*ring* interoperability issues with RSA

[djc]

Problem:

In hickory-dns/hickory-dns#2778 I am preparing to add an aws-lc-rs backend to a pre-existing ring crypto backend for Hickory's DNSSEC implementation. In porting the code, I found one issue where the aws-lc-rs API currently does not seem to offer a capability that ring offers, and there's one piece of API that ring deprecated for which aws-lc-rs does not have the replacement. In order to make this a smooth transition, it would be great if these could be addressed, though I'm also happy to take on some wrapper code to make things fit.

Main issue:

djc-2021 actuallly-aws-lc proto $ cargo c --features dnssec-aws-lc-rs --all-targets
    Checking hickory-proto v0.25.0-alpha.5 (/Users/djc/src/hickory-dns/crates/proto)
error[E0308]: mismatched types
   --> crates/proto/src/dnssec/crypto.rs:453:63
    |
453 |         let components = PublicKeyComponents::<Vec<u8>>::from(self.inner.public_key());
    |                          ------------------------------------ ^^^^^^^^^^^^^^^^^^^^^^^ expected `RsaPublicKeyComponents<Vec<...>>`, found `&RsaSubjectPublicKey`
    |                          |
    |                          arguments to this function are incorrect
    |
    = note: expected struct `PublicKeyComponents<Vec<u8>>`
            found reference `&RsaSubjectPublicKey`

ring's rsa::PublicKeyComponents offers a From<&PublicKey> impl, which we currently use in Hickory to convert the RSA public key to the DNSSEC-specified encoding (see /~https://github.com/hickory-dns/hickory-dns/blob/42d400f/crates/proto/src/dnssec/ring.rs#L453).

Minor issue:

ring deprecated RsaKeyPair::public_modulus_len() in favor of RsaKeyPair::public().modulus_len(). aws-lc-rs has not deprecated public_modulus_len() but also doesn't offer modulus_len() through its public(). For now, I just stuck an #[allow(deprecated)] on it but it might be nice to adopt the new ring API?

Requirements / Acceptance Criteria:

Would like to be able to merge support for aws-lc-rs into Hickory DNS.

[justsmth]

Hello -- Thanks for the PR!

I made a couple of adjustments to your PR. The modulus and exponent are only readily available with the "ring-io" feature enabled. I also added a modulus_len function to the RSA PublicKey.

Let us know if these changes address your needs.

[djc]

Looks great, thanks! If at all possible, would be nice to get a release containing these changes.

[justsmth]

Sure! There's a couple of other minor fixes that need to go out as well. I'll try to pull together a patch release. Maybe by tomorrow?

[djc]

Would be awesome!

[justsmth]

Hello! We just released aws-lc-rs v1.12.3. Thanks for the report and PR!

[djc]

Thanks for the quick response!