Cleanup which makes transcript optional, only required for multisig

crypto/dalek-ff-group/src/lib.rs

@@ -120,7 +120,9 @@ impl Field for Scalar {
   fn one() -> Self { Self(DScalar::one()) }
   fn square(&self) -> Self { *self * self }
   fn double(&self) -> Self { *self + self }
-  fn invert(&self) -> CtOption<Self> { CtOption::new(Self(self.0.invert()), Choice::from(1 as u8)) }
+  fn invert(&self) -> CtOption<Self> {
+    CtOption::new(Self(self.0.invert()), Choice::from(1 as u8))
+  }
   fn sqrt(&self) -> CtOption<Self> { unimplemented!() }
   fn is_zero(&self) -> Choice { Choice::from(if self.0 == DScalar::zero() { 1 } else { 0 }) }
   fn cube(&self) -> Self { *self * self * self }
@@ -137,7 +139,10 @@ impl PrimeField for Scalar {
   const CAPACITY: u32 = 252;
   fn from_repr(bytes: [u8; 32]) -> CtOption<Self> {
     let scalar = DScalar::from_canonical_bytes(bytes).map(|x| Scalar(x));
-    CtOption::new(scalar.unwrap_or(Scalar::zero()), Choice::from(if scalar.is_some() { 1 } else { 0 }))
+    CtOption::new(
+      scalar.unwrap_or(Scalar::zero()),
+      Choice::from(if scalar.is_some() { 1 } else { 0 })
+    )
   }
   fn to_repr(&self) -> [u8; 32] { self.0.to_bytes() }
 
@@ -285,7 +290,9 @@ impl EdwardsPoint {
 }
 
 pub struct EdwardsBasepointTable(pub DTable);
-pub const ED25519_BASEPOINT_TABLE: EdwardsBasepointTable = EdwardsBasepointTable(constants::ED25519_BASEPOINT_TABLE);
+pub const ED25519_BASEPOINT_TABLE: EdwardsBasepointTable = EdwardsBasepointTable(
+  constants::ED25519_BASEPOINT_TABLE
+);
 
 impl Deref for EdwardsBasepointTable {
     type Target = DTable;

crypto/frost/src/lib.rs

@@ -54,8 +54,8 @@ pub trait Curve: Clone + Copy + PartialEq + Eq + Debug {
   fn generator_table() -> Self::T;
 
   /// Multiexponentation function, presumably Straus or Pippenger
-  /// This library does provide an implementation of Straus which should increase key generation
-  /// performance by around 4x, also named multiexp_vartime, with the same API. However, if a more
+  /// This library does forward an implementation of Straus which should increase key generation
+  /// performance by around 4x, also named multiexp_vartime, with a similar API. However, if a more
   /// performant implementation is available, that should be used instead
   // This could also be written as -> Option<C::G> with None for not implemented
   fn multiexp_vartime(scalars: &[Self::F], points: &[Self::G]) -> Self::G;

crypto/transcript/src/lib.rs

@@ -16,7 +16,11 @@ pub trait Transcript {
   fn new(label: &'static [u8]) -> Self;
   fn append_message(&mut self, label: &'static [u8], message: &[u8]);
   fn challenge(&mut self, label: &'static [u8], len: usize) -> Vec<u8>;
-  fn seeded_rng(&self, label: &'static [u8], additional_entropy: Option<[u8; 32]>) -> Self::SeededRng;
+  fn seeded_rng(
+    &self,
+    label: &'static [u8],
+    additional_entropy: Option<[u8; 32]>
+  ) -> Self::SeededRng;
 }
 
 #[derive(Clone, Debug)]
@@ -40,15 +44,28 @@ impl<D: Digest> Transcript for DigestTranscript<D> {
     self.0.extend(label);
 
     let mut challenge = Vec::with_capacity(len);
-    challenge.extend(&D::new().chain_update(&self.0).chain_update(&0u64.to_le_bytes()).finalize());
+    challenge.extend(
+      &D::new()
+        .chain_update(&self.0)
+        .chain_update(&0u64.to_le_bytes()).finalize()
+    );
     for i in 0 .. (len / challenge.len()) {
-      challenge.extend(&D::new().chain_update(&self.0).chain_update(&u64::try_from(i).unwrap().to_le_bytes()).finalize());
+      challenge.extend(
+        &D::new()
+          .chain_update(&self.0)
+          .chain_update(&u64::try_from(i).unwrap().to_le_bytes())
+          .finalize()
+      );
     }
     challenge.truncate(len);
     challenge
   }
 
-  fn seeded_rng(&self, label: &'static [u8], additional_entropy: Option<[u8; 32]>) -> Self::SeededRng {
+  fn seeded_rng(
+    &self,
+    label: &'static [u8],
+    additional_entropy: Option<[u8; 32]>
+  ) -> Self::SeededRng {
     let mut transcript = DigestTranscript::<D>(self.0.clone(), PhantomData);
     if additional_entropy.is_some() {
       transcript.append_message(b"additional_entropy", &additional_entropy.unwrap());