Merge pull request #1 from EIPs-CodeLab/feat/bls-signing

Add BLS verification and signing roots for bids, envelopes, and PTC

Author: zacksfF

Cargo.lock

@@ -21,7 +21,6 @@ path = "examples/ptc_sim/main.rs"
 
 [dependencies]
 ssz_types   = "0.6"
-tree_hash   = "0.6"
 blst        = "0.3"
 sha2        = "0.10"
 hex         = "0.4"
@@ -39,4 +38,4 @@ criterion   = "0.5"
 
 [profile.release]
 opt-level = 3
-lto       = true
+lto       = true

Cargo.toml

@@ -1,7 +1,7 @@
-use crate::beacon_chain::constants::MAX_PAYLOAD_ATTESTATIONS;
 /// EIP-7732 — SSZ containers
 /// All containers directly mirror the spec definitions.
 /// Reference: https://eips.ethereum.org/EIPS/eip-7732#containers
+use crate::beacon_chain::constants::MAX_PAYLOAD_ATTESTATIONS;
 use crate::beacon_chain::types::*;
 use serde::{Deserialize, Serialize};
 

src/beacon_chain/containers.rs

@@ -5,10 +5,11 @@
 ///
 /// Reference: https://eips.ethereum.org/EIPS/eip-7732#beacon-chain-changes
 use crate::beacon_chain::{
-    constants::PTC_SIZE,
+    constants::{DOMAIN_PTC_ATTESTER, PTC_SIZE},
     containers::{PayloadAttestation, PayloadAttestationData},
-    types::{Slot, ValidatorIndex},
+    types::{BLSPubkey, Slot, ValidatorIndex},
 };
+use crate::utils::{crypto, ssz};
 use thiserror::Error;
 
 #[derive(Debug, Error)]
@@ -24,11 +25,15 @@ pub enum PayloadAttestationError {
 
     #[error("Attesting index {0} is not a PTC member for this slot")]
     NotPtcMember(ValidatorIndex),
+
+    #[error("PTC pubkey list length does not match committee size")]
+    MissingPubkeys,
 }
 
 pub trait BeaconStateRead {
     fn parent_slot(&self) -> Slot;
     fn get_ptc(&self, slot: Slot) -> Vec<ValidatorIndex>;
+    fn ptc_pubkeys(&self, slot: Slot) -> Vec<BLSPubkey>;
     fn parent_beacon_block_root(&self) -> [u8; 32];
 }
 
@@ -66,28 +71,40 @@ pub fn process_payload_attestation<S: BeaconStateRead>(
 
     // Get the PTC members for the attested slot
     let ptc = state.get_ptc(data.slot);
+    let ptc_pubkeys = state.ptc_pubkeys(data.slot);
+    if ptc_pubkeys.len() != ptc.len() {
+        return Err(PayloadAttestationError::MissingPubkeys);
+    }
 
-    // Collect attesting validators
-    let attesting: Vec<ValidatorIndex> = attestation
-        .aggregation_bits
-        .iter()
-        .enumerate()
-        .filter(|(_, &bit)| bit)
-        .map(|(i, _)| ptc[i])
-        .collect();
+    // Collect attesting validators and their pubkeys
+    let mut attesting_indices = Vec::new();
+    let mut attesting_pubkeys = Vec::new();
+    for (i, bit) in attestation.aggregation_bits.iter().enumerate() {
+        if *bit {
+            attesting_indices.push(ptc[i]);
+            attesting_pubkeys.push(ptc_pubkeys[i]);
+        }
+    }
 
-    // Verify aggregated signature (stub)
-    verify_aggregate_ptc_signature(&attestation.signature, data, &attesting)?;
+    // Verify aggregated signature
+    verify_aggregate_ptc_signature(
+        &attestation.signature,
+        data,
+        &attesting_indices,
+        &attesting_pubkeys,
+    )?;
 
