CoreBluetooth iOS api changes: BLE 4.0 vs BLE 4.2

Question

I am trying to get under the hood of BLE 4.2 and how this affects the product design as well as iPhone development.

• A: What are the CoreBluetooth API changes to support BLE 4.2?

  • Has there been any?

• B: How is device pairing implemented in 4.0 and how is it implemented in 4.2?

I understand that one of the main security improvements in BLE 4.2 is that it does not use the pairing key to generate a set of public/private encryption keys. However I haven't seen an example yet of this and would like to understand it a bit better.

• C: Is there a security/pairing CoreBluetooth API in iOS?
  • Does this differ for 4.0 to 4.2 devices?