Change Characteristics' Read/Write Permissions While Connected

RE: Change Characteristics' Read/Write Permissions While Connected

jfDEVmoto — Wed, 02 Nov 2016 22:45:15 GMT

Hello. Is this still true with SD130 and SDK 11 ? Can I connect and do pairing and bonding and then perform an app level authentication and then add a service or chars ?. My experience is that when I add chars to my app, i have to reset bonding and pairing on both sides to be able to bond again and discover the new services. I am using the device manager, not peer manager.

RE: Change Characteristics' Read/Write Permissions While Connected

pltv — Mon, 19 Oct 2015 20:13:25 GMT

Hello. I would like to adopt approach 1 suggested above in a similar case. Could you point out how to handle GATT table updates. Currently any value written automatically updates the value in the characteristic in the peripheral. I would like to not do that unless the central has been validated

RE: Change Characteristics' Read/Write Permissions While Connected

Ole Morten — Mon, 28 Apr 2014 11:46:01 GMT

The only way to clear the GATT Table is to disable and re-enable the softdevice, and then not add it back in. There are no API function to remove a service. I would however rather recommend going with the first approach, simply to avoid this hassle.

RE: Change Characteristics' Read/Write Permissions While Connected

Samuele Forconi — Wed, 23 Apr 2014 10:35:56 GMT

Hi, using the solution 2, how can I remove the "protected" service from the GATT Table when the Central device disconnects from the Peripheral? I think that if I don't remove the "protected" service when the Central disconnects, then at the next connection the Central is able to discover the "protected" service, is that right?

RE: Change Characteristics' Read/Write Permissions While Connected

Ole Morten — Tue, 04 Mar 2014 11:43:20 GMT

What you want is in itself not currently possible, since you can't change already added services or attributes. However, I think there are at least two possible ways to work around this:

Don't use the data you receive in the events, or populate the GATT Table with valid data before the peer device has been authenticated. Since all the activities done from the Peripheral side is controlled from the app, the only result of this should be that an attacker would be able to read 0s or write random data, but which will have no effect.
Don't add the protected services before the peer device have been authenticated. Although you can't change already added services, you can add new services, so if you start off with just the authentication service, you could add the other services only after authentication have passed. Beware that you'll most likely have to send a Service Changed indication to the peer device for this to work properly, to let the Central know that new the GATT Table have changed.