Through Android Go, Google seeks to extend the encryption of storage on smartphones up to entry level.

What is the common point between the Archos Access 57, the Nokia 1 Plus and the Xiaomi Redmi Go?

The three smartphones ship Android Go .

This lightweight version of the operating system is intended for, according to Google, devices with 1.5 GB of RAM or less.

Launched in 2018, it will be the subject of its first major update this Fall in the wake of the Android platform .

Google just communicated that this update will be focusing on improving performance: the system will switch faster between applications and their launch will be “10% faster” than with the current version.

Among them, Google Go will read aloud and will benefit from the integration of the Lens tool for image recognition.

Adiantum: encryption for everyone?

On the security side, the main novelty is the implementation of Adiantum .

Since Android 6.0, Google generally requires storage encryption on devices with its OS.

It uses the algorithm AES (Advanced Encryption Standard).

The ARMv8 instruction set provides AES support at the hardware level.

On devices with older processors, software support is required and performance drops accordingly.

In this context, Google made an exception for devices where AES data rates do not exceed 50 MiB/s and went in search of alternative solutions.

To encrypt HTTP traffic, the American group has chosen the ChaCha algorithm, which exploits operations that all CPUs natively support (addition, rotation, exclusive OR).

It has been associated with Poly1305, all of which is defined in RFC 8439 (RFC 7539 until May 2018).

Adantium uses the RFC 7539 specification, but is suitable for disk encryption.

The challenge: to ensure that requests to the file system, despite the inclusion of a nonce and an authentication code, have the same size as the addressed physical sectors.

Otherwise, a read or write operation would affect two sectors, doubling the time needed and theoretically decreasing the storage media lifetime by half.

At ChaCha20, which performs 20 steps of mixing its input data, the ChaCha12 reduced version was preferred.

Google is reassuring consumer by reminding them that ChaCha8 has not been broken yet.