Merge pull request #1961 from EspressoSystems/bf/new-cert-types

Create New Cert, Vote, and Vote Accumulator types

crates/types/src/lib.rs

@@ -21,6 +21,7 @@ pub mod message;
 pub mod traits;
 pub mod utils;
 pub mod vote;
+pub mod vote2;
 /// the type of consensus to run. Either:
 /// wait for a signal to start a view,
 /// or constantly run

crates/types/src/traits/election.rs

@@ -204,7 +204,7 @@ where
     fn genesis() -> Self;
 }
 
-/// A protocol for determining membership in and participating in a ccommittee.
+/// A protocol for determining membership in and participating in a committee.
 pub trait Membership<TYPES: NodeType>:
     Clone + Debug + Eq + PartialEq + Send + Sync + 'static
 {

crates/types/src/vote2.rs

@@ -0,0 +1,177 @@
+//! Vote, Accumulator, and Certificate Types
+
+use std::{
+    collections::{BTreeMap, HashMap},
+    marker::PhantomData,
+};
+
+use bincode::Options;
+use bitvec::vec::BitVec;
+use commit::CommitmentBounds;
+use either::Either;
+use ethereum_types::U256;
+use hotshot_utils::bincode::bincode_opts;
+use tracing::error;
+
+use crate::traits::{
+    election::Membership,
+    node_implementation::NodeType,
+    signature_key::{EncodedPublicKey, EncodedSignature, SignatureKey},
+};
+
+/// A simple vote that has a signer and commitment to the data voted on.
+pub trait Vote2<TYPES: NodeType> {
+    /// The membership of those that send this vote type
+    type Membership: Membership<TYPES>;
+    /// Type of data commitment this vote uses.
+    type Commitment: CommitmentBounds;
+
+    /// Get the signature of the vote sender
+    fn get_signature(&self) -> EncodedSignature;
+    /// Gets the Data commitment the vote references
+    fn get_data_commitment(&self) -> Self::Commitment;
+
+    /// Gets the public signature key of the votes creator/sender
+    fn get_signing_key(&self) -> TYPES::SignatureKey;
+    // fn create_signed_vote(Self::Commitment, Self::Membership) ??
+}
+
+/// Any type that is associated with a view
+pub trait ViewNumber<TYPES: NodeType> {
+    /// Returns the view number the type refers to.
+    fn get_view_number(&self) -> TYPES::Time;
+}
+
+/// The certificate formed from the collection of signatures a committee.
+/// The committee is defined by the `Membership` associated type.
+/// The votes all must be over the `Commitment` associated type.
+pub trait Certificate2<TYPES: NodeType> {
+    /// Type that defines membership for voters on the certificate
+    type Membership: Membership<TYPES>;
+    /// The data commitment this certificate certifies.
+    type Commitment: CommitmentBounds;
+
+    /// Build a certificate from the data commitment and the quorum of signers
+    fn create_signed_certificate(
+        data_commitment: Self::Commitment,
+        sig: <TYPES::SignatureKey as SignatureKey>::QCType,
+    ) -> Self;
+
+    /// Checks if the cert is valid
+    fn is_valid_cert(&self) -> bool;
+    /// Returns the amount of stake needed to create this certificate
+    // TODO: Make this a static ratio of the total stake of `Membership`
+    fn threshold() -> u64;
+    /// Get the data commitment the certificate is referencing
+    fn get_data_commitment(&self) -> Self::Commitment;
+}
+
+/// Accumulates votes until a certificate is formed.  This implementation works for all simple vote and certificate pairs
+pub struct VoteAccumulator2<
+    TYPES: NodeType,
+    VOTE: Vote2<TYPES>,
+    CERT: Certificate2<TYPES, Commitment = VOTE::Commitment>,
+> {
+    /// Map of all signatures accumlated so far
+    pub vote_outcomes: VoteMap2<VOTE::Commitment>,
+    /// A list of valid signatures for certificate aggregation
+    pub sig_lists: Vec<<TYPES::SignatureKey as SignatureKey>::PureAssembledSignatureType>,
+    /// A bitvec to indicate which node is active and send out a valid signature for certificate aggregation, this automatically do uniqueness check
