feat(prover): add flag for guardian prover

cmd/flags/prover.go

@@ -183,6 +183,13 @@ var (
 		Usage:    "HTTP endpoint for main guardian prover health check server",
 		Category: proverCategory,
 	}
+	// Guardian prover specific flag
+	EnableLivenessBondProof = &cli.BoolFlag{
+		Name:     "prover.enableLivenessBondProof",
+		Usage:    "Toggles whether the proof is a dummy proof or returns keccak256(RETURN_LIVENESS_BOND) as proof",
+		Value:    false,
+		Category: proverCategory,
+	}
 )
 
 // ProverFlags All prover flags.

prover/config.go

@@ -37,6 +37,7 @@ type Config struct {
 	BackOffRetryInterval                    time.Duration
 	ProveUnassignedBlocks                   bool
 	ContesterMode                           bool
+	EnableLivenessBondProof                 bool
 	RPCTimeout                              time.Duration
 	WaitReceiptTimeout                      time.Duration
 	ProveBlockGasLimit                      *uint64
@@ -146,6 +147,7 @@ func NewConfigFromCliContext(c *cli.Context) (*Config, error) {
 		BackOffRetryInterval:                    c.Duration(flags.BackOffRetryInterval.Name),
 		ProveUnassignedBlocks:                   c.Bool(flags.ProveUnassignedBlocks.Name),
 		ContesterMode:                           c.Bool(flags.ContesterMode.Name),
+		EnableLivenessBondProof:                 c.Bool(flags.EnableLivenessBondProof.Name),
 		RPCTimeout:                              c.Duration(flags.RPCTimeout.Name),
 		WaitReceiptTimeout:                      c.Duration(flags.WaitReceiptTimeout.Name),
 		ProveBlockGasLimit:                      proveBlockTxGasLimit,

prover/proof_producer/guardian_producer.go

@@ -5,17 +5,20 @@ import (
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/log"
 
 	"github.com/taikoxyz/taiko-client/bindings"
 	"github.com/taikoxyz/taiko-client/bindings/encoding"
 )
 
 // GuardianProofProducer always returns an optimistic (dummy) proof.
-type GuardianProofProducer struct{ *DummyProofProducer }
+type GuardianProofProducer struct {
+	LivenessBond bool
+	*DummyProofProducer
+}
 
 // RequestProof implements the ProofProducer interface.
-// TODO: support returning `keccak256("RETURN_LIVENESS_BOND")` as proof.
 func (g *GuardianProofProducer) RequestProof(
 	ctx context.Context,
 	opts *ProofRequestOptions,
@@ -31,6 +34,18 @@ func (g *GuardianProofProducer) RequestProof(
 		"hash", header.Hash(),
 	)
 
+	if g.LivenessBond {
+		return &ProofWithHeader{
+			BlockID: blockID,
+			Meta:    meta,
+			Header:  header,
+			Proof:   crypto.Keccak256([]byte("RETURN_LIVENESS_BOND")),
+			Degree:  CircuitsIdx,
+			Opts:    opts,
+			Tier:    g.Tier(),
+		}, nil
+	}
+
 	return g.DummyProofProducer.RequestProof(ctx, opts, blockID, meta, header, g.Tier())
 }
 

prover/proof_producer/guardian_producer_test.go

@@ -7,6 +7,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/stretchr/testify/require"
 
 	"github.com/taikoxyz/taiko-client/bindings"
@@ -49,3 +50,41 @@ func TestGuardianProducerRequestProof(t *testing.T) {
 	require.Equal(t, res.Tier, encoding.TierGuardianID)
 	require.NotEmpty(t, res.Proof)
 }
+
+func TestGuardianProducerRequestProofReturnLivenessBond(t *testing.T) {
+	header := &types.Header{
+		ParentHash:  randHash(),
+		UncleHash:   randHash(),
+		Coinbase:    common.BytesToAddress(randHash().Bytes()),
+		Root:        randHash(),
+		TxHash:      randHash(),
+		ReceiptHash: randHash(),
+		Difficulty:  common.Big0,
+		Number:      common.Big256,
+		GasLimit:    1024,
+		GasUsed:     1024,
+		Time:        uint64(time.Now().Unix()),
+		Extra:       randHash().Bytes(),
+		MixDigest:   randHash(),
+		Nonce:       types.BlockNonce{},
+	}
+
+	var (
+		producer = &GuardianProofProducer{LivenessBond: true}
+		blockID  = common.Big32
+	)
+	res, err := producer.RequestProof(
+		context.Background(),
+		&ProofRequestOptions{},
+		blockID,
+		&bindings.TaikoDataBlockMetadata{},
+		header,
+	)
+	require.Nil(t, err)
+
+	require.Equal(t, res.BlockID, blockID)
+	require.Equal(t, res.Header, header)
+	require.Equal(t, res.Tier, encoding.TierGuardianID)
+	require.NotEmpty(t, res.Proof)
+	require.Equal(t, res.Proof, crypto.Keccak256([]byte("RETURN_LIVENESS_BOND")))
+}

prover/prover.go

@@ -218,7 +218,10 @@ func InitFromConfig(ctx context.Context, p *Prover, cfg *Config) (err error) {
 			}
 			producer = zkEvmRpcdProducer
 		case encoding.TierGuardianID:
-			producer = &proofProducer.GuardianProofProducer{DummyProofProducer: new(proofProducer.DummyProofProducer)}
+			producer = &proofProducer.GuardianProofProducer{
+				LivenessBond:       p.cfg.EnableLivenessBondProof,
+				DummyProofProducer: new(proofProducer.DummyProofProducer),
+			}
 		}
 
 		if submitter, err = proofSubmitter.New(