Add SHA3?

[mperham]

Would you be ok with a PR adding SHA3? I'd integrate the code here:

https://github.com/mjosaarinen/tiny_sha3

which is MIT-licensed. The C code is a single, short file and has the init/update/finalize API that all Digests seem to use.

There are two existing rubygems which provide SHA3 but the C code is more complex.

https://github.com/phusion/digest-sha3-ruby
https://github.com/johanns/sha3

See also #10

[nobu]

tiny_sha3 seems not portable.

This looks assuming gcc only.

#if __BYTE_ORDER__ != __ORDER_LITTLE_ENDIAN__

[kotovalexarian]

Be careful with naming. What some people call SHA3 is actually a draft version of it, now known as Keccak. It's what Ethereum uses AFAIR. Final SHA3 is different. Maybe they both may be implemented under their proper names.

[kotovalexarian]

There is my fork of SHA3 by Phusion, properly renamed to Keccak and fixed for Ruby 3.4:
https://github.com/kotovalexarian/digest-keccak