Decrypt xml file passing the certificate password

I need to decrypt an XML file, but I've already passed the certificate password. I can do similar actions, like signing the file without the certificate driver asking for the password. Following:

SecureString senha = new SecureString();
foreach(char c in senhaCert.ToCharArray())
senha.AppendChar(c);

RSACryptoServiceProvider rsaKeyBase = new RSACryptoServiceProvider();
try {
    rsaKeyBase = (RSACryptoServiceProvider) cert.PrivateKey;
} catch (Exception) {
    return "E_acessar_chave_certificado";
}

CspParameters cspParams = new CspParameters();
cspParams.ProviderName = rsaKeyBase.CspKeyContainerInfo.ProviderName;
cspParams.ProviderType = rsaKeyBase.CspKeyContainerInfo.ProviderType;
cspParams.KeyNumber = rsaKeyBase.CspKeyContainerInfo.KeyNumber == KeyNumber.Exchange ? 1 : 2;
cspParams.KeyContainerName = rsaKeyBase.CspKeyContainerInfo.KeyContainerName;
cspParams.KeyPassword = senha;
cspParams.Flags = CspProviderFlags.NoPrompt | CspProviderFlags.UseDefaultKeyContainer;

// Instancia a nova chave de assinatura RSA e salva no contêiner. 
try {
    rsaKey = new RSACryptoServiceProvider(cspParams);
} catch (Exception) {
    return "E_SenhaCert_Incorreta";
}
try {
    rsaKey = (RSACryptoServiceProvider) cert.PrivateKey;
} catch (Exception) {
    return "E_acessar_chave_certificado";
}

// Criando um documento Xml.
XmlDocument xmlDoc = new XmlDocument();

// Carregando um arquivo Xml dentro do objeto XmlDocument.
xmlDoc.PreserveWhitespace = true;
xmlDoc.Load(fileName);

// Check arguments. 
if (xmlDoc == null) return "E_nao_carregou_xml";
if (rsaKey == null) return "E_key_invalida";

// Instancia o SignedXml.
SignedXml signedXml = new SignedXml(xmlDoc);

// Adiciona a chave RSA no documento SignedXml.
signedXml.SigningKey = rsaKey;

// Cria a referencia que deve ser assinada.
Reference reference = new Reference();
reference.Uri = "";

// Adiciona uma transformação envolvida com a referência.
XmlDsigEnvelopedSignatureTransform env = new XmlDsigEnvelopedSignatureTransform();
reference.AddTransform(env);

// Adiciona a referencia no objeto SignedXml.
signedXml.AddReference(reference);

// Instancia o KeyInfo.
KeyInfo keyInfo = new KeyInfo();

// Carrega o certificado dentro do objeto KeyInfoX509Data
// e adiciona no objeto KeyInfo.
keyInfo.AddClause(new KeyInfoX509Data(cert));

signedXml.KeyInfo = keyInfo;

// Grava a assinatura.
signedXml.ComputeSignature();

// Pega a representação do XML da assinatura e salva 
// no objeto XmlElement.
XmlElement xmlDigitalSignature = signedXml.GetXml();

// Anexa o elemento no documento XML.
xmlDoc.DocumentElement.AppendChild(xmlDoc.ImportNode(xmlDigitalSignature, true));

// Salvo o documento.
// Salvo o documento XML.
try {
    xmlDoc.Save(fileName);
} catch {
    return "E_salvar_xml";
}

To decrypt I use the following commands:

// Instancia a class XmlDocument
XmlDocument xmlDoc = new XmlDocument();

// Carrega o arquivo XML dentro do objeto XmlDocument.
xmlDoc.PreserveWhitespace = true;
try {
    xmlDoc.Load(fileName);
} catch (Exception) {
    return "E_nao_carregou_xml";
}

// Descriptografa o documento.
if (xmlDoc == null) return "E_xml_invalido";

// Instancia a class EncryptedXml.
EncryptedXml exml = new EncryptedXml(xmlDoc);

try {
    exml.DecryptDocument();
} catch (Exception) {
    return "E_DecryptDocument";
}

try {
    xmlDoc.Save(Path.GetDirectoryName(fileName) + "\" + Path.GetFileNameWithoutExtension(fileName) + "_decrypted.xml");
} catch {
    return "E_salvar_xml";
}

I wanted to decrypt without the driver's driver requesting the password.