add epoch num to public randomness commit

proto/babylon/finality/v1/finality.proto

@@ -27,6 +27,8 @@ message PubRandCommit {
     // commitment is the value of the commitment
     // currently, it is the root of the merkle tree constructed by the public randomness
     bytes commitment = 3;
+    // epoch_num defines the epoch number that the commit falls into
+    uint64 epoch_num = 4;
 }
 
 // Evidence is the evidence that a finality provider has signed finality

proto/babylon/finality/v1/query.proto

@@ -102,6 +102,8 @@ message PubRandCommitResponse {
   uint64 num_pub_rand = 1;
   // commitment is the value of the commitment
   bytes commitment = 2;
+  // epoch_num defines the epoch number that the commit falls into
+  uint64 epoch_num = 3;
 }
 
 // QueryListPubRandCommitRequest is the request type for the

x/btcstaking/keeper/keeper.go

@@ -90,3 +90,12 @@ func (k Keeper) BeginBlocker(ctx context.Context) error {
 func (k Keeper) GetLastFinalizedEpoch(ctx context.Context) uint64 {
 	return k.ckptKeeper.GetLastFinalizedEpoch(ctx)
 }
+
+func (k Keeper) GetEpoch(ctx context.Context) uint64 {
+	epoch := k.ckptKeeper.GetEpoch(ctx)
+	if epoch == nil {
+		panic(fmt.Errorf("epoch cannot be nil"))
+	}
+
+	return epoch.EpochNumber
+}

x/btcstaking/types/errors.go

@@ -11,7 +11,6 @@ var (
 	ErrBTCDelegationNotFound        = errorsmod.Register(ModuleName, 1102, "the BTC delegation is not found")
 	ErrFpRegistered                 = errorsmod.Register(ModuleName, 1103, "the finality provider has already been registered")
 	ErrFpAlreadySlashed             = errorsmod.Register(ModuleName, 1104, "the finality provider has already been slashed")
-	ErrFpNotBTCTimestamped          = errorsmod.Register(ModuleName, 1105, "the finality provider is not BTC timestamped yet")
 	ErrBTCStakingNotActivated       = errorsmod.Register(ModuleName, 1106, "the BTC staking protocol is not activated yet")
 	ErrBTCHeightNotFound            = errorsmod.Register(ModuleName, 1107, "the BTC height is not found")
 	ErrReusedStakingTx              = errorsmod.Register(ModuleName, 1108, "the BTC staking tx is already used")

x/finality/keeper/msg_server.go

@@ -7,12 +7,13 @@ import (
 	"time"
 
 	errorsmod "cosmossdk.io/errors"
-	bbn "github.com/babylonlabs-io/babylon/types"
-	bstypes "github.com/babylonlabs-io/babylon/x/btcstaking/types"
-	"github.com/babylonlabs-io/babylon/x/finality/types"
 	"github.com/cosmos/cosmos-sdk/telemetry"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	govtypes "github.com/cosmos/cosmos-sdk/x/gov/types"
+
+	bbn "github.com/babylonlabs-io/babylon/types"
+	bstypes "github.com/babylonlabs-io/babylon/x/btcstaking/types"
+	"github.com/babylonlabs-io/babylon/x/finality/types"
 )
 
 type msgServer struct {
@@ -82,7 +83,7 @@ func (ms msgServer) AddFinalitySig(goCtx context.Context, req *types.MsgAddFinal
 	}
 	fpPK := req.FpBtcPk
 	if ms.BTCStakingKeeper.GetVotingPower(ctx, fpPK.MustMarshal(), req.BlockHeight) == 0 {
-		return nil, types.ErrInvalidFinalitySig.Wrapf("the finality provider %v does not have voting power at height %d", fpPK.MustMarshal(), req.BlockHeight)
+		return nil, types.ErrInvalidFinalitySig.Wrapf("the finality provider %s does not have voting power at height %d", fpPK.MarshalHex(), req.BlockHeight)
 	}
 
 	// ensure the finality provider has not cast the same vote yet
@@ -101,6 +102,13 @@ func (ms msgServer) AddFinalitySig(goCtx context.Context, req *types.MsgAddFinal
 	if err != nil {
 		return nil, err
 	}
+	// ensure the finality provider's last randomness commit is already finalised by BTC timestamping
+	finalizedEpoch := ms.BTCStakingKeeper.GetLastFinalizedEpoch(ctx)
+	if finalizedEpoch < prCommit.EpochNum {
+		return nil, types.ErrPubRandCommitNotBTCTimestamped.
+			Wrapf("the finality provider %s last committed epoch number: %d, last finalized epoch number: %d",
+				fp.BtcPk.MarshalHex(), prCommit.EpochNum, finalizedEpoch)
+	}
 
