Kupyna: implemented hashing function

[AnarchistHoneybun]

function spec

Scrapped previous PR since it ran into a lot of problems. I'm aware that #601 exists, creating this one to check against the repo's test suite as I iterate on my implementation, and potentially make it the main pr for kupyna if the other one becomes inactive.

Currently the implementation does everything the paper describes (testing leaves a bit to be desired) so step one is to clean up any linter complaints, and then proceed to making it no-std compatible.

[AnarchistHoneybun]

@newpavlov could you give me some idea on why the tests are failing right now? I don't think I've touched the Cargo.toml let alone the version of digest; checked and it's the same version as that present in some other toml's. Any idea why this could be happening?

[AnarchistHoneybun]

Might be a bit unrelated but when I try cargo run on my local it gives me this error:

error: failed to select a version for `digest`.
    ... required by package `kupyna v0.1.0 (/home/vrin/kupyna_hashes_contrib/kupyna)`
versions that meet the requirements `=0.11.0-pre.9` are: 0.11.0-pre.9

all possible versions conflict with previously selected packages.

  previously selected package `digest v0.11.0-pre.8`
    ... which satisfies dependency `digest = "=0.11.0-pre.8"` of package `ascon-hash v0.3.0-pre (/home/vrin/kupyna_hashes_contrib/ascon-hash)`

failed to select a version for `digest` which could resolve this conflict

now this worked fine before updating the toml. Post toml update the CI is fine, but the main function is failing. Is this expected behaviour?

[newpavlov]

Try to rebase your branch to master.

[AnarchistHoneybun]

I don't have a lot (read any) experience with rebasing, sadly. Could you explain a bit more?

[newpavlov]

You should be able to rebase to this repos master using something like this (it accounts for the fact that you've forked from a fork):

git remote add upstream [email protected]:RustCrypto/hashes.git
git pull upstream
git checkout main_repo_contrib
git rebase upstream/master
git push --force

Note that I do not guarantee correctness of these commands since I wrote them from memory.

[AnarchistHoneybun]

rebased and made the hex formatting changes. I was wondering if I should also format the mds and s-box matrices the same way, but i think it'd make me put hex-literal as a proper dependency instead of a dev dependency.
Any particular way you want me to approach this?