go_chacha20poly1305_openssh/README.md

# cc20p1305ssh

A Golang library variant of ChaCha20-Poly1305 that OpenSSH uses ("chacha20-poly1305@openssh.com").

Note that this module *only* supports the OpenSSH variant.

## Why is this necessary?

Because Golang.org/x/crypto [removes functionality](https://github.com/golang/go/issues/36646) (even for [very common tech](https://github.com/golang/go/issues/44226)) and thinks OpenSSH is a "weird" use case.

They have no decent support for OpenSSH keys or lower-level operations. And guess what -- sometimes you need lower-level functionality. Who knew?

So now because I'm just a single individual, bug fixes will probably lag behind upstream. All because Golang.org/x/crypto decided the OpenSSH variant was "too weird".

But, of course, not "weird" enough to [not support the *wire* protocol](https://go.googlesource.com/crypto/+/master/ssh/cipher.go#647) for SSH. Just the key encryption. Because of course. And not publicly exposed either. Because of course.

## Why is the name so ugly?

I couldn't think of a better one and I wanted something notably distinct from stdlib-x.

## Why don't you expose the rest of ChaCha20/Poly1305/ChaCha20-Poly1305?

* To keep code light (and thus easier to debug, audit, etc.)
* Because otherwise the module name is inaccurate
* Because OpenSSH has their own specific variant
  * Which means we can handle SSH-specific functionality if needed
* Because Golang/x/crypto has made it painfully clear that if you want something that deviates from what they think is "best practice", you need to do it yourself


Based on [golang.org/x/crypto/chacha20poly1305](https://pkg.go.dev/golang.org/x/crypto/chacha20poly1305) (source specifically forked from [chacha20poly1305](https://cs.opensource.google/go/x/crypto/chacha20poly1305), [chacha20](https://cs.opensource.google/go/x/crypto/chacha20), and [poly1305](https://cs.opensource.google/go/x/crypto/internal/poly1305])), sliced, diced, and ripped to pieces. Based from commit 793ad666bf5ec61392092b27061be9618e4e219b via repo https://github.com/golang/crypto.git (mirror of git://cs.opensource.google/go/x/crypto), fetched on Jun 5, 2022 at 0656EST5EDT.

Because the code is minimally modified, the majority of the code's original license can be found via LICENSE.forked (of which the source can be found above).

Namely, some of these specific modifications are:

* "Exporting" certain previously private methods
* "Exporting" certain previously private struct fields
* Changing certain constants and logic conditions