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I have read reports that expected throughput on iOS devices is up to 3 kilobytes per second (for example, the article here), but these reports seem to measure the throughput only for unpaired devices, which means no encryption.

My peripheral is sending sensitive data and I want to encrypt it. Let's assume, that the peripheral itself is much faster, e.g. an Android device with 7.5ms connection interval, 6 packets per connection event and ATT MTU negotiation support (but no LE 4.2 Data Packet Length Extension), thus the throughput depends entirely on the slow iDevice (usually 30ms connection interval, 4 packets per connection event).

What is expected reduction of throughput if I enable encryption on a GATT characteristic?

Preferably, I'd like to see real life measurements on iOS devices instead of theoretical calculations.

JustAMartin
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Since the auth tag is 32 bits long when using encryption, the transfer will take 32 microseconds longer per non-zero length packet. It depends entirely on the Bluetooth chip in the particular iDevice if it will schedule less packets per connection event or not. Since they don't document the behaviour I think the only way to find out is to test with various phone models and see what happens.

Emil
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