CODEWITHSUNDEEP
bluetooth-lowenergy
mint branch conditioner
mint branch conditioner

Reputation: 193

BLE is the intention of the "Access Address" to be rolled randomly?

Follow up of What is the purpose of "Access Address" in BLE

Is the peripheral's access address randomly generated? Rolled per connection? I am aware the "r" MACs are rolled to prevent tracking so I would also assume the AA is?

Why didn't the BT SIG just make the AA and the MAC to be the same thing? Is there a good reason or functional difference the MAC wasn't bumped from 48 to 64 bits and replaced the Access Address? Holdover from BT Classic?

I haven't seen a good reason that access and mac would co-exist.

Upvotes: 0

Views: 694

Answers (1)

Emil
Emil

Reputation: 18497

The access address is different for every connection and identifies the connection. Every new connection uses a newly randomized address.

If you use the Bluetooth Device addresses, should you use the central's address or the peripheral's, or a concatenation? Note that these are longer than 32 bits. Note that two BD adresses might differ by only one bit if they are produced in sequence. If only for example the central's BD address was used as "access address", then it can't have multiple connections in a reliable way.

The access address also has a lot of rules of forbidden bit patterns. This is to avoid mistaking noise or silence as a new packet, and to "lock" the radio synchronization.

So, there are a lot of good things with the access address.

Upvotes: 1

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