Add blake3

[lukechampine]

Adds functions corresponding to the exported blake3 arms in urbit/urbit#6802

I'm out of my depth when it comes to C build systems, so I will need help getting this to build... 😅

[matthew-levan]

Nice, this should be done soon. I just pushed a commit that hopefully gets you a little further along the build process. Still hitting 13 errors (mostly related to undefined symbols) during make, but do check out how I updated configure.ac and Makefile.am to continue this work.

[matthew-levan]

@lukechampine Should work now.

[lukechampine]

Thanks! Some thoughts (mostly reminders for myself):

• output_t is kinda big; we should either ensure that calls to urcrypt_blake3_chunk_output and urcrypt_blake3_parent_output are inlined, or pass an outparam instead
• urcrypt__reverse isn't called on anything within output_t; this is probably fine since callers should be treating output_t as opaque anyway, but something to be aware of
• For maximum performance, we will want to call blake3_hash_many, which hashes up to 8 chunks in parallel using SIMD. Perhaps we should expose that instead of urcrypt_blake3_chunk_output, which only hashes 1 chunk (and requires us to export some blake3 guts that weren't meant to be exported)

I'll try to get some jets working using your msl/fetch-urcrypt branch soon :^)

[lukechampine]

Planning to revisit this soon in light of the verified streaming work that I recently finished.

I think we really only need three jets:

• +hash:blake3, for general purpose usage (and maximum throughput for large messages)
• +chunk-output:blake3, for turning a chunk into an output
• +compress:blake3, for turning an output into bytes

Importantly, the +chunk-output jet should not return an output_t -- that ends up being more trouble than it's worth. Instead it can return just the cv; the client can figure out the rest of the fields itself.

[lukechampine]

@matthew-levan this should be good to merge!

[joemfb]

this will do

[joemfb]

this will do