[$] Adiantum: encryption for the low end

Low-end devices bound for developing countries, such as those running the Android Go edition, lack encryption support because the hardware doesn't provide anycryptographic acceleration. That means users in developing countries haveno protection for the data on their phones. Google would like to changethat situation. The company worked on adding the Speck cipher to thekernel, but decided against using itbecause of opposition due to Speck's origins at the US NationalSecurity Agency (NSA). As a replacement, the Adiantum encryption mode wasdeveloped; it has been merged for Linux 5.0.