Is Android officially supporting CTKD? From the BlueZ documentation:
Another improvement that LE SC brings is what’s called cross-transport key derivation. What this means is that when two dual-mode (supporting LE + BR/EDR) devices pair with each other, they only need to pair over either LE or BR/EDR to get the encryption keys for both transports in one go.
I haven't found any information in the official Android docs.
There is no documentation about it, but it is supported, take a look to:
I was able to trigger CTKD (BLE -> BR/EDR) connecting to GATT (BluetoothDevice::connectGatt) and when the connection state becomes STATE_CONNECTED then trigger the pairing request (BluetoothDevice::createBond). Then I got paired to BLE and CTKD generates the BR/EDR link key.