata?

Marte Myrvold — Thu, 30 Jan 2025 14:21:42 GMT

Hi Bhavya,

You can change the descriminator with CONFIG_CHIP_DEVICE_DISCRIMINATOR in prj.conf. As for the PIN code, you can change it using CONFIG_CHIP_DEVICE_SPAKE2_PASSCODE, but you will also have to generate a new SPAKE2+ verifier for the new passcode and set CONFIG_CHIP_FACTORY_DATA_GENERATE_SPAKE2_VERIFIER=n.

The SPAKE2+ verifier can be generated with the SPAKE2+ Python Tool using the passcode, SPAKE2+ salt, and iteration count. The simplest is to use the default SPAKE2+ salt (U1BBS0UyUCBLZXkgU2FsdA==) and iteration count (1000). Here is an example where I use the default salt and iteration count but a different passcode:

./spake2p.py gen-verifier -p 20372039 -s U1BBS0UyUCBLZXkgU2FsdA== -i 1000

This results in the verifier kLXow6J5EYWRa3aO71DkTG5qMtkn5PfwwXhOixGa2zEEDEDGlKfe7mEBAg6b3CTx++XPKapVRxnuWs6r6O90+7aDXjlDytFVwlS+PVpSY3dQTmm1/0aZKr9Mw+4mWPBefQ==

Here is an example showing how to set this in prj.conf:

CONFIG_CHIP_DEVICE_DISCRIMINATOR=0x231
CONFIG_CHIP_DEVICE_SPAKE2_PASSCODE=20372039
CONFIG_CHIP_FACTORY_DATA_GENERATE_SPAKE2_VERIFIER=n
CONFIG_CHIP_DEVICE_SPAKE2_TEST_VERIFIER="kLXow6J5EYWRa3aO71DkTG5qMtkn5PfwwXhOixGa2zEEDEDGlKfe7mEBAg6b3CTx++XPKapVRxnuWs6r6O90+7aDXjlDytFVwlS+PVpSY3dQTmm1/0aZKr9Mw+4mWPBefQ=="

Please note that these Kconfigs should only be used for testing purposes.

Best regards,
Marte