Use proper messages for ValidatorSets/InInstructions pallet

Provides a DST, and associated metadata as beneficial.

Also utilizes MuSig's context to session-bind. Since set_keys_messages also
binds to set, this is semi-redundant, yet that's appreciated.

substrate/validator-sets/pallet/Cargo.toml

@@ -14,9 +14,6 @@ rustdoc-args = ["--cfg", "docsrs"]
 [dependencies]
 hashbrown = { version = "0.13", default-features = false }
 
-ciphersuite = { version = "0.3", path = "../../../crypto/ciphersuite", default-features = false, features = ["ristretto"] }
-dkg = { version = "0.4", path = "../../../crypto/dkg", default-features = false }
-
 scale = { package = "parity-scale-codec", version = "3", default-features = false, features = ["derive"] }
 scale-info = { version = "2", default-features = false, features = ["derive"] }
 
@@ -31,12 +28,12 @@ validator-sets-primitives = { path = "../primitives", default-features = false }
 
 [features]
 std = [
-  "ciphersuite/std",
-  "dkg/std",
-
   "scale/std",
   "scale-info/std",
 
+  "sp-core/std",
+  "sp-application-crypto/std",
+
   "frame-system/std",
   "frame-support/std",
 

substrate/validator-sets/pallet/src/lib.rs

@@ -69,23 +69,14 @@ pub mod pallet {
   #[pallet::genesis_build]
   impl<T: Config> GenesisBuild<T> for GenesisConfig<T> {
     fn build(&self) {
-      use ciphersuite::{group::GroupEncoding, Ciphersuite, Ristretto};
-
-      let hash_set = self.participants.iter().map(|key| key.0).collect::<hashbrown::HashSet<[u8; 32]>>();
-      if hash_set.len() != self.participants.len()
-      {
+      let hash_set =
+        self.participants.iter().map(|key| key.0).collect::<hashbrown::HashSet<[u8; 32]>>();
+      if hash_set.len() != self.participants.len() {
         panic!("participants contained duplicates");
       }
 
       let mut participants = Vec::new();
-      let mut keys = Vec::new();
       for participant in self.participants.clone() {
-        keys.push(
-          <Ristretto as Ciphersuite>::read_G::<&[u8]>(
-            &mut participant.0.as_ref(),
-          )
-          .expect("invalid participant"),
-        );
         participants.push((participant, self.bond));
       }
       let participants = BoundedVec::try_from(participants).unwrap();
@@ -99,7 +90,7 @@ pub mod pallet {
           Some(ValidatorSetData { bond: self.bond, network, participants: participants.clone() }),
         );
 
-        MuSigKeys::<T>::set(set, Some(Public(dkg::musig::musig_key::<Ristretto>(&keys).unwrap().to_bytes())));
+        MuSigKeys::<T>::set(set, Some(musig_key(set, &self.participants)));
         Pallet::<T>::deposit_event(Event::NewSet { set })
       }
     }
@@ -128,7 +119,7 @@ pub mod pallet {
       let Some(musig_key) = MuSigKeys::<T>::get(set) else {
         Err(Error::NonExistentValidatorSet)?
       };
-      if !musig_key.verify(&key_pair.encode(), signature) {
+      if !musig_key.verify(&set_keys_message(&set, key_pair), signature) {
         Err(Error::BadSignature)?;
       }
 
@@ -179,7 +170,9 @@ pub mod pallet {
       let set = ValidatorSet { session, network: *network };
       match Self::verify_signature(set, key_pair, signature) {
         Err(Error::AlreadyGeneratedKeys) => Err(InvalidTransaction::Stale)?,
-        Err(Error::NonExistentValidatorSet) | Err(Error::BadSignature) => Err(InvalidTransaction::BadProof)?,
+        Err(Error::NonExistentValidatorSet) | Err(Error::BadSignature) => {
+          Err(InvalidTransaction::BadProof)?
+        }
         Err(Error::__Ignore(_, _)) => unreachable!(),
         Ok(()) => (),
       }

substrate/validator-sets/primitives/Cargo.toml

@@ -14,15 +14,19 @@ rustdoc-args = ["--cfg", "docsrs"]
 [dependencies]
 zeroize = { version = "^1.5", features = ["derive"], optional = true }
 