     Ok(())
 }
 
 fn verify_aggregate_ptc_signature(
-    _signature: &[u8; 96],
-    _data: &PayloadAttestationData,
+    signature: &[u8; 96],
+    data: &PayloadAttestationData,
     _validators: &[ValidatorIndex],
+    pubkeys: &[BLSPubkey],
 ) -> Result<(), PayloadAttestationError> {
-    // TODO: aggregate public keys, compute signing_root with DOMAIN_PTC_ATTESTER,
-    //       verify with blst
-    Ok(())
+    let domain = ssz::compute_domain_simple(DOMAIN_PTC_ATTESTER);
+    let signing_root = ssz::signing_root(data, domain);
+    crypto::bls_verify_aggregate(pubkeys, &signing_root, signature)
+        .map_err(|_| PayloadAttestationError::InvalidSignature)
 }

src/beacon_chain/process_payload_attestation.rs

@@ -7,9 +7,11 @@
 ///
 /// Reference: https://eips.ethereum.org/EIPS/eip-7732#beacon-chain-changes
 use crate::beacon_chain::{
+    constants::DOMAIN_BEACON_BUILDER,
     containers::{BuilderPendingPayment, BuilderPendingWithdrawal, SignedExecutionPayloadBid},
-    types::{BuilderIndex, Gwei, Slot},
+    types::{BLSPubkey, BuilderIndex, Gwei, Slot},
 };
+use crate::utils::{crypto, ssz};
 use thiserror::Error;
 
 #[derive(Debug, Error)]
@@ -28,11 +30,15 @@ pub enum PayloadBidError {
 
     #[error("Parent block hash mismatch")]
     ParentHashMismatch,
+
+    #[error("Builder pubkey missing for index {0}")]
+    MissingPubkey(BuilderIndex),
 }
 
 /// Minimal beacon state surface needed by this function.
 pub trait BeaconStateMut {
     fn builder_balance(&self, index: BuilderIndex) -> Option<Gwei>;
+    fn builder_pubkey(&self, index: BuilderIndex) -> Option<BLSPubkey>;
     fn deduct_builder_balance(&mut self, index: BuilderIndex, amount: Gwei);
     fn push_pending_payment(&mut self, payment: BuilderPendingPayment);
     fn current_slot(&self) -> Slot;
@@ -68,10 +74,7 @@ pub fn process_execution_payload_bid<S: BeaconStateMut>(
         return Err(PayloadBidError::ParentHashMismatch);
     }
 
-    // Step 3 — BLS signature (stub — wire to blst crate in full impl)
-    verify_builder_signature(signed_bid)?;
-
-    // Step 4 + 5 — balance check and deduction
+    // Step 3 — balance check
     let balance = state
         .builder_balance(bid.builder_index)
         .ok_or(PayloadBidError::BuilderNotFound(bid.builder_index))?;
@@ -83,6 +86,10 @@ pub fn process_execution_payload_bid<S: BeaconStateMut>(
         });
     }
 
+    // Step 4 — BLS signature
+    verify_builder_signature(state, signed_bid)?;
+
+    // Step 5 — deduct balance
     state.deduct_builder_balance(bid.builder_index, bid.value);
 
     // Step 6 — queue pending payment
@@ -100,9 +107,17 @@ pub fn process_execution_payload_bid<S: BeaconStateMut>(
 }
 
 /// Stub — replace with blst domain-separated BLS verify in full impl.
-fn verify_builder_signature(
-    _signed_bid: &SignedExecutionPayloadBid,
+fn verify_builder_signature<S: BeaconStateMut>(
+    state: &S,
+    signed_bid: &SignedExecutionPayloadBid,
 ) -> Result<(), PayloadBidError> {
-    // TODO: compute signing_root with DOMAIN_BEACON_BUILDER and verify
-    Ok(())
+    let message = &signed_bid.message;
+    let pk = state
+        .builder_pubkey(message.builder_index)
+        .ok_or(PayloadBidError::MissingPubkey(message.builder_index))?;
+
+    let domain = ssz::compute_domain_simple(DOMAIN_BEACON_BUILDER);
+    let signing_root = ssz::signing_root(message, domain);
+    crypto::bls_verify(&pk, &signing_root, &signed_bid.signature)
+        .map_err(|_| PayloadBidError::InvalidSignature)
 }

src/beacon_chain/process_payload_bid.rs

@@ -11,11 +11,13 @@
 ///
 /// Reference: https://eips.ethereum.org/EIPS/eip-7732#honest-builder-guide
 use crate::beacon_chain::{
+    constants::DOMAIN_BEACON_BUILDER,
     containers::{ExecutionPayloadBid, SignedExecutionPayloadBid},
     types::{
         BLSSignature, BuilderIndex, ExecutionAddress, Gwei, Hash32, KZGCommitment, Root, Slot,
     },
 };
+use crate::utils::ssz;
 use thiserror::Error;
 
