SIGMA-I Key Exchange (#378)

* Move `KeGroup` to `KeyExchange::Group`

- Introduce `KeyExchange::Hash`, which separates the OPRF hash from the one used in `KeyExchange`.
- Remove `De/Serialize` requirement on key exchange messages and states, which forced a lot of where bounds on downstream users.
- Rename `KeGroup` to `Group`.
- Replace `D` generic for hash with `H`.

* Use `voprf::derive_key()` directly

* Implement SIGMA-I key exchange

* Improve `KeyExchange` for SIGMA-I and Ed25519

* Implement EdDSA

* Un-qualify some method calls

* SIGMA-I: only include client identity in client mac

* SIGMA-I: include server mac in client signature

* Expose key exchange types in `crate` & move modules

* Implement Ed25519ph

* Document `ed25519` crate feature

* Remove `ristretto255-voprf` crate feature

* Adjust CI crate feature testing

* Fix Rustdoc

* Remove unnecessary generic parameters from SIGMA-I

* Properly mark to-do's with TODO

* Assorted fixes

* SIGMA-I: include context in signature

* SIGMA-I: include identifiers in signature

* Merge `ServerLoginStart/FinishParameters`

* Re-export more necessary types

* More carefully expose types

* Add ECDSA test

* SIGMA-I: share context hashing

* De-duplicate client static public key storage

* Hide `KeyExchange` better

* Use the correct hash in the root documentation

* Bump `derive-where`

* Format documentation examples a bit further

* Add remote OPRF seed documentation

* Rename `deserialize_key_pair` to `deserialize_take_key_pair`

* Add more key tests

* Remove `SharedSecret` trait

* SIGMA-I refactor message API

* Share more implementation between 3DH and SIGMA-I

* Remove unnecessary zero scalar check for Curve25519

* Use correct hash in test

* Add some more TODOs

* Exclude `tests` folder from Cargo publishing

* Enable missing dependencies

* Use right crate for testing Ed25519

* Remove unnecessary `Sized` constraints

* Remove unnecessary `ecdsa` crate features

* Move signature de/serialization to trait methods

* Nit: move import to appropriate location

* Add warning to SIGMA-I

benches/opaque.rs

@@ -23,16 +23,14 @@ struct Default;
 #[cfg(feature = "ristretto255")]
 impl CipherSuite for Default {
     type OprfCs = opaque_ke::Ristretto255;
-    type KeGroup = opaque_ke::Ristretto255;
-    type KeyExchange = opaque_ke::key_exchange::tripledh::TripleDh;
+    type KeyExchange = opaque_ke::TripleDh<opaque_ke::Ristretto255, sha2::Sha512>;
     type Ksf = opaque_ke::ksf::Identity;
 }
 
 #[cfg(not(feature = "ristretto255"))]
 impl CipherSuite for Default {
     type OprfCs = p256::NistP256;
-    type KeGroup = p256::NistP256;
-    type KeyExchange = opaque_ke::key_exchange::tripledh::TripleDh;
+    type KeyExchange = opaque_ke::TripleDh<p256::NistP256, sha2::Sha256>;
     type Ksf = opaque_ke::ksf::Identity;
 }
 
@@ -187,7 +185,7 @@ fn server_login_start_real(c: &mut Criterion) {
                 Some(password_file.clone()),
                 client_login_start_result.clone().message,
                 username,
-                ServerLoginStartParameters::default(),
+                ServerLoginParameters::default(),
             )
             .unwrap();
         })
@@ -209,7 +207,7 @@ fn server_login_start_fake(c: &mut Criterion) {
                 None,
                 client_login_start_result.clone().message,
                 username,
-                ServerLoginStartParameters::default(),
+                ServerLoginParameters::default(),
             )
             .unwrap();
         })
@@ -246,7 +244,7 @@ fn client_login_finish(c: &mut Criterion) {
         Some(password_file),
         client_login_start_result.clone().message,
         username,
-        ServerLoginStartParameters::default(),
+        ServerLoginParameters::default(),
     )
     .unwrap();
 
@@ -256,6 +254,7 @@ fn client_login_finish(c: &mut Criterion) {
                 .clone()
                 .state
                 .finish(
+                    &mut rng,
                     password,
                     server_login_start.clone().message,
                     ClientLoginFinishParameters::default(),
@@ -295,12 +294,13 @@ fn server_login_finish(c: &mut Criterion) {
         Some(password_file),
         client_login_start_result.clone().message,
         username,
-        ServerLoginStartParameters::default(),
+        ServerLoginParameters::default(),
     )
     .unwrap();
     let client_login_finish_result = client_login_start_result
         .state
         .finish(
+            &mut rng,
             password,
             server_login_start_result.clone().message,
             ClientLoginFinishParameters::default(),
@@ -312,7 +312,10 @@ fn server_login_finish(c: &mut Criterion) {
             server_login_start_result
                 .clone()
                 .state
-                .finish(client_login_finish_result.clone().message)
+                .finish(
+                    client_login_finish_result.clone().message,
+                    ServerLoginParameters::default(),
+                )
                 .unwrap();
         })
     });