public ActionResult Index(SignatureStartModel model)
        {
            byte[]             toSignBytes, transferData;
            SignatureAlgorithm signatureAlg;

            try {
                // Verify if the userfile exists and get its absolute path.
                string userfilePath;
                if (!StorageMock.TryGetFile(model.UserFile, out userfilePath))
                {
                    return(HttpNotFound());
                }

                // Decode the user's certificate.
                var cert = PKCertificate.Decode(model.CertContent);

                // Get an instance of the PadesSigner class.
                var padesSigner = new PadesSigner();

                // Set the file to be signed.
                padesSigner.SetPdfToSign(userfilePath);

                // Set the signer certificate.
                padesSigner.SetSigningCertificate(cert);

                // Set the signature policy.
                padesSigner.SetPolicy(GetSignaturePolicy());

                // Set a visual representation for the signature.
                padesSigner.SetVisualRepresentation(PadesVisualElements.GetVisualRepresentationForPkiSdk(cert));

                // Generate the "to-sign-bytes". This method also yields the signature algorithm that must
                // be used on the client-side, based on the signature policy, as well as the "transfer data",
                // a byte-array that will be needed on the next step.
                toSignBytes = padesSigner.GetToSignBytes(out signatureAlg, out transferData);
            } catch (ValidationException ex) {
                // Some of the operations above may throw a ValidationException, for instance if the certificate
                // encoding cannot be read or if the certificate is expired.
                ModelState.AddModelError("", ex.ValidationResults.ToString());
                return(View());
            }

            // On the next step (Complete action), we'll need once again some information:
            // - The thumbprint of the selected certificate.
            // - The "transfer data" used to validate the signature in complete action. Its content is stored in
            //   a temporary file (with extension .bin) to be shared with the Complete action.
            // - The "to-sign-hash" (digest of the "to-sign-bytes") to be signed. (see signature-complete-form.js)
            // - The OID of the digest algorithm to be used during the signature operation.
            // We'll store these values on TempData, which is a dictionary shared between actions.
            TempData["SignatureCompleteModel"] = new SignatureCompleteModel()
            {
                CertThumb          = model.CertThumb,
                TransferDataFileId = StorageMock.Store(transferData, ".bin"),
                ToSignHash         = signatureAlg.DigestAlgorithm.ComputeHash(toSignBytes),
                DigestAlgorithmOid = signatureAlg.DigestAlgorithm.Oid
            };

            return(RedirectToAction("Complete", new { userfile = model.UserFile }));
        }
        public IHttpActionResult Start(SignatureStartRequest request)
        {
            byte[]             toSignBytes, transferData;
            SignatureAlgorithm signatureAlg;

            try {
                // Decode the user's certificate
                var cert = PKCertificate.Decode(request.Certificate);

                // Instantiate a PadesSigner class
                var padesSigner = new PadesSigner();

                // Set the PDF to sign, which in the case of this example is a fixed sample document
                if (!string.IsNullOrEmpty(request.FileId))
                {
                    padesSigner.SetPdfToSign(Storage.GetFile(request.FileId));
                }
                else
                {
                    padesSigner.SetPdfToSign(Storage.GetSampleDocContent());
                }

                // Set the signer certificate
                padesSigner.SetSigningCertificate(cert);

                // Set the signature policy
                padesSigner.SetPolicy(getSignaturePolicy());

                // Set the signature's visual representation options (optional)
                padesSigner.SetVisualRepresentation(getVisualRepresentation(cert));

                // Generate the "to-sign-bytes". This method also yields the signature algorithm that must
                // be used on the client-side, based on the signature policy, as well as the "transfer data",
                // a byte-array that will be needed on the next step.
                toSignBytes = padesSigner.GetToSignBytes(out signatureAlg, out transferData);
            } catch (ValidationException ex) {
                // Some of the operations above may throw a ValidationException, for instance if the certificate
                // encoding cannot be read or if the certificate is expired.
                return(new ResponseMessageResult(Request.CreateResponse(HttpStatusCode.BadRequest, new ValidationErrorModel(ex.ValidationResults))));
            }

