Open Source Summit Europe 2025

In the last year Zephyr’s cryptographic support saw a lot of changes, the main ones being the deprecation of TinyCrypt and an increased usage of PSA Crypto API following the long standing goal to move toward a common interface for crypto operations.

The main reason for TinyCrypt deprecation is basically that it’s no longer maintained so it cannot get any security fix/improvement nor be adapted to the upcoming PSA interface. This basically leaves Mbed TLS as the only crypto provider in Zephyr, which can either used directly (i.e. building Mbed TLS as library to be linked against other Zephyr’s ones) or being integrated in TF-M image.

This talk will start from an overview of the recent history of Zephyr’s crypto support, presenting reasons for TinyCrypt deprecation and the adoption of PSA Crypto API. The focus will then shift toward Mbed TLS as the only crypto library available today in Zephyr, its layers (TLS and crypto), how it relates to TF-M and the recent improvements added to reduce footprint problems. In the last part of the talk we’ll focus on the future plans for Mbed TLS: what to expect from the next release which is expected in September 2025 and vendor driver support.