[DTLS] Add NamedCurve::P384

[ymtdzzz]

#24

[codecov]

Codecov Report

Merging #40 (9efdfa2) into master (f66d2e3) will decrease coverage by 0.06%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master      #40      +/-   ##
==========================================
- Coverage   67.56%   67.50%   -0.07%     
==========================================
  Files         143      143              
  Lines        8785     8793       +8     
  Branches     1858     1860       +2     
==========================================
  Hits         5936     5936              
- Misses       1228     1236       +8     
  Partials     1621     1621              

Impacted Files	Coverage Δ
dtls/src/curve/named_curve.rs	70.00% <0.00%> (-17.50%)	⬇️

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[ymtdzzz]

@rainliu
I'm implementing NamedCurve::P384 support with ring::agreement .
However, it doesn't support agreement with reusable keys, so I think we should wait for briansmith/ring#1081 to be merged.

Details

https://docs.rs/ring/0.16.19/ring/agreement/fn.agree_ephemeral.html

pub fn agree_ephemeral<B: AsRef<[u8]>, F, R, E>(
    my_private_key: EphemeralPrivateKey, 
    peer_public_key: &UnparsedPublicKey<B>, 
    error_value: E, 
    kdf: F
) -> Result<R, E> 
where
    F: FnOnce(&[u8]) -> Result<R, E>, 

Are there any alternatives?

[rainliu]

@zeroclock, what about alternative p384: https://docs.rs/p384/0.5.0/p384/ ?

I implement NamedCurve::P256 using p256. p384 should be similar.

[rainliu]

ops, looks like p384 doesn't have ecdh Elliptic Curve Diffie-Hellman (Ephemeral) Support

[ymtdzzz]

Thanks for your reply.
Yeah, p384 crate seems to support only ecdsa.
I’ll do more some research for now.

[rainliu]

close this PR. Please send PR To github.com/webrtc-rs/dtls repo