 	// verify the finality signature message w.r.t. the public randomness commitment
 	// including the public randomness inclusion proof and the finality signature
@@ -132,7 +140,7 @@ func (ms msgServer) AddFinalitySig(goCtx context.Context, req *types.MsgAddFinal
 		// if this finality provider has also signed canonical block, slash it
 		canonicalSig, err := ms.GetSig(ctx, req.BlockHeight, fpPK)
 		if err == nil {
-			//set canonial sig
+			// set canonial sig
 			evidence.CanonicalFinalitySig = canonicalSig
 			// slash this finality provider, including setting its voting power to
 			// zero, extracting its BTC SK, and emit an event
@@ -206,6 +214,7 @@ func (ms msgServer) CommitPubRandList(goCtx context.Context, req *types.MsgCommi
 		StartHeight: req.StartHeight,
 		NumPubRand:  req.NumPubRand,
 		Commitment:  req.Commitment,
+		EpochNum:    ms.BTCStakingKeeper.GetEpoch(ctx),
 	}
 
 	// get last public randomness commitment

x/finality/types/errors.go

@@ -6,15 +6,16 @@ import (
 
 // x/finality module sentinel errors
 var (
-	ErrBlockNotFound         = errorsmod.Register(ModuleName, 1100, "Block is not found")
-	ErrVoteNotFound          = errorsmod.Register(ModuleName, 1101, "vote is not found")
-	ErrHeightTooHigh         = errorsmod.Register(ModuleName, 1102, "the chain has not reached the given height yet")
-	ErrPubRandNotFound       = errorsmod.Register(ModuleName, 1103, "public randomness is not found")
-	ErrPubRandCommitNotFound = errorsmod.Register(ModuleName, 1104, "public randomness commitment is not found")
-	ErrNoPubRandYet          = errorsmod.Register(ModuleName, 1105, "the finality provider has not committed any public randomness yet")
-	ErrTooFewPubRand         = errorsmod.Register(ModuleName, 1106, "the request contains too few public randomness")
-	ErrInvalidPubRand        = errorsmod.Register(ModuleName, 1107, "the public randomness list is invalid")
-	ErrEvidenceNotFound      = errorsmod.Register(ModuleName, 1108, "evidence is not found")
-	ErrInvalidFinalitySig    = errorsmod.Register(ModuleName, 1109, "finality signature is not valid")
-	ErrNoSlashableEvidence   = errorsmod.Register(ModuleName, 1110, "there is no slashable evidence")
+	ErrBlockNotFound                  = errorsmod.Register(ModuleName, 1100, "Block is not found")
+	ErrVoteNotFound                   = errorsmod.Register(ModuleName, 1101, "vote is not found")
+	ErrHeightTooHigh                  = errorsmod.Register(ModuleName, 1102, "the chain has not reached the given height yet")
+	ErrPubRandNotFound                = errorsmod.Register(ModuleName, 1103, "public randomness is not found")
+	ErrPubRandCommitNotFound          = errorsmod.Register(ModuleName, 1104, "public randomness commitment is not found")
+	ErrNoPubRandYet                   = errorsmod.Register(ModuleName, 1105, "the finality provider has not committed any public randomness yet")
+	ErrTooFewPubRand                  = errorsmod.Register(ModuleName, 1106, "the request contains too few public randomness")
+	ErrInvalidPubRand                 = errorsmod.Register(ModuleName, 1107, "the public randomness list is invalid")
+	ErrEvidenceNotFound               = errorsmod.Register(ModuleName, 1108, "evidence is not found")
+	ErrInvalidFinalitySig             = errorsmod.Register(ModuleName, 1109, "finality signature is not valid")
+	ErrNoSlashableEvidence            = errorsmod.Register(ModuleName, 1110, "there is no slashable evidence")
+	ErrPubRandCommitNotBTCTimestamped = errorsmod.Register(ModuleName, 1111, "the public randomness commit is not BTC timestamped yet")
 )

x/finality/types/expected_keepers.go

@@ -17,6 +17,7 @@ type BTCStakingKeeper interface {
 	GetBTCStakingActivatedHeight(ctx context.Context) (uint64, error)
 	GetVotingPowerDistCache(ctx context.Context, height uint64) (*bstypes.VotingPowerDistCache, error)
 	RemoveVotingPowerDistCache(ctx context.Context, height uint64)
+	GetEpoch(ctx context.Context) uint64
 	GetLastFinalizedEpoch(ctx context.Context) uint64
 	RevertSluggishFinalityProvider(ctx context.Context, fpBTCPK []byte) error
 }