using System;
using System.Collections;
using System.IO;
using System.Security.Cryptography;
using System.Security.Cryptography.Pkcs;
using iTextSharp.text;
using iTextSharp.text.pdf;
using Org.BouncyCastle.X509;
using SysX509 = System.Security.Cryptography.X509Certificates;
/// <summary>
/// Helper para el firmado de PDFs con la librería iTextSharp
/// </summary>
public static class PDF
{
/// Firma un documento
public static void SignHashed(string Source, string Target, SysX509.X509Certificate2 Certificate, string Reason, string Location, bool AddVisibleSign)
{ X509CertificateParser objCP = new X509CertificateParser();
X509Certificate[] objChain = new X509Certificate[] { objCP.ReadCertificate(Certificate.RawData) };
PdfReader objReader = new PdfReader(Source);
PdfStamper objStamper = PdfStamper.CreateSignature(objReader, new FileStream(Target, FileMode.Create), '\0');
PdfSignatureAppearance objSA = objStamper.SignatureAppearance;
if (AddVisibleSign)
objSA.SetVisibleSignature(new Rectangle(100, 100, 300, 200), 1, null);
objSA.SignDate = DateTime.Now;
objSA.SetCrypto(null, objChain, null, null);
objSA.Reason = Reason;
objSA.Location = Location;
objSA.Acro6Layers = true;
objSA.Render = PdfSignatureAppearance.SignatureRender.NameAndDescription;
PdfSignature objSignature = new PdfSignature(PdfName.ADOBE_PPKMS, PdfName.ADBE_PKCS7_SHA1);
objSignature.Date = new PdfDate(objSA.SignDate);
objSignature.Name = PdfPKCS7.GetSubjectFields(objChain[0]).GetField("CN");
if (objSA.Reason != null)
objSignature.Reason = objSA.Reason;
if (objSA.Location != null)
objSignature.Location = objSA.Location;
objSA.CryptoDictionary = objSignature;
int intCSize = 4000;
Hashtable objTable = new Hashtable();
objTable[PdfName.CONTENTS] = intCSize * 2 + 2;
objSA.PreClose(objTable);
HashAlgorithm objSHA1 = new SHA1CryptoServiceProvider();
Stream objStream = objSA.RangeStream;
int intRead = 0;
byte[] bytBuffer = new byte[8192];
while ((intRead = objStream.Read(bytBuffer, 0, 8192)) > 0)
objSHA1.TransformBlock(bytBuffer, 0, intRead, bytBuffer, 0);
objSHA1.TransformFinalBlock(bytBuffer, 0, 0);
byte[] bytPK = SignMsg(objSHA1.Hash, Certificate, false);
byte[] bytOut = new byte[intCSize];
PdfDictionary objDict = new PdfDictionary();
Array.Copy(bytPK, 0, bytOut, 0, bytPK.Length);
objDict.Put(PdfName.CONTENTS, new PdfString(bytOut).SetHexWriting(true));
objSA.Close(objDict);
}
/// Crea la firma CMS/PKCS #7
private static byte[] SignMsg(byte[] Message, SysX509.X509Certificate2 SignerCertificate, bool Detached)
{ //Creamos el contenedor
ContentInfo contentInfo = new ContentInfo(Message);
//Instanciamos el objeto SignedCms con el contenedor
SignedCms objSignedCms = new SignedCms(contentInfo, Detached);
//Creamos el "firmante"
CmsSigner objCmsSigner = new CmsSigner(SignerCertificate);
// Include the following line if the top certificate in the
// smartcard is not in the trusted list.
objCmsSigner.IncludeOption = SysX509.X509IncludeOption.EndCertOnly;
// Sign the CMS/PKCS #7 message. The second argument is
// needed to ask for the pin.
objSignedCms.ComputeSignature(objCmsSigner, false);
//Encodeamos el mensaje CMS/PKCS #7
return objSignedCms.Encode();
}
}
