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I want to send encrypted data from ble (as central) to another device (as peripheral). Now when app is open everything is all good, but what to do if app is in background? Do I have to buy smaller version of advertising id from BLE SIG? OR Is there any way I can send data in background? Or Is there any unique characteristics or services other than BLE ADDRESS that iPhone always advertises when iOS Bluetooth is turned on, so that I can check on that condition and allow entry to user (as application is for smart door lock.)