Adiantum Queued Ahead Of Linux 4.21 As Google's Speck Replacement

Adiantum is the new crypto algorithm Google is backing for disk encryption on low-end (Android) devices following their change of course regarding the controversial NSA-developed Speck algorithm earlier this year.

Initially after Google abandoned their Speck plans following public outcry, they were developing HPolyC for encryption on low-end hardware. Adiantum took things a step further as being based upon an improved version of HPolyC. Early tests of Adiantum show it being about four times the speed of AES-256-XTS for encryption and around 5x for decryption. This is also about 30% faster than Speck128/256-XTS and 20% faster than the original HPolyC without compromising any security. This is great news for low-end CPUs/SoCs that generally lack native crypto extensions in the hardware.

The initial Adiantum crypto code is now queued into the crypto-next tree where it is staged until the Linux 4.21 kernel merge window opens in about one months time. We haven't yet seen the Adiantum code staged for adding that support to fscrypt to then offer Adiantum-based native file-system encryption for EXT4/F2FS, but that will still likely come via its respective trees unless it ends up getting pushed back to Linux 4.22.

Also queued are AVX2 and AVX-512 optimized versions of ChaCha20, which can bring ~20% speedups, ARM NEON optimizations, and other tuning related to the Adiantum landing.