[Questions]DAC private key confusing

[susepc]

Dear all:

        AFAIK, DAC contains the device's identity information and the manufacturer's signature.

        On the other hand, The private key is used to generate the manufacturer's signature.

        Is it possible not to store the DAC private key due to signature has been existed in DAC?

dac_cert	(DAC) Device Attestation Certificate	<1, 602> B	byte string	mandatory	The Device Attestation Certificate (DAC) and the corresponding private key are unique to each Matter device. The DAC is used for the Device Attestation process and to perform commissioning into a fabric. The DAC is a DER-encoded X.509v3-compliant certificate, as defined in RFC 5280.
dac_key	DAC private key	68 B	byte string	mandatory	The private key associated with the Device Attestation Certificate (DAC). This key should be encrypted and maximum security should be guaranteed while generating and providing it to factory data.

BR

Chuan

[Marte Myrvold]

Hi Chuan,

The Matter specification states that all commissionable Matter nodes shall include a DAC and the corresponding private key, so the DAC private key is mandatory. You can also see this in the Factory data component table where the DAC private key is listed as mandatory.

Best regards,
Marte

[susepc]

 Marte Myrvold 

        Thanks for your reply!

        Although DAC private key is mandatory in matter specification, but I still want to know the reason, may I ask if you can let me know?

BR

Chuan

[Marte Myrvold]

Hi Chuan,

I recommend asking the CSA, who is responsible for the specification, about this, as I do not have information regarding the reasons for decisions made in the specification.

Best regards,
Marte