Adding CipherSuite trait to handle bundling of underlying crypto primitives

src/ciphersuite.rs

@@ -1,6 +1,30 @@
+// Copyright (c) Facebook, Inc. and its affiliates.
+//
+// This source code is licensed under the MIT license found in the
+// LICENSE file in the root directory of this source tree.
 
+//! Defines the CipherSuite trait to specify the underlying primitives for OPAQUE
+
+use crate::{
+    errors::InternalPakeError,
+    group::Group,
+    keypair::{Key, KeyPair},
+    slow_hash::SlowHash,
+};
+use generic_array::typenum::{U32, U64};
+use rand_core::{CryptoRng, RngCore};
+
+/// Configures the underlying primitives used in OPAQUE
 pub trait CipherSuite {
-    type Aead;
-    type Group;
-    type Keypair;
+    type Aead: aead::NewAead<KeySize = U32> + aead::Aead;
+    type Group: Group<ScalarLen = U32, UniformBytesLen = U64>;
+    type KeyFormat: KeyPair<Repr = Key> + PartialEq;
+    type SlowHash: SlowHash;
+
+    /// Generating a random key pair given a cryptographic rng
+    fn generate_random_keypair<R: RngCore + CryptoRng>(
+        rng: &mut R,
+    ) -> Result<Self::KeyFormat, InternalPakeError> {
+        Self::KeyFormat::generate_random(rng)
+    }
 }