From c28f6a387cff5f9840f445e6e4b71ec7772188d6 Mon Sep 17 00:00:00 2001
From: David Craven <david@craven.ch>
Date: Mon, 4 Sep 2023 15:14:54 +0200
Subject: [PATCH] Improve api.

---
 frost-core/src/frost/keys.rs     | 54 +++++++++++++-------------------
 frost-core/src/frost/keys/dkg.rs |  8 ++---
 frost-core/src/verifying_key.rs  | 10 ++++++
 3 files changed, 36 insertions(+), 36 deletions(-)

diff --git a/frost-core/src/frost/keys.rs b/frost-core/src/frost/keys.rs
index 6e422df5..c8470f68 100644
--- a/frost-core/src/frost/keys.rs
+++ b/frost-core/src/frost/keys.rs
@@ -44,38 +44,6 @@ pub(crate) fn compute_group_commitment<C: Ciphersuite>(
     VerifiableSecretSharingCommitment(group_commitment)
 }
 
-/// Computes a verifying share for a peer given the group commitment.
-#[cfg_attr(feature = "internals", visibility::make(pub))]
-pub(crate) fn compute_verifying_share<C: Ciphersuite>(
-    group_commitment: &VerifiableSecretSharingCommitment<C>,
-    peer: Identifier<C>,
-) -> VerifyingShare<C> {
-    VerifyingShare(evaluate_vss(group_commitment, peer))
-}
-
-/// Computes the group public key given the group commitment.
-#[cfg_attr(feature = "internals", visibility::make(pub))]
-pub(crate) fn compute_public_key<C: Ciphersuite>(
-    group_commitment: &VerifiableSecretSharingCommitment<C>,
-) -> VerifyingKey<C> {
-    VerifyingKey {
-        element: group_commitment.coefficients()[0].value(),
-    }
-}
-
-/// Computes the public key package given a list of commitments.
-#[cfg_attr(feature = "internals", visibility::make(pub))]
-pub(crate) fn compute_public_key_package<C: Ciphersuite>(
-    members: &BTreeSet<Identifier<C>>,
-    group_commitment: &VerifiableSecretSharingCommitment<C>,
-) -> PublicKeyPackage<C> {
-    let mut verifying_keys = HashMap::new();
-    for peer in members {
-        verifying_keys.insert(*peer, compute_verifying_share(group_commitment, *peer));
-    }
-    PublicKeyPackage::new(verifying_keys, compute_public_key(group_commitment))
-}
-
 /// Return a vector of randomly generated polynomial coefficients ([`Scalar`]s).
 pub(crate) fn generate_coefficients<C: Ciphersuite, R: RngCore + CryptoRng>(
     size: usize,
@@ -226,6 +194,15 @@ where
     pub fn serialize(&self) -> <C::Group as Group>::Serialization {
         <C::Group as Group>::serialize(&self.0)
     }
+
+    /// Computes a verifying share for a peer given the group commitment.
+    #[cfg_attr(feature = "internals", visibility::make(pub))]
+    pub(crate) fn from_commitment(
+        commitment: &VerifiableSecretSharingCommitment<C>,
+        peer: Identifier<C>,
+    ) -> VerifyingShare<C> {
+        VerifyingShare(evaluate_vss(commitment, peer))
+    }
 }
 
 impl<C> Debug for VerifyingShare<C>
@@ -724,6 +701,19 @@ where
             ciphersuite: (),
         }
     }
+
+    /// Computes the public key package given a list of commitments.
+    #[cfg_attr(feature = "internals", visibility::make(pub))]
+    pub(crate) fn from_commitment(
+        members: &BTreeSet<Identifier<C>>,
+        commitment: &VerifiableSecretSharingCommitment<C>,
+    ) -> PublicKeyPackage<C> {
+        let mut verifying_keys = HashMap::new();
+        for peer in members {
+            verifying_keys.insert(*peer, VerifyingShare::from_commitment(commitment, *peer));
+        }
+        PublicKeyPackage::new(verifying_keys, VerifyingKey::from_commitment(commitment))
+    }
 }
 
 fn validate_num_of_signers<C: Ciphersuite>(
diff --git a/frost-core/src/frost/keys/dkg.rs b/frost-core/src/frost/keys/dkg.rs
index 5dd2ecb1..650e8343 100644
--- a/frost-core/src/frost/keys/dkg.rs
+++ b/frost-core/src/frost/keys/dkg.rs
@@ -40,9 +40,9 @@ use crate::{
 };
 
 use super::{
-    compute_group_commitment, compute_public_key_package, evaluate_polynomial,
-    generate_coefficients, generate_secret_polynomial, validate_num_of_signers, KeyPackage,
-    PublicKeyPackage, SecretShare, SigningShare, VerifiableSecretSharingCommitment,
+    compute_group_commitment, evaluate_polynomial, generate_coefficients,
+    generate_secret_polynomial, validate_num_of_signers, KeyPackage, PublicKeyPackage, SecretShare,
+    SigningShare, VerifiableSecretSharingCommitment,
 };
 
 /// DKG Round 1 structures.
@@ -454,7 +454,7 @@ pub fn part3<C: Ciphersuite>(
         .chain(iter::once(round2_secret_package.commitment.clone()))
         .collect();
     let group_commitment = compute_group_commitment(&commitments);
-    let public_key_package = compute_public_key_package(&members, &group_commitment);
+    let public_key_package = PublicKeyPackage::from_commitment(&members, &group_commitment);
     let key_package = KeyPackage {
         identifier: round2_secret_package.identifier,
         secret_share: signing_share,
diff --git a/frost-core/src/verifying_key.rs b/frost-core/src/verifying_key.rs
index 2932613e..273c594a 100644
--- a/frost-core/src/verifying_key.rs
+++ b/frost-core/src/verifying_key.rs
@@ -76,6 +76,16 @@ where
     pub fn verify(&self, msg: &[u8], signature: &Signature<C>) -> Result<(), Error<C>> {
         C::verify_signature(msg, signature, self)
     }
+
+    /// Computes the group public key given the group commitment.
+    #[cfg_attr(feature = "internals", visibility::make(pub))]
+    pub(crate) fn from_commitment(
+        commitment: &crate::frost::keys::VerifiableSecretSharingCommitment<C>,
+    ) -> VerifyingKey<C> {
+        VerifyingKey {
+            element: commitment.coefficients()[0].value(),
+        }
+    }
 }
 
 impl<C> Debug for VerifyingKey<C>