            // Create response with some informations that we'll use on Complete action and on client-side.
            var response = new SignatureStartResponse()
            {
                // The "transfer data" for PDF signatures can be as large as the original PDF itself. Therefore, we mustn't use a hidden field
                // on the page to store it. Here we're using our storage mock (see file Classes\Storage.cs) to simulate storing the transfer data
                // on a database and saving on a hidden field on the page only the ID that can be used later to retrieve it. Another option would
                // be to store the transfer data on the Session dictionary.
                TransferDataFileId = Storage.StoreFile(transferData),

                // Send to the javascript the "to sign hash" of the document (digest of the "to-sign-bytes") and the digest algorithm that must
                // be used on the signature algorithm computation
                ToSignBytes        = toSignBytes,
                DigestAlgorithmOid = signatureAlg.DigestAlgorithm.Oid
            };

            return(Ok(response));
        }
Пример #3
0
        protected void SubmitCertificateButton_Click(object sender, EventArgs e)
        {
            byte[]             toSignBytes, transferData;
            SignatureAlgorithm signatureAlg;

            try {
                // Decode the user's certificate.
                var cert = PKCertificate.Decode(Convert.FromBase64String(CertificateField.Value));

                // Instantiate a PadesSigner class.
                var padesSigner = new PadesSigner();

                // Set the PDF to sign, which in the case of this example is a fixed sample document.
                padesSigner.SetPdfToSign(Storage.GetSampleDocContent());

                // Set the signer certificate.
                padesSigner.SetSigningCertificate(cert);

                // Set the signature policy.
                padesSigner.SetPolicy(getSignaturePolicy());

                // Set the signature's visual representation options (optional).
                padesSigner.SetVisualRepresentation(getVisualRepresentation(cert));

                // Generate the "to-sign-bytes". This method also yields the signature algorithm that must
                // be used on the client-side, based on the signature policy, as well as the "transfer data",
                // a byte-array that will be needed on the next step.
                toSignBytes = padesSigner.GetToSignBytes(out signatureAlg, out transferData);
            }
            catch (ValidationException ex) {
                // Some of the operations above may throw a ValidationException, for instance if the certificate
                // encoding cannot be read or if the certificate is expired.
                ex.ValidationResults.Errors.ForEach(ve => ModelState.AddModelError("", ve.ToString()));
                return;
            }

            // The "transfer data" for PDF signatures can be as large as the original PDF itself. Therefore, we
            // mustn't use a hidden field on the page to store it. Here we're using our storage mock
            // (see file Classes\Storage.cs) to simulate storing the transfer data on a database and saving on a
            // hidden field on the page only the ID that can be used later to retrieve it. Another option would
            // be to store the transfer data on the Session dictionary.
            TransferDataFileIdField.Value = Storage.StoreFile(transferData);

            // Send to the javascript the "to sign hash" of the document (digest of the "to-sign-bytes") and the
            // digest algorithm that must be used on the signature algorithm computation.
            ToSignHashField.Value      = Convert.ToBase64String(signatureAlg.DigestAlgorithm.ComputeHash(toSignBytes));
            DigestAlgorithmField.Value = signatureAlg.DigestAlgorithm.Oid;
        }
        public ActionResult Start(BatchSignatureStartRequest request)
        {
            byte[]             toSignBytes, transferData;
            SignatureAlgorithm signatureAlg;

            try {
                // Decode the user's certificate
                var cert = PKCertificate.Decode(request.CertContent);

                // Instantiate a PadesSigner class
                var padesSigner = new PadesSigner();

                // Set the PDF to sign, which in the case of this example is one of the batch documents
                padesSigner.SetPdfToSign(StorageMock.GetBatchDocPath(request.Id));

                // Set the signer certificate
                padesSigner.SetSigningCertificate(cert);

                // Set the signature policy.
                padesSigner.SetPolicy(GetSignaturePolicy());

