proposal: crypto/tls, crypto/x509: EdDSA certificates support

[FiloSottile]

Ed25519 and Ed448 certificates are finally coming.

https://tools.ietf.org/html/draft-ietf-curdle-pkix-07 is the draft for X.509, and Ed25519/Ed448 are supported directly by TLS 1.3.

The implementation is not hard and I have a branch of it already: master...FiloSottile:filippo/ed25519

The problem is that we'll have to vendor golang.org/x/crypto/ed25519 for the primitive functionality (like we did with golang.org/x/crypto/curve25519), but that will mismatch the PublicKey and PrivateKey types, which are exposed to the user in tls.Certificate.PrivateKey and x509.Certificate.PublicKey. A user-supplied ed25519.PrivateKey would not type-assert to the vendored ed25519.PrivateKey, and a parsed ed25519.PublicKey would not type-assert to the application side one.

I can think of three decent solutions off the top of my head:

1. define Ed25519PublicKey and Ed25519PrivateKey types in crypto/x509, which are easy to cast to/from, as they're nothing but []byte; if/when we promote ed25519 to the stdlib, alias and deprecate them

2. use []byte for both types, document it

3. simply promote ed25519 to the stdlib

We also need to decide if we want to bring Ed448 on board at the same time. We don't have a Ed448 implementation yet.

See also: https://groups.google.com/forum/#!topic/golang-dev/FNfJzm-BDno

[arunjohn99]

Thanks, @FiloSottile . I really like option 3, clean and consistent with existing approach. Followed your footsteps and ported the changes for ed25519 under crypto package to support option 3

[mattghali]

hi there, i am trying to get Wireguard key generation going inside terraform, using terraform-provider-tls, and ed25519 support in the x509 module would make it really easy.

[arunjohn99]

@FiloSottile Given that we are probably 2-3 weeks away from 1.12 release, can you confirm whether this would make it to 1.12

[FiloSottile]

Definitely not, the proposal is not decided yet, and 1.12 has been in feature freeze for months.

[arunjohn99]

Bummer! Any thoughts on when this would be supported?

[FiloSottile]

The more detailed reports of how this would be used we have, the more likely it is that it will be soon. It's a matter of prioritization, and of making sure we are not adding to the stdlib something we don't really need.