Remove SlashVote per #349

coordinator/tributary/src/tendermint/mod.rs

@@ -6,7 +6,7 @@ use async_trait::async_trait;
 use subtle::ConstantTimeEq;
 use zeroize::{Zeroize, Zeroizing};
 
-use rand::{SeedableRng, seq::SliceRandom, rngs::OsRng};
+use rand::{SeedableRng, seq::SliceRandom};
 use rand_chacha::ChaCha12Rng;
 
 use transcript::{Transcript, RecommendedTranscript};
@@ -43,11 +43,11 @@ use tokio::{
 use crate::{
   TENDERMINT_MESSAGE, TRANSACTION_MESSAGE, BLOCK_MESSAGE, ReadWrite,
   transaction::Transaction as TransactionTrait, Transaction, BlockHeader, Block, BlockError,
-  Blockchain, P2p, tendermint::tx::SlashVote,
+  Blockchain, P2p,
 };
 
 pub mod tx;
-use tx::{TendermintTx, VoteSignature};
+use tx::TendermintTx;
 
 const DST: &[u8] = b"Tributary Tendermint Commit Aggregator";
 
@@ -312,21 +312,17 @@ impl<D: Db, T: TransactionTrait, P: P2p> Network for TendermintNetwork<D, T, P>
     );
 
     let signer = self.signer();
-    let tx = match slash_event {
+    let Some(tx) = (match slash_event {
       SlashEvent::WithEvidence(m1, m2) => {
         // create an unsigned evidence tx
-        TendermintTx::SlashEvidence((m1, m2).encode())
+        Some(TendermintTx::SlashEvidence((m1, m2).encode()))
       }
-      SlashEvent::Id(reason, block, round) => {
-        // create a signed vote tx
-        let mut tx = TendermintTx::SlashVote(SlashVote {
-          id: (reason, block, round).encode().try_into().unwrap(),
-          target: validator.encode().try_into().unwrap(),
-          sig: VoteSignature::default(),
-        });
-        tx.sign(&mut OsRng, signer.genesis, &signer.key);
-        tx
+      SlashEvent::Id(_reason, _block, _round) => {
+        // TODO: Increase locally observed slash points
+        None
       }
+    }) else {
+      return;
     };
 
     // add tx to blockchain and broadcast to peers

coordinator/tributary/src/tendermint/tx.rs

@@ -1,19 +1,10 @@
-use core::ops::Deref;
-use std::{io, vec, default::Default};
+use std::io;
 
 use scale::Decode;
 
-use zeroize::Zeroizing;
+use blake2::{Digest, Blake2s256};
 
-use blake2::{Digest, Blake2s256, Blake2b512};
-
-use rand::{RngCore, CryptoRng};
-
-use ciphersuite::{
-  group::{GroupEncoding, ff::Field},
-  Ciphersuite, Ristretto,
-};
-use schnorr::SchnorrSignature;
+use ciphersuite::{Ciphersuite, Ristretto};
 
 use crate::{
   transaction::{Transaction, TransactionKind, TransactionError},
@@ -28,72 +19,10 @@ use tendermint::{
   ext::{Network, Commit, RoundNumber, SignatureScheme},
 };
 
-/// Signing data for a slash vote.
-///
-/// The traditional Signed uses a nonce, whereas votes aren't required/expected to be ordered.
-/// Accordingly, a simple uniqueness check works instead.
-#[derive(Clone, PartialEq, Eq, Debug)]
-pub struct VoteSignature {
-  pub signer: <Ristretto as Ciphersuite>::G,
-  pub signature: SchnorrSignature<Ristretto>,
-}
-
-impl ReadWrite for VoteSignature {
-  fn read<R: io::Read>(reader: &mut R) -> io::Result<Self> {
-    let signer = Ristretto::read_G(reader)?;
-    let signature = SchnorrSignature::<Ristretto>::read(reader)?;
-
-    Ok(VoteSignature { signer, signature })
-  }
-
-  fn write<W: io::Write>(&self, writer: &mut W) -> io::Result<()> {
-    writer.write_all(&self.signer.to_bytes())?;
-    self.signature.write(writer)
-  }
-}
-
-impl Default for VoteSignature {
-  fn default() -> Self {
-    VoteSignature {
-      signer: Ristretto::generator(),
-      signature: SchnorrSignature::<Ristretto>::read(&mut [0; 64].as_slice()).unwrap(),
-    }
-  }
-}
-
-/// A vote to slash a malicious validator.
-#[derive(Clone, PartialEq, Eq, Debug)]
-pub struct SlashVote {
-  pub id: [u8; 13],       // vote id(slash event id)
-  pub target: [u8; 32],   // who to slash
-  pub sig: VoteSignature, // signature
-}
-
-impl ReadWrite for SlashVote {
-  fn read<R: io::Read>(reader: &mut R) -> io::Result<Self> {
-    let mut id = [0; 13];
-    let mut target = [0; 32];
-    reader.read_exact(&mut id)?;
-    reader.read_exact(&mut target)?;
-    let sig = VoteSignature::read(reader)?;
-
-    Ok(SlashVote { id, target, sig })
-  }
-
-  fn write<W: io::Write>(&self, writer: &mut W) -> io::Result<()> {
-    writer.write_all(&self.id)?;
-    writer.write_all(&self.target)?;
-    self.sig.write(writer)
-  }
-}
-
 #[allow(clippy::large_enum_variant)]
 #[derive(Clone, PartialEq, Eq, Debug)]
 pub enum TendermintTx {
   SlashEvidence(Vec<u8>),
-  // TODO: should the SlashVote.sig be directly in the enum
-  // like as in (SlashVote, sig) since the sig is sig of the tx.
-  SlashVote(SlashVote),
 }
 