+    pub signers: BitVec,
+    /// Phantom data to specify the types this accumulator is for
+    pub phantom: PhantomData<(TYPES, VOTE, CERT)>,
+}
+
+impl<
+        TYPES: NodeType,
+        VOTE: Vote2<TYPES>,
+        CERT: Certificate2<TYPES, Commitment = VOTE::Commitment>,
+    > VoteAccumulator2<TYPES, VOTE, CERT>
+{
+    /// Add a vote to the total accumulated votes.  Returns the accumulator or the certificate if we
+    /// have accumulated enough votes to exceed the threshold for creating a certificate.
+    #[allow(dead_code)]
+    fn accumulate(mut self, vote: &VOTE, membership: &VOTE::Membership) -> Either<Self, CERT> {
+        let key = vote.get_signing_key();
+
+        let vote_commitment = vote.get_data_commitment();
+        if !key.validate(
+            &vote.get_signature(),
+            &bincode_opts().serialize(&vote_commitment).unwrap(),
+        ) {
+            error!("Vote data is {:?}", vote.get_data_commitment());
+            error!("Invalid vote! Data");
+            return Either::Left(self);
+        }
+
+        // TODO: Lookup the actual stake
+        let stake_table_entry: <<TYPES as NodeType>::SignatureKey as SignatureKey>::StakeTableEntry = key.get_stake_table_entry(1u64);
+        let stake_table = membership.get_committee_qc_stake_table();
+        let vote_node_id = stake_table
+            .iter()
+            .position(|x| *x == stake_table_entry.clone())
+            .unwrap();
+
+        let encoded_key = key.to_bytes();
+
+        // Deserialize the signature so that it can be assembeld into a QC
+        // TODO ED Update this once we've gotten rid of EncodedSignature
+        let original_signature: <TYPES::SignatureKey as SignatureKey>::PureAssembledSignatureType =
+            bincode_opts()
+                .deserialize(&vote.get_signature().0)
+                .expect("Deserialization on the signature shouldn't be able to fail.");
+
+        let (total_stake_casted, total_vote_map) = self
+            .vote_outcomes
+            .entry(vote_commitment)
+            .or_insert_with(|| (0, BTreeMap::new()));
+
+        // Check for duplicate vote
+        // TODO ED Re-encoding signature key to bytes until we get rid of EncodedKey
+        // Have to do this because SignatureKey is not hashable
+        if total_vote_map.contains_key(&encoded_key) {
+            return Either::Left(self);
+        }
+
+        if self.signers.get(vote_node_id).as_deref() == Some(&true) {
+            error!("Node id is already in signers list");
+            return Either::Left(self);
+        }
+        self.signers.set(vote_node_id, true);
+        self.sig_lists.push(original_signature);
+
+        // TODO: Get the stake from the stake table entry.
+        *total_stake_casted += 1;
+        total_vote_map.insert(
+            encoded_key.clone(),
+            (vote.get_signature(), vote.get_data_commitment()),
+        );
+
+        if *total_stake_casted >= CERT::threshold() {
+            // Assemble QC
+            let real_qc_pp = <TYPES::SignatureKey as SignatureKey>::get_public_parameter(
+                stake_table.clone(),
+                U256::from(CERT::threshold()),
+            );
+
+            let real_qc_sig = <TYPES::SignatureKey as SignatureKey>::assemble(
+                &real_qc_pp,
+                self.signers.as_bitslice(),
+                &self.sig_lists[..],
+            );
+
+            let cert = CERT::create_signed_certificate(vote.get_data_commitment(), real_qc_sig);
+            return Either::Right(cert);
+        }
+        Either::Left(self)
+    }
+}
+
+/// Mapping of commitments to vote tokens by key.
+type VoteMap2<COMMITMENT> = HashMap<
+    COMMITMENT,
+    (
+        u64,
+        BTreeMap<EncodedPublicKey, (EncodedSignature, COMMITMENT)>,
+    ),
+>;