public bool Sign(string iSignReason, string iSignContact, string iSignLocation, bool visible, string iImageString) { string vCertificatesPath = "CN=" + CertificatesName; #region Geting Certs X509Store store = new X509Store(_storedName, _storedLocation); StorePermission sp = new StorePermission(PermissionState.Unrestricted); sp.Flags = StorePermissionFlags.OpenStore; sp.Assert(); store.Open(OpenFlags.MaxAllowed); X509Certificate2 cert = null; int i = 0; while ((i < store.Certificates.Count) && (cert == null)) { if (store.Certificates[i].Subject.ToUpper().Contains(vCertificatesPath)) { cert = store.Certificates[i]; } else { i++; } } store.Close(); if (cert == null) { throw new CryptographicException("Certificate is NULL. Certificate can not be found"); } Org.BouncyCastle.X509.X509CertificateParser cp = new Org.BouncyCastle.X509.X509CertificateParser(); var cerRawData = cert.RawData; var certificates = cp.ReadCertificate(cerRawData); Org.BouncyCastle.X509.X509Certificate[] chain = new Org.BouncyCastle.X509.X509Certificate[] { certificates }; var chainFirst = GetChainBouncyCastle(cert); #endregion Geting Certs PdfReader reader = null; if (string.IsNullOrEmpty(inputPdfFileString)) { reader = new PdfReader(inputPdfStream); } else { reader = new PdfReader(this.inputPdfFileString); } if (outputPdfStream == null && string.IsNullOrEmpty(outputPdfFileString) == false) { outputPdfStream = new FileStream(this.outputPdfFileString, FileMode.OpenOrCreate, FileAccess.Write); } if (reader != null && outputPdfStream != null) { #region Standard Signing PdfStamper vStamper = PdfStamper.CreateSignature(reader, outputPdfStream, '\0', null, false); vStamper.MoreInfo = this.settingMetadata.GetMetaDataHashtable(); vStamper.XmpMetadata = this.settingMetadata.GetStreamedMetaData(); PdfSignatureAppearance vSignatureAppearance = vStamper.SignatureAppearance; vSignatureAppearance.SetCrypto(null, chain, null, PdfSignatureAppearance.SELF_SIGNED); vSignatureAppearance.SignDate = SignDate; vSignatureAppearance.Reason = iSignReason; vSignatureAppearance.Contact = iSignContact; vSignatureAppearance.Location = iSignLocation; vSignatureAppearance.Acro6Layers = true; vSignatureAppearance.Render = PdfSignatureAppearance.SignatureRender.Description; if (visible) { vSignatureAppearance.SetVisibleSignature( new iTextSharp.text.Rectangle(ImageLocation.Width, ImageLocation.Height, ImageLocation.Width + ImageSize.Width, ImageLocation.Height + ImageSize.Height), 1, null); if (File.Exists(iImageString)) { iTextSharp.text.Image vImage = iTextSharp.text.Image.GetInstance(iImageString); vSignatureAppearance.Image = vImage; } } vSignatureAppearance.SetExternalDigest(new byte[128], new byte[20], "RSA"); #endregion Standard Signing #region Self Signed Mode PdfSignature dic = new PdfSignature(PdfName.ADOBE_PPKMS, PdfName.ADBE_PKCS7_SHA1); dic.Date = new PdfDate(vSignatureAppearance.SignDate); var vName = PdfPKCS7.GetSubjectFields(chain[0]).GetField("CN"); dic.Name = vName; if (vSignatureAppearance.Reason != null) { dic.Reason = vSignatureAppearance.Reason; } if (vSignatureAppearance.Location != null) { dic.Location = vSignatureAppearance.Location; } vSignatureAppearance.CryptoDictionary = dic; int csize = 4000; Dictionary <PdfName, int> exc = new Dictionary <PdfName, int>(); exc[PdfName.CONTENTS] = csize * 2 + 2; vSignatureAppearance.PreClose(new Hashtable(exc)); HashAlgorithm sha = new SHA1CryptoServiceProvider(); Stream s = vSignatureAppearance.RangeStream; int read = 0; byte[] buff = new byte[8192]; while ((read = s.Read(buff, 0, 8192)) > 0) { sha.TransformBlock(buff, 0, read, buff, 0); } sha.TransformFinalBlock(buff, 0, 0); byte[] pk = SignMsg(sha.Hash, cert, false); byte[] outc = new byte[csize]; PdfDictionary dic2 = new PdfDictionary(); Array.Copy(pk, 0, outc, 0, pk.Length); dic2.Put(PdfName.CONTENTS, new PdfString(outc).SetHexWriting(true)); vSignatureAppearance.Close(dic2); #endregion Self Signed Mode if (vSignatureAppearance.IsPreClosed() == false) { vStamper.Close(); } reader.Close(); return(true); } return(false); }