chore: Java interop PR

common/common_test.go

@@ -0,0 +1,46 @@
+package common_test
+
+import (
+	"bytes"
+	"encoding/hex"
+	"testing"
+
+	"github.com/crate-crypto/go-ipa/common"
+)
+
+func TestJavaRegressionOneEndian(t *testing.T) {
+	hexStr := "f6e31f7a565a390b48fdd24569ac10d43562d19de37ea951c7f9f250a339d059"
+	byteArray := hexStrToBytes(hexStr)
+	_scalar, err := common.ReadScalar(bytes.NewReader(byteArray))
+
+	if err == nil {
+		t.Fatalf("expected an error because the scalar is too large")
+	}
+	_ = _scalar
+}
+func TestJavaRegressionOtherEndian(t *testing.T) {
+	hexStr := "f6e31f7a565a390b48fdd24569ac10d43562d19de37ea951c7f9f250a339d059"
+	byteArray := hexStrToBytes(hexStr)
+	reverse(byteArray)
+	_scalar, err := common.ReadScalar(bytes.NewReader(byteArray))
+	if err == nil {
+		t.Fatalf("expected an error because the scalar is too large, even though we changed the endian")
+	}
+	_ = _scalar
+}
+
+func reverse(data []byte) {
+	for i, j := 0, len(data)-1; i < j; i, j = i+1, j-1 {
+		data[i], data[j] = data[j], data[i]
+	}
+}
+
+func hexStrToBytes(numStr string) []byte {
+
+	// Use Hex package
+	byteArray, err := hex.DecodeString(numStr)
+	if err != nil {
+		panic(err)
+	}
+	return byteArray
+}