                // Set a visual representation for the signature.
                padesSigner.SetVisualRepresentation(PadesVisualElements.GetVisualRepresentationForPkiSdk(cert));

                // Generate the "to-sign-bytes". This method also yields the signature algorithm that must
                // be used on the client-side, based on the signature policy, as well as the "transfer data",
                // a byte-array that will be needed on the next step.
                toSignBytes = padesSigner.GetToSignBytes(out signatureAlg, out transferData);
            } catch (ValidationException ex) {
                // Some of the operations above may throw a ValidationException, for instance if the certificate
                // encoding cannot be read or if the certificate is expired.
                return(new HttpStatusCodeResult(500, ex.ValidationResults.ToString()));
            }

            // For the next steps, we'll need once again some information:
            // - The "transfer data" filename. Its content is stored in a temporary file (with extension .bin) to
            // be shared with the Complete action.
            // - The "to-sign-hash" (digest of the "to-sign-bytes"). And the OID of the digest algorithm to be
            // used during the signature operation. this information is need in the signature computation with
            // Web PKI component. (see batch-signature-form.js)
            return(Json(new BatchSignatureStartResponse()
            {
                TransferDataFileId = StorageMock.Store(transferData, ".bin"),
                ToSignHash = signatureAlg.DigestAlgorithm.ComputeHash(toSignBytes),
                DigestAlgorithmOid = signatureAlg.DigestAlgorithm.Oid
            }));
        }
        public ActionResult Start(SignatureStartModel model)
        {
            byte[]             toSignBytes, transferData;
            SignatureAlgorithm signatureAlg;

            try {
                // Verify if the userfile exists and get its absolute path.
                string userfilePath;
                if (!StorageMock.TryGetFile(model.UserFile, out userfilePath))
                {
                    return(HttpNotFound());
                }

                // Decode the user's certificate.
                var cert = PKCertificate.Decode(model.CertContent);

                // Get an instance of the PadesSigner class.
                var padesSigner = new PadesSigner();

                // Set the file to be signed.
                padesSigner.SetPdfToSign(userfilePath);

                // REQUIRED!
                // Provide the signer's certificate. You must sign with a valid digital
                // certificate of a doctor, who was registered on CRM. In this sample,
                // we used a sample certificate stored on server to do the execute this
                // sample.
                padesSigner.SetSigningCertificate(cert);

