Establish a secure channel using libOSDP

[mbratch]

I am using the libOSDP in an ESP32 for a PD.

In reading the OSDP specification, the process of establishing a secure channel is fairly elaborate. My question is: what does libOSDP handle itself versus what does it expect my application to do to facilitate? I think, after reading through the libOSDP source, all I need to do is respond to the KEYSET command and copy the requested data into the scbk for my PD?

Thank you for any assistance. This is a very helpful library. :)

[sidcha]

Hi @mbratch, yes, LibOSDP handles all secure channel initialization and and session management as described in the specification.

During PD setup, you are supposed to pass a SCBK. This key will be used to setup a secure channel with a CP that also knows this SCBK. But for the very fist time the PD needs to be placed in a special mode called INSTALL_MODE (a provisioning time mode which should not allowed in production for security reasons). During this mode, the PD will use the SCBK-D (a default key) to setup a temporary secure channel as one-time activity. Once this temporary session is created, the CP will set a new SCBK using they KEYSET command. The PD app will receive a command callback from LibOSDP with the new SCBK which it must store to a non-volatile storage and in subsequent PD setup calls, pass this key.

Also, please read about the ENFORCE_SECURE flag and why its needed.

[IDmachines]

It is also critical that setting the default key be done in a secure location, effectively air gapped from the system. There has been unwarranted criticism that this process is a vulnerability when in fact it is something that requires best practice. It is also critical that a unique key pair is assigned for each controller (CP or ACU) to reader (PD) pairing. This is also true if a secure channel reset needs to take place.

[mbratch]

Thank you very muich @IDmachines @sidcha that helps a lot.