/// <summary>
/// Realiza la contrafirma de una firma CAdES existente
/// </summary>
/// <param name="sigDocument"></param>
/// <param name="signerInfoNode"></param>
/// <param name="parameters"></param>
/// <returns></returns>
public SignatureDocument CounterSign(SignatureDocument sigDocument, SignerInfoNode signerInfoNode, SignatureParameters parameters)
{
if (sigDocument == null)
{
throw new Exception("Se necesita una firma previa para poder realizar la cofirma");
}
if (signerInfoNode == null)
{
throw new Exception("Se necesita especificar el nodo de firma para aplicar la contrafirma");
}
CheckParameters(parameters);
byte[] signature = null;
using (MemoryStream ms = new MemoryStream(signerInfoNode.SignerInformation.GetSignature()))
{
byte[] toBeSigned = ToBeSigned(new CmsProcessableInputStream(ms), parameters, null, true);
signature = parameters.Signer.SignData(toBeSigned, parameters.DigestMethod);
}
CustomCMSSignedDataGenerator generator = CreateSignedGenerator(new PreComputedSigner(signature), parameters, null);
var result = generator.GenerateCounterSigners(signerInfoNode.SignerInformation);
SignerInformation updatedSI = SignerInformation.AddCounterSigners(signerInfoNode.SignerInformation, result);
List <X509Certificate> certs = new List <X509Certificate>();
IX509Store originalCertStore = sigDocument.SignedData.GetCertificates("Collection");
signerInfoNode.SignerInformation = updatedSI;
CollectionUtilities.AddRange(certs, GetCertificatesFromStore(originalCertStore));
X509CertificateParser parser = new X509CertificateParser();
var signerCertificate = parser.ReadCertificate(parameters.Certificate.GetRawCertData());
if (!CheckCertExists(signerCertificate, originalCertStore))
{
certs.Add(signerCertificate);
}
IX509Store certStore = X509StoreFactory.Create("Certificate/Collection", new X509CollectionStoreParameters(certs));
CmsSignedData newSignedData = CmsSignedData.ReplaceCertificatesAndCrls(sigDocument.SignedData, certStore, sigDocument.SignedData.GetCrls("Collection"), null);
return(new SignatureDocument(newSignedData));
}