stupidgcm: add stupidXchacha20poly1305

Implementation copied from
https://github.com/golang/crypto/blob/32db794688a5a24a23a43f2a984cecd5b3d8da58/chacha20poly1305/xchacha20poly1305.go

1 files changed, 20 insertions, 0 deletions

diff --git a/internal/stupidgcm/stupidxchacha_test.go b/internal/stupidgcm/stupidxchacha_test.go
new file mode 100644
index 0000000..fdea8b5
--- /dev/null
+++ b/internal/stupidgcm/stupidxchacha_test.go
@@ -0,0 +1,20 @@
+// +build !without_openssl
+
+package stupidgcm
+
+import (
+	"testing"
+
+	"golang.org/x/crypto/chacha20poly1305"
+)
+
+func TestStupidXchacha20poly1305(t *testing.T) {
+	key := randBytes(32)
+	c := NewXchacha20poly1305(key)
+	ref, err := chacha20poly1305.NewX(key)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	testCiphers(t, c, ref)
+}