+serde = { version = "1", features = ["derive"], optional = true }
+
+ciphersuite = { path = "../../../crypto/ciphersuite", version = "0.3", default-features = false, features = ["alloc", "ristretto"] }
+dkg = { path = "../../../crypto/dkg", version = "0.4", default-features = false }
+
 scale = { package = "parity-scale-codec", version = "3", default-features = false, features = ["derive", "max-encoded-len"] }
 scale-info = { version = "2", default-features = false, features = ["derive"] }
 
-serde = { version = "1", features = ["derive"], optional = true }
-
 sp-core = { git = "https://github.com/serai-dex/substrate", default-features = false }
+sp-std = { git = "https://github.com/serai-dex/substrate", default-features = false }
 
-serai-primitives = { path = "../..//primitives", default-features = false }
+serai-primitives = { path = "../../primitives", default-features = false }
 
 [features]
-std = ["zeroize", "scale/std", "scale-info/std", "serde", "sp-core/std", "serai-primitives/std"]
+std = ["zeroize", "serde", "ciphersuite/std", "dkg/std", "scale/std", "scale-info/std", "sp-core/std", "sp-std/std", "serai-primitives/std"]
 default = ["std"]

substrate/validator-sets/primitives/src/lib.rs

@@ -3,13 +3,17 @@
 #[cfg(feature = "std")]
 use zeroize::Zeroize;
 
-use scale::{Encode, Decode, MaxEncodedLen};
-use scale_info::TypeInfo;
-
 #[cfg(feature = "std")]
 use serde::{Serialize, Deserialize};
 
-use sp_core::{ConstU32, sr25519, bounded::BoundedVec};
+use ciphersuite::{group::GroupEncoding, Ciphersuite, Ristretto};
+
+use scale::{Encode, Decode, MaxEncodedLen};
+use scale_info::TypeInfo;
+
+use sp_core::{ConstU32, sr25519::Public, bounded::BoundedVec};
+#[cfg(not(feature = "std"))]
+use sp_std::vec::Vec;
 
 use serai_primitives::{NetworkId, Network, Amount};
 
@@ -37,13 +41,38 @@ pub struct ValidatorSetData {
 
   // Participant and their amount bonded to this set
   // Limit each set to 100 participants for now
-  pub participants: BoundedVec<(sr25519::Public, Amount), ConstU32<100>>,
+  pub participants: BoundedVec<(Public, Amount), ConstU32<100>>,
 }
 
 type MaxKeyLen = ConstU32<MAX_KEY_LEN>;
 /// The type representing a Key from an external network.
 pub type ExternalKey = BoundedVec<u8, MaxKeyLen>;
 
-/// A Validator Set's Ristretto key, used for signing InInstructions, and their key on the external
-/// network.
-pub type KeyPair = (sr25519::Public, ExternalKey);
+/// The key pair for a validator set.
+///
+/// This is their Ristretto key, used for signing Batches, and their key on the external network.
+pub type KeyPair = (Public, ExternalKey);
+
+/// The MuSig context for a validator set.
+pub fn musig_context(set: ValidatorSet) -> Vec<u8> {
+  [b"ValidatorSets-musig_key".as_ref(), &set.encode()].concat()
+}
+
+/// The MuSig public key for a validator set.
+///
+/// This function panics on invalid input.
+pub fn musig_key(set: ValidatorSet, set_keys: &[Public]) -> Public {
+  let mut keys = Vec::new();
+  for key in set_keys {
+    keys.push(
+      <Ristretto as Ciphersuite>::read_G::<&[u8]>(&mut key.0.as_ref())
+        .expect("invalid participant"),
+    );
+  }
+  Public(dkg::musig::musig_key::<Ristretto>(&musig_context(set), &keys).unwrap().to_bytes())
+}
+
+/// The message for the set_keys signature.
+pub fn set_keys_message(set: &ValidatorSet, key_pair: &KeyPair) -> Vec<u8> {
+  [b"ValidatorSets-key_pair".as_ref(), &(set, key_pair).encode()].concat()
+}