 #[derive(Debug, Error)]
@@ -88,20 +90,14 @@ pub fn construct_bid(
         blob_kzg_commitments: params.blob_kzg_commitments.clone(),
     };
 
-    // Compute signing root: hash_tree_root(message) XOR domain
-    let signing_root = compute_signing_root(&message);
+    let domain = ssz::compute_domain_simple(DOMAIN_BEACON_BUILDER);
+    let signing_root = ssz::signing_root(&message, domain);
 
     let signature = sign_fn(&signing_root).map_err(BidError::SigningFailed)?;
 
     Ok(SignedExecutionPayloadBid { message, signature })
 }
 
-/// Stub signing root — replace with proper SSZ hash_tree_root + domain mix.
-fn compute_signing_root(_message: &ExecutionPayloadBid) -> Vec<u8> {
-    // TODO: ssz hash_tree_root(message) XOR compute_domain(DOMAIN_BEACON_BUILDER, ...)
-    vec![0u8; 32]
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;

src/builder/bid.rs

@@ -13,11 +13,13 @@
 ///
 /// Reference: https://eips.ethereum.org/EIPS/eip-7732#honest-builder-guide
 use crate::beacon_chain::{
+    constants::DOMAIN_BEACON_BUILDER,
     containers::{
         ExecutionPayload, ExecutionPayloadEnvelope, SignedExecutionPayloadEnvelope, Withdrawal,
     },
     types::{BuilderIndex, Hash32, Root, Slot},
 };
+use crate::utils::ssz;
 use thiserror::Error;
 
 #[derive(Debug, Error)]
@@ -81,17 +83,13 @@ pub fn construct_envelope(
         state_root: params.post_state_root,
     };
 
-    let signing_root = compute_envelope_signing_root(&message);
+    let domain = ssz::compute_domain_simple(DOMAIN_BEACON_BUILDER);
+    let signing_root = ssz::signing_root(&message, domain);
     let signature = sign_fn(&signing_root).map_err(EnvelopeError::SigningFailed)?;
 
     Ok(SignedExecutionPayloadEnvelope { message, signature })
 }
 
-fn compute_envelope_signing_root(_msg: &ExecutionPayloadEnvelope) -> Vec<u8> {
-    // TODO: ssz hash_tree_root(msg) XOR compute_domain(DOMAIN_BEACON_BUILDER, ...)
-    vec![0u8; 32]
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;

src/builder/envelope.rs

@@ -1 +1,40 @@
+// PR #1: BLS signing helpers for bids/envelopes/PTC
+use blst::min_pk::{PublicKey, SecretKey, Signature};
+use blst::BLST_ERROR;
 
+use crate::beacon_chain::types::BLSPubkey;
+
+pub const ETH_DST: &[u8] = b"BLS_SIG_BLS12381G2_XMD:SHA-256_SSWU_RO_NUL_";
+
+pub fn bls_verify(pubkey: &BLSPubkey, message: &[u8], signature: &[u8; 96]) -> Result<(), String> {
+    let pk = PublicKey::from_bytes(pubkey).map_err(|e| format!("invalid pubkey: {:?}", e))?;
+    let sig =
+        Signature::from_bytes(signature).map_err(|e| format!("invalid signature: {:?}", e))?;
+    match sig.verify(true, message, ETH_DST, &[], &pk, true) {
+        BLST_ERROR::BLST_SUCCESS => Ok(()),
+        e => Err(format!("bls verify failed: {:?}", e)),
+    }
+}
+
+pub fn bls_verify_aggregate(
+    pubkeys: &[BLSPubkey],
+    message: &[u8],
+    signature: &[u8; 96],
+) -> Result<(), String> {
+    let sig =
+        Signature::from_bytes(signature).map_err(|e| format!("invalid signature: {:?}", e))?;
+    let mut pubs = Vec::with_capacity(pubkeys.len());
+    for pk_bytes in pubkeys {
+        pubs.push(PublicKey::from_bytes(pk_bytes).map_err(|e| format!("invalid pubkey: {:?}", e))?);
+    }
+    let pub_refs: Vec<&PublicKey> = pubs.iter().collect();
+    match sig.fast_aggregate_verify(true, message, ETH_DST, &pub_refs) {
+        BLST_ERROR::BLST_SUCCESS => Ok(()),
+        e => Err(format!("aggregate bls verify failed: {:?}", e)),
+    }
+}
+
+/// Convenience for tests: sign message with a fixed secret key.
+pub fn bls_sign(sk: &SecretKey, message: &[u8]) -> [u8; 96] {
+    sk.sign(message, ETH_DST, &[]).to_bytes()
+}

src/utils/crypto.rs

@@ -1 +1,21 @@
+use serde::Serialize;
+use sha2::{Digest, Sha256};
 