                // REQUIRED!
                // Define the trust arbitrator, which will configure the signer to
                // some kind of certificate. In the case of this sample, only
                // ICP-Brasil certificates will be accepted in the defined standard.
                var trustArbitrator = new LinkedTrustArbitrator(TrustArbitrators.PkiBrazil);
#if DEBUG
                // For development purposes, we also trust in Lacuna Software's test certificates.
                var lacunaRoot = Lacuna.Pki.PKCertificate.Decode(Convert.FromBase64String("MIIGGTCCBAGgAwIBAgIBATANBgkqhkiG9w0BAQ0FADBfMQswCQYDVQQGEwJCUjETMBEGA1UECgwKSUNQLUJyYXNpbDEdMBsGA1UECwwUTGFjdW5hIFNvZnR3YXJlIC0gTFMxHDAaBgNVBAMME0xhY3VuYSBSb290IFRlc3QgdjEwHhcNMTUwMTE2MTk1MjQ1WhcNMjUwMTE2MTk1MTU1WjBfMQswCQYDVQQGEwJCUjETMBEGA1UECgwKSUNQLUJyYXNpbDEdMBsGA1UECwwUTGFjdW5hIFNvZnR3YXJlIC0gTFMxHDAaBgNVBAMME0xhY3VuYSBSb290IFRlc3QgdjEwggIiMA0GCSqGSIb3DQEBAQUAA4ICDwAwggIKAoICAQCDm5ey0c4ij8xnDnV2EBATjJbZjteEh8BBiGtVx4dWpXbWQ6hEw8E28UyLsF6lCM2YjQge329g7hMANnrnrNCvH1ny4VbhHMe4eStiik/GMTzC79PYS6BNfsMsS6+W18a45eyi/2qTIHhJYN8xS4/7pAjrVpjL9dubALdiwr26I3a4S/h9vD2iKJ1giWnHU74ckVp6BiRXrz2ox5Ps7p420VbVU6dTy7QR2mrhAus5va9VeY1LjvCH9S9uSf6kt+HP1Kj7hlOOlcnluXmuD/IN68/CQeC+dLOr0xKmDvYv7GWluXhxpUZmh6NaLzSGzGNACobOezKmby06s4CvsmMKQuZrTx113+vJkYSgI2mBN5v8LH60DzuvIhMvDLWPZCwfnyGCNHBwBbdgzBWjsfuSFJyaKdJLmpu5OdWNOLjvexqEC9VG83biYr+8XMiWl8gUW8SFqEpNoLJ59nwsRf/R5R96XTnG3mdVugcyjR9xe/og1IgJFf9Op/cBgCjNR/UAr+nizHO3Q9LECnu1pbTtGZguGDMABc+/CwKyxirwlRpiu9DkdBlNRgdd5IgDkcgFkTjmA41ytU0LOIbxpKHn9/gZCevq/8CyMa61kgjzg1067BTslex2xUZm44oVGrEdx5kg/Hz1Xydg4DHa4qlG61XsTDJhM84EvnJr3ZTYOwIDAQABo4HfMIHcMDwGA1UdIAQ1MDMwMQYFYEwBAQAwKDAmBggrBgEFBQcCARYaaHR0cDovL2xhY3VuYXNvZnR3YXJlLmNvbS8wOwYDVR0fBDQwMjAwoC6gLIYqaHR0cDovL2NhdGVzdC5sYWN1bmFzb2Z0d2FyZS5jb20vY3Jscy9yb290MB8GA1UdIwQYMBaAFPtdXjCI7ZOfGUg8mrCoEw9z9zywMB0GA1UdDgQWBBT7XV4wiO2TnxlIPJqwqBMPc/c8sDAPBgNVHRMBAf8EBTADAQH/MA4GA1UdDwEB/wQEAwIBBjANBgkqhkiG9w0BAQ0FAAOCAgEAN/b8hNGhBrWiuE67A8kmom1iRUl4b8FAA8PUmEocbFv/BjLpp2EPoZ0C+I1xWT5ijr4qcujIMsjOCosmv0M6bzYvn+3TnbzoZ3tb0aYUiX4ZtjoaTYR1fXFhC7LJTkCN2phYdh4rvMlLXGcBI7zA5+Ispm5CwohcGT3QVWun2zbrXFCIigRrd3qxRbKLxIZYS0KW4X2tetRMpX6DPr3MiuT3VSO3WIRG+o5Rg09L9QNXYQ74l2+1augJJpjGYEWPKzHVKVJtf1fj87HN/3pZ5Hr2oqDvVUIUGFRj7BSel9BgcgVaWqmgTMSEvQWmjq0KJpeqWbYcXXw8lunuJoENEItv+Iykv3NsDfNXgS+8dXSzTiV1ZfCdfAjbalzcxGn522pcCceTyc/iiUT72I3+3BfRKaMGMURu8lbUMxd/38Xfut3Kv5sLFG0JclqD1rhI15W4hmvb5bvol+a/WAYT277jwdBO8BVSnJ2vvBUzH9KAw6pAJJBCGw/1dZkegLMFibXdEzjAW4z7wyx2c5+cmXzE/2SFV2cO3mJAtpaO99uwLvj3Y3quMBuIhDGD0ReDXNAniXXXVPfE96NUcDF2Dq2g8kj+EmxPy6PGZ15p1XZO1yiqsGEVreIXqgcU1tPUv8peNYb6jHTHuUyXGTzbsamGZFEDsLG7NRxg0eZWP1w="));
                trustArbitrator.Add(new TrustedRoots(lacunaRoot));
#endif
                // REQUIRED!
                // Use a policy accepted by ICP-Brasil. We use the trust arbitrator
                // defined above to configure the policy.
                padesSigner.SetPolicy(PadesPoliciesForGeneration.GetPadesBasic(trustArbitrator));

