proposal: crypto/x509: writing certificates in PKCS12 format

[boumenot]

The code contributed to the go-pkcs12 repo for reading PKCS12 format had a pull request for writing PKCS12 format too, but it was decided to hold off on write support until after read support was merged. I propose that this change now be included.

@AGWA is the original author, but I am happy to bring his changes over too.

[AGWA]

An updated version of my PKCS#12 writing code can be found here: https://github.com/AGWA-forks/golang-crypto

I believe it's in good shape, but I haven't had chance to deal with the CLA yet.

[gopherbot]

CL https://golang.org/cl/20075 mentions this issue.

[adg]

Given @agl's objections on the CL, I am declining and closing this proposal. Thanks.

[nathany]

Also, while parsing PKCS#12 files is a plausible use since they do exist, they should be strongly discouraged. Supporting their serialisation seems counter to this.

There are plenty of other cryptography packages in Go who's use is discouraged. #14395

It's a bit unfortunate that after Microsoft made an effort to add pkcs12 to x/crypto, they are left forking it to support writing, which will likely leave x/crypto outdated compared to a more complete implementation elsewhere.

In my particular case, Apple appears to be moving away from pkcs12 certificates, at least in the case of push notifications, so I don't have a strong argument to support them.