openhaystack VS TTGO-T-Display

> For Find My, since they can even locate switched off phones

They can't. Find My is actually truly end-to-end encrypted, at least the version used for when a device is off (I'm not 100% sure how encrypted the self-reported version is for powered on iPhones with data).

Copy-pasting my summary about how Find My works from another comment in this post:

> The master private key used by the system is generated locally and never leaves your Apple devices in a state that anyone except your devices can read it.

> The master key is used to derive an AirTag specific private key which is provisioned to the AirTag and is in turn combined with an increasing counter which generates a third private key that's never stored anywhere. The ID broadcast is the public key of this third key. It changes every 30 minutes or 1 hour, I forget which.

> Other devices see this key, use it to encrypt their own location, and upload that encrypted blob along with the public key to Find My, and in order for Apple to even know which account the encrypted blob they can't decrypt belongs to I have to actually request the location of my AirTag by locally deriving the keypair it used for a certain point in time.

This has all been proven through [1] where they read the whitepaper (which I can't for the life of me find now but know exist because I've read it, or at least parts) and implemented OpenHaystack which proves Apple aren't lying about anything because if they did then OpenHaystack wouldn't work.

1: https://github.com/seemoo-lab/openhaystack

find my network

Much more nuance than that. You can't just tap into the networks. More information here https://github.com/seemoo-lab/openhaystack

You can actually create your own, using Apple's "find my" network. See OpenHaystack

Technically you could just put a USB battery bank inline with your power source, and it would work as a backup in case the main USB power source was disrupted somehow. The only real downside to this is there wouldn't be any easy way to monitor the status of the battery (ie, power remaining), nor whether you were running off battery or not. Another alternative is any of the ESP32's that have battery support built in - LILYGO/TTGO are my goto boards generally, and I use this one whenever I need one with a display: https://www.amazon.com/LILYGO-T-Display-Arduino-Development-CH9102F/dp/B099MPFJ9M?crid=28TOIB8GQ81GQ&keywords=ttgo+battery&qid=1678137098&sprefix=ttgo+batter%2Caps%2C634&sr=8-9&linkCode=ll1&tag=ana024-20&linkId=e20b8c0eb33ea824d3d16401bcc67f34&language=en_US&ref_=as_li_ss_tl and their github repo: https://github.com/Xinyuan-LilyGO/TTGO-T-Display Pin 14/34 let you tell more about the battery state - there's some good discussion about it here: https://github.com/Xinyuan-LilyGO/TTGO-T-Display/issues/35

Here's a light sleep example that I pilfered from Lilygo demo code:

The demo that should be loaded by default is at https://github.com/Xinyuan-LilyGO/TTGO-T-Display

Picture

On the TTGO T-Display, the display backlight is connected to GPIO 4. You can turn it off with digitalWrite(4, LOW) like the factory test firmware does before entering deep sleep.