Fscrypt's Adiantum Sent In For Linux 4.21 For Speedy Disk Encryption On Low-End Hardware

Waiting until the last day of the Linux 4.21 kernel merge window, Ted Ts'o sent in the fscrypt changes today adding Adiantum crypto support to this file-system encryption framework currently used by F2FS and EXT4.

Adiantum was added to the crypto code earlier in the Linux 4.21 merge window as Google's replacement for Speck. Their Adiantum (and formerly Speck) motivation was for being able to offer data encryption on low-end "Android Go" devices where the SoCs lack hardware extensions for accelerated encryption. Adiantum can perform well on low-emd ARM Cortex processors, thereby opening up EXT4/F2FS encryption for these budget smartphones.

Besides Adiantum not carrying the baggage of being developed by the US National Security Agency (NSA) that led to the public outcry around Speck, Adiantum is faster than Speck so it's a win-win for developers and users.

With this PR adding Adiantum to the fscrypt code, it can now be used by EXT4 and F2FS as the current fscrypt users within the mainline kernel.

I'll be working on some Adiantum fscrypt encrypted storage benchmarks soon.