x509 sha256的XML签名失败

Question

我希望“xml签名与x509 sha256”但这个代码只给签名（byte []）ı想签名xmldocument用这个x509请帮帮我

XmlDocument docc = new XmlDocument();
docc.Load("C:\\Users\\bera\\Desktop\\Sertifika\\aa.xml");

X509Store storeMyCurrentUser = new X509Store(StoreName.My, StoreLocation.CurrentUser);
storeMyCurrentUser.Open(OpenFlags.MaxAllowed);

X509Certificate2 certRCA = new X509Certificate2("C:\\Users\\bera\\Desktop\\RCA.p12", "0123456789");
if (!storeMyCurrentUser.Certificates.Contains(certRCA))
     storeMyCurrentUser.Add(certRCA);
 RSACryptoServiceProvider _provider = null;
 //doc.OuterXml
 byte[] data = Encoding.Default.GetBytes(doc.OuterXml);
 if (certRCA.HasPrivateKey)
 {
     _provider = (RSACryptoServiceProvider)certRCA.PrivateKey;
     byte[] sigedBytes = _provider.SignData(data, "SHA256");
     string a= System.Text.Encoding.ASCII.GetString(sigedBytes);
     Console.WriteLine(a);