iTextSharp.text.pdf.PdfStamper.CreateSignature C# (CSharp) Method

        public static PdfStamper CreateSignature(PdfReader reader, Stream os, char pdfVersion, string tempFile, bool append)
        {
            PdfStamper stp;
            if (tempFile == null) {
                ByteBuffer bout = new ByteBuffer();
                stp = new PdfStamper(reader, bout, pdfVersion, append);
                stp.sigApp = new PdfSignatureAppearance(stp.stamper);
                stp.sigApp.Sigout = bout;
            }
            else {
                if (Directory.Exists(tempFile))
                    tempFile = Path.GetTempFileName();
                FileStream fout = new FileStream(tempFile, FileMode.Create, FileAccess.Write);
                stp = new PdfStamper(reader, fout, pdfVersion, append);
                stp.sigApp = new PdfSignatureAppearance(stp.stamper);
                stp.sigApp.SetTempFile(tempFile);
            }
            stp.sigApp.Originalout = os;
            stp.sigApp.SetStamper(stp);
            stp.hasSignature = true;
            PdfDictionary catalog = reader.Catalog;
            PdfDictionary acroForm = (PdfDictionary)PdfReader.GetPdfObject(catalog.Get(PdfName.ACROFORM), catalog);
            if (acroForm != null) {
                acroForm.Remove(PdfName.NEEDAPPEARANCES);
                stp.stamper.MarkUsed(acroForm);
            }
            return stp;
        }