cipher v0.3.0 release

[tarcieri]

This is a tracking issue for a final v0.3.0 release of the cipher crate, containing such changes as refactored block cipher traits (#352), unified error types (#373), and lots of cleanups of things that were missed with the "initial" release of the cipher crate (v0.2, bumped from the v0.1 releases before we owned it).

From my perspective it's ready to release, however there are at least a few things it might be worth considering getting in there before we do:

• cipher: remove generic_array re-exports from block and stream modules #344: make dev modules private, re-export blobby from toplevel
• cipher: merge block-modes crate #272: merge block-modes crate into cipher

@newpavlov any others?

[newpavlov]

I have a draft with changes, which I would like to add to the v0.3 release. They include some renamings (e.g. SyncStreamCipher -> StreamCipher, StreamCipher -> AsyncStreamCipher), code reorganization, addition of a modified block mode trait. I got stuck on designing a trait for exposing block nature of stream ciphers (the block-buffer PR is part of this work), but I probably will postpone it for a later patch release. I also consider adding a trait for AE, but I haven't found a good API for it yet which would fit nicely with the block mode API.

[tarcieri]

The renamed traits sound great!

[tarcieri]

@newpavlov I'm happy to punt on #444 until after cipher v0.3.0

How do you feel about #510? What else is remaining? A block-modes integration?

[tarcieri]

How about an end-of-February (i.e. ~March 1st) deadline for a v0.3.0 release?

[newpavlov]

Yes, sounds good! I plan to return to cipher after finishing with RustCrypto/hashes#217.

[tarcieri]

Checking in on this: how are we doing?

@newpavlov looks like you've merged quite a bit lately. I'm not sure what's remaining for a release. Is there anything I can help with?

[tarcieri]

@newpavlov what specifically remains to be done here?

[tarcieri]

I'm thinking if we can't get another cipher release out e.g. this week that it might make sense to cut another cipher prerelease along with prereleases of the most used AEAD crates to unblock people who are stuck on the rand_core upgrade.

[newpavlov]

Sorry for the delay! I plan to update the cipher PR today with some significant changes.

[tarcieri]

@newpavlov was #567 the PR you're talking about above, or per the notes in that PR are you planning a follow-up?

[newpavlov]

@tarcieri
Yes, I am currently working on it. Unfortunately the previous direction was quite an over-engineering after I've looked on it with fresh eyes, so I try to simplify it now. The main idea is to inverse control, instead of looping in higher-level code I plan to transfer control over it to block ciphers implementations. Since it's be done via callbacks (one for filling slice of blocks and second for processing encrypted/decrypted results) and since they are effectively inlined, my hope is that it will result in near optimal performance. But there are some complications, e.g. some block modes require pre-encrypted blocks, another one is that it's unclear how to properly combine encryptor/decryptors with MACs. They may have different parallel block sizes, so in theory we should find least common multiple, but we can not do it with the callback approach.

[tarcieri]

Checking in once again on how we're doing here.

At this point things are really starting to get problematic for me as this is holding up the upgrade to rand v0.8 / rand_core v0.6. Pretty much the rest of the ecosystem has updated, including most recently the rsa crate. I'm getting pretty frequent questions from people who are confused why there are type system errors trying to use newer versions of rand with the current crates.

I can get immediately unblocked on things by cutting releases of the ecdsa crate using the current release of hmac along with releases of the https://github.com/rustcrypto/elliptic-curves crates, which would unblock me immediately on the rand updates. I was holding out hoping we could do a synchronized update there, but if it's going to take awhile longer I'd really not continue to delay.

In hindsight I kind of wish we just released cipher v0.3 unchanged from the v0.3.0-pre.4 release I cut December 2020. It's also holding up things like releasing the first versions of crates with runtime autodetection of SIMD features, along with the new stream module in the aead crate.

[tarcieri]

I have a potential proposal to unblock all of the above which I think would be relatively simple to execute given the current state of the repos. First, the crates in https://github.com/RustCrypto/universal-hashes/ are ready to release, so everything else aside I can go ahead and cut new releases of those.

Beyond that:

The block-ciphers repo is currently using the 0.3.0-pre.4 release of cipher as published to https://crates.io

I propose making a final v0.3.0 release of cipher which is otherwise identical to 0.3.0-pre.4, followed by a v0.11.0 release of crypto-mac which includes the cipher updates.

Aside from bumping crypto-mac, everything else is ready for another release all the way up through aead, which is updated to aead v0.4 and is only (aside from universal hashes) blocked on bumping block ciphers/stream ciphers.

@newpavlov WDYT about that? I think it would give you more time to work on additional changes to cipher. If you think you'll be done with what you're working on soon, great, but otherwise in the past few weeks the v0.3.0 cipher release has become the one thing blocking everything I outlined in my previous comment.

[newpavlov]

@tarcieri
Sorry again! I got distracted by other stuff and was not able to work much on it lately. Give me several days and I will publish relevant PRs, after that, depending on your opinion of the proposed changes, we can either finalize them or publish the current state of repos as v0.3 and publish the changes as v0.4.