Fix multiple TODOs

src/experimental/bit.rs

@@ -205,9 +205,9 @@ where
     type M = Message;
     type PKG = PublicKey<E>;
 
-    type PKnM = ::core::iter::Once<(Message, PublicKey<E>)>;
-
-    fn messages_and_publickeys(self) -> Self::PKnM {
+    fn messages_and_publickeys(
+        self,
+    ) -> impl Iterator<Item = (Message, PublicKey<E>)> + ExactSizeIterator {
         let mut publickey = E::PublicKeyGroup::zero();
         for i in 0..8 * self.signers.borrow().len() {
             if self.signers.borrow()[i / 8] & (1 << (i % 8)) != 0 {
@@ -380,9 +380,9 @@ where
     type M = Message;
     type PKG = PublicKey<E>;
 
-    type PKnM = ::core::iter::Once<(Message, PublicKey<E>)>;
-
-    fn messages_and_publickeys(self) -> Self::PKnM {
+    fn messages_and_publickeys(
+        self,
+    ) -> impl Iterator<Item = (Message, PublicKey<E>)> + ExactSizeIterator {
         let mut publickey = E::PublicKeyGroup::zero();
         for signers in self.signers.iter().rev().map(|signers| signers.borrow()) {
             publickey.double_in_place();
@@ -659,8 +659,7 @@ mod tests {
         }
         assert!(bitsig1.merge(&bitsig2).is_err());
 
-        let mut multimsg =
-            crate::pop_aggregator::SignatureAggregatorAssumingPoP::<ZBLS>::new();
+        let mut multimsg = crate::pop_aggregator::SignatureAggregatorAssumingPoP::<ZBLS>::new();
         multimsg.aggregate(&bitsig1);
         multimsg.aggregate(&bitsig2);
         assert!(multimsg.verify()); // verifiers::verify_with_distinct_messages(&dms,true)

src/experimental/delinear.rs

@@ -63,9 +63,10 @@ impl<'a, E: EngineBLS> Signed for &'a Delinearized<E> {
 
     type M = &'a Message;
     type PKG = &'a PublicKey<Self::E>;
-    type PKnM = ::std::collections::hash_map::Iter<'a, Message, PublicKey<E>>;
 
-    fn messages_and_publickeys(self) -> Self::PKnM {
+    fn messages_and_publickeys(
+        self,
+    ) -> impl Iterator<Item = (&'a Message, &'a PublicKey<E>)> + ExactSizeIterator {
         self.messages_n_publickeys.iter()
     }
 

src/experimental/distinct.rs

@@ -81,9 +81,10 @@ impl<'a, E: EngineBLS> Signed for &'a DistinctMessages<E> {
 
     type M = &'a Message;
     type PKG = &'a PublicKey<Self::E>;
-    type PKnM = ::std::collections::hash_map::Iter<'a, Message, PublicKey<E>>;
 
-    fn messages_and_publickeys(self) -> Self::PKnM {
+    fn messages_and_publickeys(
+        self,
+    ) -> impl Iterator<Item = (&'a Message, &'a PublicKey<E>)> + ExactSizeIterator {
         self.messages_n_publickeys.iter()
     }
 

src/lib.rs

@@ -91,7 +91,6 @@
 #[cfg(doctest)]
 pub struct ReadmeDoctests;
 
-
 extern crate ark_serialize;
 extern crate ark_serialize_derive;
 
@@ -161,7 +160,9 @@ impl<E: EngineBLS> GeneralizedBLSPublicKey<E> for PublicKey<E> {
     }
 }
 
