Secure wireless link between two devices using probes

A method for establishing a wireless communication link between an accessory and a controller, the method comprising:

• receiving, by the accessory, a first probe from a controller, the first probe indicating that the controller is searching for an accessory with which to pair;
• sending, by the accessory, a second probe to the controller in response to the first probe;
• establishing, by the accessory, a shared secret with the controller, wherein establishing the shared secret includes exchanging public keys with the controller using a plurality of additional probes including at least a third probe sent by the accessory and a fourth probe received by the accessory;
• validating, by the accessory, that the shared secret is shared by the controller;
• generating, by the accessory, a further cryptographic key using the shared secret;
• receiving, by the accessory, a fifth probe from the controller, the fifth probe containing an encrypted message;
• and
• decrypting the encrypted message using the further cryptographic key.