                // REQUIRED!
                // Use a custom signature field name. This field MUST have the
                // "Emitente" keyword as the last keyword.
                padesSigner.SetCustomSignatureFieldName("Signature1 Emitente");

                // REQUIRED!
                // Set Certification Level to not allow changes after signed.
                padesSigner.SetCertificationLevel(PadesCertificationLevel.CertifiedNoChangesAllowed);

                // Set a visual representation for the signature.
                padesSigner.SetVisualRepresentation(PadesVisualElements.GetVisualRepresentationForPkiSdk(cert));

                // Generate the "to-sign-bytes". This method also yields the signature algorithm that must
                // be used on the client-side, based on the signature policy, as well as the "transfer data",
                // a byte-array that will be needed on the next step.
                toSignBytes = padesSigner.GetToSignBytes(out signatureAlg, out transferData);
            } catch (ValidationException ex) {
                // Some of the operations above may throw a ValidationException, for instance if the certificate
                // encoding cannot be read or if the certificate is expired.
                ModelState.AddModelError("", ex.ValidationResults.ToString());
                return(View());
            }

            // On the next step (Complete action), we'll need once again some information:
            // - The thumbprint of the selected certificate.
            // - The "transfer data" used to validate the signature in complete action. Its content is stored in
            //   a temporary file (with extension .bin) to be shared with the Complete action.
            // - The "to-sign-hash" (digest of the "to-sign-bytes") to be signed. (see signature-complete-form.js)
            // - The OID of the digest algorithm to be used during the signature operation.
            // We'll store these values on TempData, which is a dictionary shared between actions.
            TempData["SignatureCompleteModel"] = new SignatureCompleteModel()
            {
                CertThumb          = model.CertThumb,
                TransferDataFileId = StorageMock.Store(transferData, ".bin"),
                ToSignHash         = signatureAlg.DigestAlgorithm.ComputeHash(toSignBytes),
                DigestAlgorithmOid = signatureAlg.DigestAlgorithm.Oid
            };

            return(RedirectToAction("Complete", new { userfile = model.UserFile }));
        }
Пример #6
0
        public IHttpActionResult Start(BatchSignatureStartRequest request)
        {
            byte[]             toSignBytes, transferData;
            SignatureAlgorithm signatureAlg;

            try {
                // Decode the user's certificate
                var cert = PKCertificate.Decode(request.CertContent);

                // Instantiate a PadesSigner class
                var padesSigner = new PadesSigner();

                // Set the PDF to sign, which in the case of this example is one of the batch documents
                padesSigner.SetPdfToSign(Storage.GetBatchDocContent(request.Id));

                // Set the signer certificate
                padesSigner.SetSigningCertificate(cert);

                // Set the signature policy
                padesSigner.SetPolicy(getSignaturePolicy());

                // Set the signature's visual representation options (this is optional). For more information, see
                // http://pki.lacunasoftware.com/Help/html/98095ec7-2742-4d1f-9709-681c684eb13b.htm
                var visual = new PadesVisualRepresentation2()
                {
                    // Text of the visual representation
                    Text = new PadesVisualText()
                    {
                        // Compose the message
                        CustomText = $"Assinado digitalmente por {cert.SubjectDisplayName}",

                        // Specify that the signing time should also be rendered
                        IncludeSigningTime = true,

                        // Optionally set the horizontal alignment of the text ('Left' or 'Right'), if not set the default is Left
                        HorizontalAlign = PadesTextHorizontalAlign.Left
                    },
                    // Background image of the visual representation
                    Image = new PadesVisualImage()
                    {
                        // We'll use as background the image in Content/PdfStamp.png
                        Content = Storage.GetPdfStampContent(),

                        // Opacity is an integer from 0 to 100 (0 is completely transparent, 100 is completely opaque).
                        Opacity = 50,

