"We found that when using features such as Airdop and Nearby, devices emit messages from which email addresses and phone numbers can be extracted. Continuity services allow to seamlessly share resources with nearby devices: Airdrop to share files, Nearby to share Wi-Fi network credential. Prior exchange of information, the devices establish their identity by exchange identifiers over BLE: email addresses and/or phone numbers. Those identifiers are not sent in clear but are rather hashed using a cryptographic hash-function. This obfuscation can be bypassed in most cases and the identifiers recovered."