Adiantum: encryption for the low end

> Two rounds of XChaCha12 are followed by an AES-256 encryption, but of just 16 bytes

I am not a cryptographer so I am a bit clueless on topics like this but I am wondering, why are they doing this? Does this provide any significant benefit to just chacha12 or chacha12 + poly1305?

I was curious too, found answer in comments of original publication:

> Normally there is just one XChaCha12 invocation per encryption or decryption. There's another to derive subkeys, but that's only needed when setting a new key.

I don't understand why they use AES though.

I'd be really interested to try out a Go port of this. Given that Adiantum is a construction built from existing primitives, should I expect that it won't be difficult to port?

What was wrong with chacha?

Never mind, I didn't finish reading.