                        // Align the image to the right
                        HorizontalAlign = PadesHorizontalAlign.Right
                    },
                    // Set the position of the visual representation
                    Position = PadesVisualAutoPositioning.GetFootnote()
                };
                padesSigner.SetVisualRepresentation(visual);

                // Generate the "to-sign-bytes". This method also yields the signature algorithm that must
                // be used on the client-side, based on the signature policy, as well as the "transfer data",
                // a byte-array that will be needed on the next step.
                toSignBytes = padesSigner.GetToSignBytes(out signatureAlg, out transferData);
            } catch (ValidationException ex) {
                // Some of the operations above may throw a ValidationException, for instance if the certificate
                // encoding cannot be read or if the certificate is expired.
                var message = Request.CreateErrorResponse(HttpStatusCode.InternalServerError, ex.ValidationResults.ToString());
                return(ResponseMessage(message));
            }

            // For the next steps, we'll need once again some information:
            // - The "transfer data" filename. Its content is stored in a temporary file (with extension .bin) to
            // be shared with the Complete action.
            // - The "to-sign-hash" (digest of the "to-sign-bytes"). And the OID of the digest algorithm to be
            // used during the signature operation. this information is need in the signature computation with
            // Web PKI component. (see batch-signature-form.js)
            return(Ok(new BatchSignatureStartResponse()
            {
                TransferDataFileId = Storage.StoreFile(transferData, ".bin"),
                ToSignHash = signatureAlg.DigestAlgorithm.ComputeHash(toSignBytes),
                DigestAlgorithmOid = signatureAlg.DigestAlgorithm.Oid
            }));
        }
        public ActionResult Index(SignatureStartModel model)
        {
            byte[]             toSignBytes, transferData;
            SignatureAlgorithm signatureAlg;

            try {
                // Decode the user's certificate
                var cert = PKCertificate.Decode(model.CertContent);

                // Instantiate a PadesSigner class
                var padesSigner = new PadesSigner();

                // Set the PDF to sign, which in the case of this example is a fixed sample document
                padesSigner.SetPdfToSign(Storage.GetSampleDocContent());

                // Set the signer certificate
                padesSigner.SetSigningCertificate(cert);

                // Set the signature policy
                padesSigner.SetPolicy(getSignaturePolicy());

                // Set the signature's visual representation options (this is optional). For more information, see
                // http://pki.lacunasoftware.com/Help/html/98095ec7-2742-4d1f-9709-681c684eb13b.htm
                var visual = new PadesVisualRepresentation2()
                {
                    // Text of the visual representation
                    Text = new PadesVisualText()
                    {
                        // Compose the message
                        CustomText = String.Format("Assinado digitalmente por {0}", cert.SubjectDisplayName),

                        // Specify that the signing time should also be rendered
                        IncludeSigningTime = true,

                        // Optionally set the horizontal alignment of the text ('Left' or 'Right'), if not set the default is Left
                        HorizontalAlign = PadesTextHorizontalAlign.Left
                    },
                    // Background image of the visual representation
                    Image = new PadesVisualImage()
                    {
                        // We'll use as background the image in Content/PdfStamp.png
                        Content = Storage.GetPdfStampContent(),

                        // Opacity is an integer from 0 to 100 (0 is completely transparent, 100 is completely opaque).
                        Opacity = 50,

                        // Align the image to the right
                        HorizontalAlign = PadesHorizontalAlign.Right
                    },
                    // Set the position of the visual representation
                    Position = PadesVisualAutoPositioning.GetFootnote()
                };
                padesSigner.SetVisualRepresentation(visual);

                // Generate the "to-sign-bytes". This method also yields the signature algorithm that must
                // be used on the client-side, based on the signature policy, as well as the "transfer data",
                // a byte-array that will be needed on the next step.
                toSignBytes = padesSigner.GetToSignBytes(out signatureAlg, out transferData);
            } catch (ValidationException ex) {
                // Some of the operations above may throw a ValidationException, for instance if the certificate
                // encoding cannot be read or if the certificate is expired.
                ModelState.AddModelError("", ex.ValidationResults.ToString());
                return(View());
            }

