feat: add subject URIs to index for x509 certificates

[asraa]

Signed-off-by: Asra Ali asraa@google.com

Summary

Adds URIs to x509 certificate "email addresses". This picks up on job workflow ref for Fulcio issued certificates.

Ideally I'd like to deprecate EmailAddresses() in favor of Subjects() -- should I add Subjects() and mark EmailAddresses() as deprecated? I'm not sure there's much external usage.

Ticket Link

Fixes

Release Note

* pki: Deprecates `pki.PublicKey.EmailAddresses()`. Use `pki.PublicKey.Subjects()` instead to include subject URIs from public keys like x509 certificates.

[bobcallaway]

nit:

Suggested change

	errs := validate.Var(name.String(), "required,uri")
	if errs == nil {
	names = append(names, strings.ToLower(name.String()))
	}
	}
	if errs := validate.Var(name.String(), "required,uri"); errs == nil {
	names = append(names, strings.ToLower(name.String()))
	}
	}

[imjasonh]

Are these validation errors surfaced anywhere before/after this? It seems a waste to drop perfectly good validation errors from end users (...says the end user most likely to send invalid values 🙃 )

[asraa]

This ones a little tougher to surface -- I expect that this one is relatively difficult to hit, because Fulcio is the one populating certificates and it's not user-controlled.

On that note maybe it's worth filing an issue that we surface what keys WERE successfully indexed when you upload something?

[haydentherapper]

FWIW, it's also worth noting that it might not be Fulcio's certs uploaded to the log, as users can upload certs from their own PKI.

[bobcallaway]

Ideally I'd like to deprecate EmailAddresses() in favor of Subjects() -- should I add Subjects() and mark EmailAddresses() as deprecated? I'm not sure there's much external usage.

I'm fine with that.

[imjasonh]

Ideally I'd like to deprecate EmailAddresses() in favor of Subjects() -- should I add Subjects() and mark EmailAddresses() as deprecated? I'm not sure there's much external usage.

I looked, and sget uses EmailAddresses(), but I don't mind having to switch when I bump the dep.

[asraa]

Added Subjects() and a deprecation notice on EmailAddresses()