-impl<E: EngineBLS> GeneralizedBLSPublicKey<E> for (PublicKey<E>, nugget::PublicKeyInSignatureGroup<E>) {
+impl<E: EngineBLS> GeneralizedBLSPublicKey<E>
+    for (PublicKey<E>, nugget::PublicKeyInSignatureGroup<E>)
+{
     fn public_key(&self) -> PublicKey<E> {
         self.0
     }
@@ -295,29 +296,20 @@ impl<'a> From<&'a [u8]> for Message {
 /// We shall make `messages_and_publickeys` take `&sefl` and
 /// remove these limitations in the future once ATCs stabalize,
 /// thus removing `PKG`.  See [Rust RFC 1598](https://github.com/rust-lang/rfcs/blob/master/text/1598-generic_associated_types.md)
-/// We shall eventually remove MnPK entirely whenever `-> impl Trait`
-/// in traits gets stabalized.  See [Rust RFCs 1522, 1951, and 2071](https://github.com/rust-lang/rust/issues/34511
 pub trait Signed: Sized {
     type E: EngineBLS;
 
     /// Return the aggregated signature
     fn signature(&self) -> Signature<Self::E>;
 
-    type M: Borrow<Message>; // = Message;
-    type PKG: GeneralizedBLSPublicKey<Self::E>; // = PublicKey<Self::E>;
-
-    /// Iterator over, messages and public key reference pairs.
-    type PKnM: Iterator<Item = (Self::M, Self::PKG)> + ExactSizeIterator;
-    // type PKnM<'a>: Iterator<Item = (
-    //    &'a <<Self as Signed<'a>>::E as EngineBLS>::PublicKeyGroup,
-    //    &'a Self::M,
-    // )> + DoubleEndedIterator + ExactSizeIterator + 'a;
+    type M: Borrow<Message>;
+    type PKG: GeneralizedBLSPublicKey<Self::E>;
 
     /// Returns an iterator over messages and public key reference for
     /// pairings, often only partially aggregated.
-    fn messages_and_publickeys(self) -> Self::PKnM;
-    // fn messages_and_publickeys<'a>(&'s self) -> PKnM<'a>
-    // -> impl Iterator<Item = (&'a Self::M, &'a Self::E::PublicKeyGroup)> + 'a;
+    fn messages_and_publickeys(
+        self,
+    ) -> impl Iterator<Item = (Self::M, Self::PKG)> + ExactSizeIterator;
 
     /// Appropriate BLS signature verification for the `Self` type.
     ///

src/nugget.rs

@@ -21,9 +21,9 @@ use digest::FixedOutputReset;
 use sha2::Sha256;
 
 use crate::broken_derives;
+use crate::chaum_pedersen_signature::DLEQProof;
 use crate::chaum_pedersen_signature::{ChaumPedersenSigner, ChaumPedersenVerifier};
 use crate::dual_scalar_mul::DualScalarMultiplication;
-use crate::chaum_pedersen_signature::DLEQProof;
 use crate::serialize::SerializableToBytes;
 use crate::single::{Keypair, KeypairVT, PublicKey, SecretKey, SecretKeyVT, Signature};
 use crate::{EngineBLS, Message, Signed};
@@ -34,8 +34,6 @@ use crate::{EngineBLS, Message, Signed};
 pub struct PublicKeyInSignatureGroup<E: EngineBLS>(pub E::SignatureGroup);
 broken_derives!(PublicKeyInSignatureGroup); // Actually the derive works for this one, not sure why.
 
-//TODO: Make a type for a sister group. This makes sense because SisterGroup it doesn't mean on itself
-// SisterGroup<E: EngineBLS> = CurveGroup + PrimeGroup<ScalarField = E::Scalar> + SerializableToBytes
 /// Wrapper for a point in the third curve sister group which is supposed to
 /// have the same logarithm as the public key in the public key group
 #[derive(Debug, Clone, Copy, PartialEq, Eq, CanonicalDeserialize)]
@@ -238,10 +236,10 @@ where
     type M = Message;
     type PKG = PublicKey<E>;
 
-    type PKnM = ::core::iter::Once<(Message, PublicKey<E>)>;
-
-    fn messages_and_publickeys(self) -> Self::PKnM {
-        once((self.message.clone(), self.publickey.into_bls_public_key())) // TODO:  Avoid clone
+    fn messages_and_publickeys(
+        self,
+    ) -> impl Iterator<Item = (Message, PublicKey<E>)> + ExactSizeIterator {
+        once((self.message.clone(), self.publickey.into_bls_public_key()))
     }
 
     fn signature(&self) -> Signature<E> {