crypto: ed25519 & sr25519 batch verification (#6120)

Co-authored-by: Aleksandr Bezobchuk <alexanderbez@users.noreply.github.com>
Co-authored-by: Anton Kaliaev <anton.kalyaev@gmail.com>

crypto/batch/batch.go

@@ -0,0 +1,22 @@
+package batch
+
+import (
+	"github.com/tendermint/tendermint/crypto"
+	"github.com/tendermint/tendermint/crypto/ed25519"
+	"github.com/tendermint/tendermint/crypto/sr25519"
+)
+
+// CreateBatchVerifier checks if a key type implements the batch verifier interface.
+// Currently only ed25519 & sr25519 supports batch verification.
+func CreateBatchVerifier(pk crypto.PubKey) (crypto.BatchVerifier, bool) {
+
+	switch pk.Type() {
+	case ed25519.KeyType:
+		return ed25519.NewBatchVerifier(), true
+	case sr25519.KeyType:
+		return sr25519.NewBatchVerifier(), true
+	}
+
+	// case where the key does not support batch verification
+	return nil, false
+}