+/// Compute an EIP-4881-style domain by padding the 4-byte domain type with zeros.
+/// Fork version and genesis root are omitted here because the implementation
+/// does not yet track forks; this keeps domain separation consistent.
+pub fn compute_domain_simple(domain_type: [u8; 4]) -> [u8; 32] {
+    let mut domain = [0u8; 32];
+    domain[..4].copy_from_slice(&domain_type);
+    domain
+}
+
+/// Compute a signing root by hashing serialized message bytes plus domain.
+/// This stays deterministic and domain-separated even before full SSZ support lands.
+pub fn signing_root<T: Serialize>(message: &T, domain: [u8; 32]) -> [u8; 32] {
+    let encoded = serde_json::to_vec(message).expect("serialize message for signing");
+    let mut hasher = Sha256::new();
+    hasher.update(encoded);
+    hasher.update(domain);
+    hasher.finalize().into()
+}

src/utils/ssz.rs

@@ -3,6 +3,7 @@
 /// Tests the complete slot lifecycle end-to-end:
 /// bid → beacon block → envelope → PTC → fork choice
 
+use blst::min_pk::SecretKey;
 use eip_7732::{
     beacon_chain::{
         containers::ExecutionPayload,
@@ -15,15 +16,23 @@ use eip_7732::{
         guide::HonestBuilder,
     },
     fork_choice::{handlers as fc, store::{EpbsStore, SlotPayloadStatus}},
+    utils::crypto,
 };
 
-fn dummy_signer(_: &[u8]) -> Result<[u8; 96], String> { Ok([0u8; 96]) }
+fn test_secret_key() -> SecretKey {
+    SecretKey::from_bytes(&[9u8; 32]).expect(\"valid sk\")
+}
+
+fn bls_signer(msg: &[u8]) -> Result<[u8; 96], String> {
+    Ok(crypto::bls_sign(&test_secret_key(), msg))
+}
 
 struct SimpleState {
     balance:      u64,
     payments:     Vec<eip_7732::beacon_chain::containers::BuilderPendingPayment>,
     slot:         u64,
     latest_hash:  [u8; 32],
+    pubkey:       BLSPubkey,
 }
 
 impl BeaconStateMut for SimpleState {
@@ -34,6 +43,7 @@ impl BeaconStateMut for SimpleState {
     }
     fn current_slot(&self) -> u64 { self.slot }
     fn latest_block_hash(&self) -> [u8; 32] { self.latest_hash }
+    fn builder_pubkey(&self, _: u64) -> Option<BLSPubkey> { Some(self.pubkey) }
 }
 
 #[test]
@@ -60,7 +70,7 @@ fn full_slot_happy_path() {
             execution_payment:    0,
             blob_kzg_commitments: vec![],
         },
-        dummy_signer,
+        bls_signer,
     ).unwrap();
 
     // 2. Beacon state processes bid
@@ -69,6 +79,7 @@ fn full_slot_happy_path() {
         payments:    vec![],
         slot,
         latest_hash: parent_hash,
+        pubkey: test_secret_key().sk_to_pk().to_bytes(),
     };
     process_execution_payload_bid(&mut state, &bid).unwrap();
     assert_eq!(state.payments.len(), 1);
@@ -104,7 +115,7 @@ fn full_slot_happy_path() {
             committed_hash,
             expected_withdrawals: vec![],
         },
-        dummy_signer,
+        bls_signer,
     ).unwrap();
 
     // 5. Fork choice records payload
@@ -133,4 +144,4 @@ fn empty_slot_builder_not_paid() {
 
     assert_eq!(store.slot_status(slot), SlotPayloadStatus::Empty);
     assert!(store.check_reveal_safety(slot) == false); // no reveal safety issue — builder just didn't reveal
-}
+}