Do not use go-ethereum for hasher.

go.mod

@@ -62,6 +62,7 @@ require (
 	github.com/lib/pq v1.10.9
 	github.com/redis/go-redis/v9 v9.0.4
 	github.com/testcontainers/testcontainers-go/modules/postgres v0.39.0
+	golang.org/x/crypto v0.41.0
 )
 
 require (
@@ -308,7 +309,6 @@ require (
 	go.uber.org/multierr v1.11.0 // indirect
 	go.uber.org/ratelimit v0.3.1 // indirect
 	golang.org/x/arch v0.8.0 // indirect
-	golang.org/x/crypto v0.41.0 // indirect
 	golang.org/x/net v0.43.0 // indirect
 	golang.org/x/sys v0.36.0 // indirect
 	golang.org/x/term v0.34.0 // indirect

protocol/hashing.go

@@ -1,11 +1,30 @@
 package protocol
 
-import "github.com/ethereum/go-ethereum/crypto"
+import (
+	"hash"
+	"sync"
+
+	"golang.org/x/crypto/sha3"
+)
+
+var hasherPool = sync.Pool{
+	New: func() any {
+		return sha3.NewLegacyKeccak256()
+	},
+}
 
 // Keccak256 computes the Keccak256 hash of the input.
 func Keccak256(data []byte) [32]byte {
-	hash := crypto.Keccak256(data)
-	var result [32]byte
-	copy(result[:], hash)
-	return result
+	h, ok := hasherPool.Get().(hash.Hash)
+	if !ok {
+		// This should never happen, but just in case.
+		h = sha3.NewLegacyKeccak256()
+	}
+
+	h.Reset()
+	h.Write(data) //nolint // keccak256 never returns an error
+	var out [32]byte
+	copy(out[:], h.Sum(nil))
+	hasherPool.Put(h)
+	return out
 }

protocol/hashing_test.go

@@ -0,0 +1,25 @@
+package protocol
+
+import (
+	"testing"
+
+	"golang.org/x/crypto/sha3"
+)
+
+var data = []byte("The quick brown fox jumps over the lazy dogThe quick brown fox jumps over the lazy dogThe quick brown fox jumps over the lazy dogThe quick brown fox jumps over the lazy dogThe quick brown fox jumps over the lazy dogThe quick brown fox jumps over the lazy dog")
+
+func BenchmarkHashing(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		Keccak256(data)
+	}
+}
+
+func BenchmarkHashinbBaseline(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		h := sha3.NewLegacyKeccak256()
+		h.Write(data)
+		var out [32]byte
+		copy(out[:], h.Sum(nil))
+		hasherPool.Put(h)
+	}
+}