Merge weights and signing scheme into validators, documenting needed changes

substrate/consensus/src/validators.rs

@@ -0,0 +1,67 @@
+// TODO: This should be built around pallet_sessions (and pallet_staking?).
+
+use sp_application_crypto::{
+  RuntimePublic as PublicTrait, Pair as PairTrait,
+  sr25519::{Public, Pair, Signature},
+};
+
+use tendermint_machine::ext::{BlockNumber, Round, Weights, SignatureScheme};
+
+const VALIDATORS: usize = 1;
+
+pub(crate) struct TendermintValidators {
+  keys: Pair, // sp_keystore
+  lookup: Vec<Public>, // sessions
+}
+
+impl TendermintValidators {
+  pub(crate) fn new() -> TendermintValidators {
+    let keys = Pair::from_string("//Alice", None).unwrap();
+    TendermintValidators { lookup: vec![keys.public()], keys }
+  }
+}
+
+impl SignatureScheme for TendermintValidators {
+  type ValidatorId = u16;
+  type Signature = Signature;
+  type AggregateSignature = Vec<Signature>;
+
+  fn sign(&self, msg: &[u8]) -> Signature {
+    self.keys.sign(msg)
+  }
+
+  fn verify(&self, validator: u16, msg: &[u8], sig: &Signature) -> bool {
+    self.lookup[usize::try_from(validator).unwrap()].verify(&msg, sig)
+  }
+
+  fn aggregate(sigs: &[Signature]) -> Vec<Signature> {
+    sigs.to_vec()
+  }
+
+  fn verify_aggregate(&self, validators: &[u16], msg: &[u8], sigs: &Vec<Signature>) -> bool {
+    if validators.len() != sigs.len() {
+      return false;
+    }
+    for (v, sig) in validators.iter().zip(sigs.iter()) {
+      if !self.verify(*v, msg, sig) {
+        return false;
+      }
+    }
+    true
+  }
+}
+
+impl Weights for TendermintValidators {
+  type ValidatorId = u16;
+
+  fn total_weight(&self) -> u64 {
+    VALIDATORS.try_into().unwrap()
+  }
+  fn weight(&self, id: u16) -> u64 {
+    [1; VALIDATORS][usize::try_from(id).unwrap()]
+  }
+
+  fn proposer(&self, number: BlockNumber, round: Round) -> u16 {
+    u16::try_from((number.0 + u64::from(round.0)) % u64::try_from(VALIDATORS).unwrap()).unwrap()
+  }
+}