public static X509Certificate2Collection SelecionarCertificado(string serial)
    {
        X509Store store = new X509Store(StoreName.My, StoreLocation.CurrentUser);
        var Key = new RSACryptoServiceProvider();
        store.Open(OpenFlags.ReadOnly | OpenFlags.OpenExistingOnly);
        X509Certificate2Collection collection = store.Certificates;
        X509Certificate2Collection fcollection = collection.Find(X509FindType.FindBySerialNumber, serial, true);

        return fcollection;
    }

    public static RSACryptoServiceProvider LerDispositivo(RSACryptoServiceProvider key, string PIN)
    {
        CspParameters csp = new CspParameters(key.CspKeyContainerInfo.ProviderType, key.CspKeyContainerInfo.ProviderName);
        SecureString ss = new SecureString();
        foreach (char a in PIN)
        {
            ss.AppendChar(a);
        }
        csp.ProviderName = key.CspKeyContainerInfo.ProviderName;
        csp.ProviderType = key.CspKeyContainerInfo.ProviderType;
        csp.KeyNumber = key.CspKeyContainerInfo.KeyNumber == KeyNumber.Exchange ? 1 : 2;
        csp.KeyContainerName = key.CspKeyContainerInfo.KeyContainerName;
        csp.KeyPassword = ss;
        csp.Flags = CspProviderFlags.NoPrompt | CspProviderFlags.UseDefaultKeyContainer;

        RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(csp);
        return rsa;
    }

X509Certificate2Collection collection = Certificados.SelecionarCertificado(serial);

        if (collection.Count == 1)
        {
            X509Certificate2 x509Cert = collection[0];

            StreamReader SR = null;

            try
            {
                SR = System.IO.File.OpenText(arquivo);
                string xmlString = SR.ReadToEnd();
                SR.Close();
                SR = null;

                XmlDocument doc = new XmlDocument();

                doc.PreserveWhitespace = false;

                doc.LoadXml(xmlString);

                if (doc.GetElementsByTagName(tagAssinatura).Count == 0)
                {
                    resultado.Result = false;
                    resultado.Mensagem = $"A tag de assinatura {tagAssinatura.Trim()} não existe no XML. (Código do Erro: 5)";

                    Console.WriteLine(resultado.Mensagem);

                    return resultado;
                    //throw new Exception($"A tag de assinatura {tagAssinatura.Trim()} não existe no XML. (Código do Erro: 5)");
                }
                else if (doc.GetElementsByTagName(tagAtributoId).Count == 0)
                {
                    resultado.Result = false;
                    resultado.Mensagem = $"A tag de assinatura {tagAtributoId.Trim()} não existe no XML. (Código do Erro: 4)";

                    Console.WriteLine(resultado.Mensagem);

                    return resultado;
                    //throw new Exception($"A tag de assinatura {tagAtributoId.Trim()} não existe no XML. (Código do Erro: 4)");
                }
                else
                {
                    XmlDocument XMLDoc;

                    XmlNodeList lists = doc.GetElementsByTagName(tagAssinatura);
                    foreach (XmlNode nodes in lists)
                    {
                        foreach (XmlNode childNodes in nodes.ChildNodes)
                        {
                            if (!childNodes.Name.Equals(tagAtributoId))
                                continue;

                            if (childNodes.NextSibling != null && childNodes.NextSibling.Name.Equals("Signature"))
                                continue;

                            Reference reference = new Reference("");
                            reference.Uri = "";

                            XmlElement childElemen = (XmlElement)childNodes;
                            if (childElemen.GetAttributeNode("Id") != null)
                            {
                                reference.Uri = "#" + "RPS" + numeroRPS.ToString().PadLeft(15, '0');
                            }
                            else if (childElemen.GetAttributeNode("id") != null)
                            {
                                reference.Uri = "#" + childElemen.GetAttributeNode("id").Value;
                            }

                            SignedXml signedXml = new SignedXml(doc);


                            KeyInfo keyInfo = new KeyInfo();

                            signedXml.KeyInfo = keyInfo;
                            //signedXml.SigningKey = x509Cert.PrivateKey;
                            RSACryptoServiceProvider Key = new RSACryptoServiceProvider();
                            Key = (System.Security.Cryptography.RSACryptoServiceProvider)x509Cert.PrivateKey;
                            signedXml.SigningKey = x509Cert.PrivateKey;
                            signedXml.SigningKey = Certificados.LerDispositivo(Key, PIN);
                            signedXml.SignedInfo.SignatureMethod = SignedXml.XmlDsigRSASHA1Url;
                            reference.DigestMethod = SignedXml.XmlDsigSHA1Url;


                            XmlDsigEnvelopedSignatureTransform env = new XmlDsigEnvelopedSignatureTransform();
                            reference.AddTransform(env);
                            XmlDsigC14NTransform c14 = new XmlDsigC14NTransform();
                            reference.AddTransform(c14);

                            signedXml.AddReference(reference);

                            keyInfo.AddClause(new KeyInfoX509Data(x509Cert));

                            signedXml.KeyInfo = keyInfo;
                            signedXml.ComputeSignature();

                            XmlElement xmlDigitalSignature = signedXml.GetXml();

                            nodes.AppendChild(doc.ImportNode(xmlDigitalSignature, true));

                        }
                    }

                    XMLDoc = new XmlDocument();
                    XMLDoc.PreserveWhitespace = false;
                    XMLDoc = doc;
                    string conteudoXMLAssinado = XMLDoc.OuterXml;
                    using (StreamWriter sw = System.IO.File.CreateText(arquivo))
                    {
                        sw.Write(conteudoXMLAssinado);
                        sw.Flush();
                        sw.Close();
                    }

                    resultado.Result = true;
                    resultado.Mensagem = $"Procecesso de assinatura efetuado com sucesso!!!";

                    Console.WriteLine(resultado.Mensagem);

                    return resultado;
                }

var assinarL = await client.AssinarXmlAsync(empresa.Caminho + "\NFSe-LOTE" + model.IdLote.ToString().PadLeft(15, '0') + ".xml", "EnviarLoteRpsSincronoEnvio", "LoteRps", empresa.Serial, model.IdLote.ToString(), empresa.Pin);