public void Sign(string SigReason, string SigContact, string SigLocation, bool visible)
        {
            PdfReader reader = new PdfReader(this.inputPDF);
/*ERROR-->*/PdfEncryptor.Encrypt(reader, new FileStream(this.outputPDF, FileMode.Create, FileAccess.Write), true, null, null, PdfWriter.AllowFillIn | PdfWriter.AllowScreenReaders);
            PdfStamper st = PdfStamper.CreateSignature(reader, new FileStream(this.outputPDF, FileMode.Create, FileAccess.Write), '', null, true);
            st.MoreInfo = this.metadata.getMetaData();
            st.XmpMetadata = this.metadata.getStreamedMetaData();
            PdfSignatureAppearance sap = st.SignatureAppearance;

            sap.SetCrypto(this.myCert.Akp, this.myCert.Chain, null, PdfSignatureAppearance.WINCER_SIGNED);
            sap.Reason = SigReason;
            sap.Contact = SigContact;
            sap.Location = SigLocation;

            if (visible)
                sap.SetVisibleSignature(new iTextSharp.text.Rectangle(100, 100, 250, 150), 1, null);

            st.Close();

        }