            // On the next step (Complete action), we'll need once again some information:
            // - The content of the selected certificate only used to render the user's certificate information
            //  after the signature is completed. It is no longer needed for the signature process.
            // - The thumbprint of the selected certificate.
            // - The "transfer data" used to validate the signature in complete action.
            // - The "to-sign-hash" (digest of the "to-sign-bytes") to be signed. (see signature-complete-form.js)
            // - The OID of the digest algorithm to be used during the signature operation.
            // We'll store these values on TempData, which is a dictionary shared between actions.
            TempData["SignatureCompleteModel"] = new SignatureCompleteModel()
            {
                CertContent        = model.CertContent,
                CertThumb          = model.CertThumb,
                TransferData       = transferData,
                ToSignHash         = signatureAlg.DigestAlgorithm.ComputeHash(toSignBytes),
                DigestAlgorithmOid = signatureAlg.DigestAlgorithm.Oid
            };

            return(RedirectToAction("Complete"));
        }
        private void startNextSignature()
        {
            // Increment the index of the document currently being signed.
            DocumentIndex += 1;

            // Check if we have reached the end of the batch, in which case we fill the hidden field
            // "ToSignHashField" with value "(end)", which signals to the javascript on batch-signature-form.js
            // that the process is completed and the page can be unblocked.
            if (DocumentIndex == DocumentIds.Count)
            {
                ToSignHashField.Value = "(end)";
                return;
            }

            // Get the ID of the document currently being signed.
            var docId = DocumentIds[DocumentIndex];

            byte[]             toSignBytes, transferData;
            SignatureAlgorithm signatureAlg;

            try {
                // Decode the user's certificate.
                var cert = PKCertificate.Decode(Convert.FromBase64String(CertificateField.Value));

                // Instantiate a PadesSigner class.
                var padesSigner = new PadesSigner();

                // Set the PDF to sign.
                padesSigner.SetPdfToSign(Storage.GetBatchDocContent(docId));

                // Set the signer certificate.
                padesSigner.SetSigningCertificate(cert);

                // Set the signature policy.
                padesSigner.SetPolicy(getSignaturePolicy());

                // Set the signature's visual representation options (optional).
                padesSigner.SetVisualRepresentation(getVisualRepresentation(cert));

                // Generate the "to-sign-bytes". This method also yields the signature algorithm that must
                // be used on the client-side, based on the signature policy, as well as the "transfer data",
                // a byte-array that will be needed on the next step.
                toSignBytes = padesSigner.GetToSignBytes(out signatureAlg, out transferData);
            }
            catch (ValidationException ex) {
                // One or more validations failed. We log the error, update the page with a summary of what
                // happened to this document and start the next signature.
                logger.Error(ex, "Validation error starting the signature of a batch document");
                setValidationError(ex.ValidationResults);
                startNextSignature();
                return;
            }
            catch (Exception ex) {
                // An error has occurred. We log the error, update the page with a summary of what happened to
                // this document and start the next signature.
                logger.Error(ex, "Error starting the signature of a batch document");
                setError(ex.Message);
                startNextSignature();
                return;
            }

            // The "transfer data" for PDF signatures can be as large as the original PDF itself. Therefore, we
            // mustn't use a hidden field on the page to store it. Here we're using our storage mock
            // (see file Classes\Storage.cs) to simulate storing the transfer data on a database and saving on a
            // hidden field on the page only the ID that can be used later to retrieve it. Another option would
            // be to store the transfer data on the Session dictionary.
            TransferDataFileIdField.Value = Storage.StoreFile(transferData);

            // Send to the javascript the "to sign hash" of the document (digest of the "to-sign-bytes") and the
            // digest algorithm that must be used on the signature algorithm computation
            ToSignHashField.Value      = Convert.ToBase64String(signatureAlg.DigestAlgorithm.ComputeHash(toSignBytes));
            DigestAlgorithmField.Value = signatureAlg.DigestAlgorithm.Oid;
        }