# Ledger Nano X implants were using nRF91 LTE-M/NB-IoT radios

Source: https://x.com/kevospore/status/2108832720256197113

## Summary

Ledger Nano X implants that use nRF91 LTE-M/NB-IoT radios are described as well suited to covertly sending out seed phrases. The reasoning is that a 24-word seed is about 250 bytes, which is a sweet spot for these radios rather than a constraint. NB-IoT and LTE-M were built for tiny, infrequent messages with low power that blend into normal IoT traffic, and the modem type has gone largely unremarked.

## Article

Just realized why the Ledger Nano X implants using nRF91 (LTE-M / NB-IoT) are quietly brilliant:

A 24-word seed is around 250 bytes. That’s not a data constraint for these radios instead it’s their sweet spot.

NB-IoT/LTE-M were built for tiny, infrequent messages. One short transmission, low power, blends into normal IoT traffic. No high-bandwidth connection needed. The same limitation that makes them useless for bulk data makes them perfect for quietly walking off with a seed.

The interesting part isn’t that someone added cellular. It’s that they picked a radio whose design goals align almost perfectly with the attack and nobody is speaking about the type of the modem.