 impl ReadWrite for TendermintTx {
@@ -126,10 +55,6 @@ impl ReadWrite for TendermintTx {
         }
         Ok(TendermintTx::SlashEvidence(data))
       }
-      1 => {
-        let vote = SlashVote::read(reader)?;
-        Ok(TendermintTx::SlashVote(vote))
-      }
       _ => Err(io::Error::new(io::ErrorKind::Other, "invalid transaction type")),
     }
   }
@@ -141,10 +66,6 @@ impl ReadWrite for TendermintTx {
         writer.write_all(&u32::try_from(ev.len()).unwrap().to_le_bytes())?;
         writer.write_all(ev)
       }
-      TendermintTx::SlashVote(vote) => {
-        writer.write_all(&[1])?;
-        vote.write(writer)
-      }
     }
   }
 }
@@ -157,32 +78,12 @@ impl Transaction for TendermintTx {
   }
 
   fn hash(&self) -> [u8; 32] {
-    let mut tx = self.serialize();
-    if let TendermintTx::SlashVote(vote) = self {
-      // Make sure the part we're cutting off is the signature
-      assert_eq!(tx.drain((tx.len() - 64) ..).collect::<Vec<_>>(), vote.sig.signature.serialize());
-    }
-    Blake2s256::digest(tx).into()
+    Blake2s256::digest(self.serialize()).into()
   }
 
-  fn sig_hash(&self, genesis: [u8; 32]) -> <Ristretto as Ciphersuite>::F {
+  fn sig_hash(&self, _genesis: [u8; 32]) -> <Ristretto as Ciphersuite>::F {
     match self {
       TendermintTx::SlashEvidence(_) => panic!("sig_hash called on slash evidence transaction"),
-      TendermintTx::SlashVote(vote) => {
-        let signature = &vote.sig.signature;
-        <Ristretto as Ciphersuite>::F::from_bytes_mod_order_wide(
-          &Blake2b512::digest(
-            [
-              b"Tributary Slash Vote",
-              genesis.as_ref(),
-              &self.hash(),
-              signature.R.to_bytes().as_ref(),
-            ]
-            .concat(),
-          )
-          .into(),
-        )
-      }
     }
   }
 
@@ -191,34 +92,6 @@ impl Transaction for TendermintTx {
   }
 }
 
-impl TendermintTx {
-  // Sign a transaction
-  pub fn sign<R: RngCore + CryptoRng>(
-    &mut self,
-    rng: &mut R,
-    genesis: [u8; 32],
-    key: &Zeroizing<<Ristretto as Ciphersuite>::F>,
-  ) {
-    fn signature(tx: &mut TendermintTx) -> Option<&mut VoteSignature> {
-      match tx {
-        TendermintTx::SlashVote(vote) => Some(&mut vote.sig),
-        _ => None,
-      }
-    }
-
-    signature(self).unwrap().signer = Ristretto::generator() * key.deref();
-
-    let sig_nonce = Zeroizing::new(<Ristretto as Ciphersuite>::F::random(rng));
-    signature(self).unwrap().signature.R =
-      <Ristretto as Ciphersuite>::generator() * sig_nonce.deref();
-
-    let sig_hash = self.sig_hash(genesis);
-
-    signature(self).unwrap().signature =
-      SchnorrSignature::<Ristretto>::sign(key, sig_nonce, sig_hash);
-  }
-}
-
 pub fn decode_evidence<N: Network>(
   mut ev: &[u8],
 ) -> Result<(SignedMessageFor<N>, Option<SignedMessageFor<N>>), TransactionError> {
@@ -234,13 +107,13 @@ pub fn decode_evidence<N: Network>(
 // re-implements an entire foreign library's checks for malicious behavior).
 pub(crate) fn verify_tendermint_tx<N: Network>(
   tx: &TendermintTx,
-  genesis: [u8; 32],
   schema: N::SignatureScheme,
   commit: impl Fn(u32) -> Option<Commit<N::SignatureScheme>>,
 ) -> Result<(), TransactionError> {
   tx.verify()?;
 
   match tx {
+    // TODO: Only allow one evidence per validator, since evidence is fatal
     TendermintTx::SlashEvidence(ev) => {
       let (first, second) = decode_evidence::<N>(ev)?;
 
@@ -332,21 +205,6 @@ pub(crate) fn verify_tendermint_tx<N: Network>(
         _ => Err(TransactionError::InvalidContent)?,
       }
     }
-    TendermintTx::SlashVote(vote) => {
-      // TODO: verify the target is actually one of our validators?
-      // this shouldn't be a problem because if the target isn't valid, no one else
-      // gonna vote on it. But we still have to think about spam votes.
-
-      // TODO: we need to check signer is a participant
-
-      // TODO: Move this into the standalone TendermintTx verify
-      let sig = &vote.sig;
-      // verify the tx signature
-      // TODO: Use Schnorr half-aggregation and a batch verification here
-      if !sig.signature.verify(sig.signer, tx.sig_hash(genesis)) {
-        Err(TransactionError::InvalidSignature)?;
-      }
-    }
   }
 
   Ok(())