feat(adr-035): eots manager signing requests (#184)

extends eots manager to store signing requests


[Addreses](https://github.com/babylonlabs-io/pm/blob/main/adr/adr-035-slashing-protection.md#eots-manager-protection)

CHANGELOG.md

@@ -42,6 +42,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 * [#175](https://github.com/babylonlabs-io/finality-provider/pull/175) adds: `eotsd version` command
 * [#179](https://github.com/babylonlabs-io/finality-provider/pull/179) Change `btc_pk` text to `eots_pk` in CLI
 * [#182](https://github.com/babylonlabs-io/finality-provider/pull/182) Remove fp manager
+* [#184](https://github.com/babylonlabs-io/finality-provider/pull/184) eots manager sign record store
 
 ### Bug Fixes
 

eotsmanager/localmanager.go

@@ -1,13 +1,13 @@
 package eotsmanager
 
 import (
+	"bytes"
 	"encoding/hex"
 	"fmt"
+	"github.com/babylonlabs-io/finality-provider/metrics"
 	"strings"
 	"sync"
 
-	"github.com/babylonlabs-io/finality-provider/metrics"
-
 	"github.com/babylonlabs-io/babylon/crypto/eots"
 	bbntypes "github.com/babylonlabs-io/babylon/types"
 	"github.com/btcsuite/btcd/btcec/v2"
@@ -194,6 +194,20 @@ func (lm *LocalEOTSManager) CreateRandomnessPairList(fpPk []byte, chainID []byte
 }
 
 func (lm *LocalEOTSManager) SignEOTS(fpPk []byte, chainID []byte, msg []byte, height uint64, passphrase string) (*btcec.ModNScalar, error) {
+	record, found, err := lm.es.GetSignRecord(height)
+	if err != nil {
+		return nil, fmt.Errorf("error getting sign record: %w", err)
+	} else if found {
+		if bytes.Equal(msg, record.BlockHash) {
+			var s btcec.ModNScalar
+			s.SetByteSlice(record.Signature)
+
+			return &s, nil
+		}
+
+		return nil, eotstypes.ErrDoubleSign
+	}
+
 	privRand, _, err := lm.getRandomnessPair(fpPk, chainID, height, passphrase)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get private randomness: %w", err)
@@ -208,7 +222,17 @@ func (lm *LocalEOTSManager) SignEOTS(fpPk []byte, chainID []byte, msg []byte, he
 	lm.metrics.IncrementEotsFpTotalEotsSignCounter(hex.EncodeToString(fpPk))
 	lm.metrics.SetEotsFpLastEotsSignHeight(hex.EncodeToString(fpPk), float64(height))
 
-	return eots.Sign(privKey, privRand, msg)
+	signedBytes, err := eots.Sign(privKey, privRand, msg)
+	if err != nil {
+		return nil, err
+	}
+
+	b := signedBytes.Bytes()
+	if err := lm.es.SaveSignRecord(height, msg, fpPk, b[:]); err != nil {
+		return nil, fmt.Errorf("failed to save signing record: %w", err)
+	}
+
+	return signedBytes, nil
 }
 
 func (lm *LocalEOTSManager) SignSchnorrSig(fpPk []byte, msg []byte, passphrase string) (*schnorr.Signature, error) {

eotsmanager/localmanager_test.go

@@ -92,3 +92,48 @@ func FuzzCreateRandomnessPairList(f *testing.F) {
 		}
 	})
 }
+
+func FuzzSignRecord(f *testing.F) {
+	testutil.AddRandomSeedsToFuzzer(f, 10)
+	f.Fuzz(func(t *testing.T, seed int64) {
+		r := rand.New(rand.NewSource(seed))
+
+		fpName := testutil.GenRandomHexStr(r, 4)
+		homeDir := filepath.Join(t.TempDir(), "eots-home")
+		eotsCfg := eotscfg.DefaultConfigWithHomePath(homeDir)
+		dbBackend, err := eotsCfg.DatabaseConfig.GetDBBackend()
+		defer func() {
+			dbBackend.Close()
+			err := os.RemoveAll(homeDir)
+			require.NoError(t, err)
+		}()
+		require.NoError(t, err)
+		lm, err := eotsmanager.NewLocalEOTSManager(homeDir, eotsCfg.KeyringBackend, dbBackend, zap.NewNop())
+		require.NoError(t, err)
+
+		fpPk, err := lm.CreateKey(fpName, passphrase, hdPath)
+		require.NoError(t, err)
+
+		chainID := datagen.GenRandomByteArray(r, 10)
+		startHeight := datagen.RandomInt(r, 100)
+		num := r.Intn(10) + 1
+		pubRandList, err := lm.CreateRandomnessPairList(fpPk, chainID, startHeight, uint32(num), passphrase)
+		require.NoError(t, err)
+		require.Len(t, pubRandList, num)
+
+		msg := datagen.GenRandomByteArray(r, 32)
+
+		sig, err := lm.SignEOTS(fpPk, chainID, msg, startHeight, passphrase)
+		require.NoError(t, err)
+		require.NotNil(t, sig)
+
+		// we expect return from db
+		sig2, err := lm.SignEOTS(fpPk, chainID, msg, startHeight, passphrase)
+		require.NoError(t, err)
+		require.Equal(t, sig, sig2)
+
+		// same height diff msg
+		_, err = lm.SignEOTS(fpPk, chainID, datagen.GenRandomByteArray(r, 32), startHeight, passphrase)
+		require.ErrorIs(t, err, types.ErrDoubleSign)
+	})
+}

eotsmanager/proto/signstore.proto

@@ -0,0 +1,13 @@
+syntax = "proto3";
+
+package proto;
+
+option go_package = "github.com/babylonlabs-io/finality-provider/eotsmanager/proto";
+
+// SigningRecord represents a record of a signing operation.
+message SigningRecord {
+  bytes block_hash = 1;     // The hash of the block.
+  bytes public_key = 2;     // The public key used for signing.
+  bytes signature = 3;      // The signature of the block.
+  int64 timestamp = 4;      // The timestamp of the signing operation, in Unix seconds.
+}