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(Unicode C) PDF Sign Under Existing SignatureSee more PDF Signatures ExamplesThis example explains how sign a previously-signed PDF and place the signature appearance below the existing signature. Note: This example requires Chilkat v9.5.0.85 or greater.
#include <C_CkPdfW.h> #include <C_CkJsonObjectW.h> #include <C_CkCertW.h> void ChilkatSample(void) { HCkPdfW pdf; BOOL success; HCkJsonObjectW json; HCkCertW cert; // This example requires the Chilkat API to have been previously unlocked. // See Global Unlock Sample for sample code. pdf = CkPdfW_Create(); // Load a PDF to be signed. success = CkPdfW_LoadFile(pdf,L"qa_data/pdf/sign_testing_4/hello_signed.pdf"); if (success == FALSE) { wprintf(L"%s\n",CkPdfW_lastErrorText(pdf)); CkPdfW_Dispose(pdf); return; } // The PDF we'll be signing already has a signature added in Adobe Acrobat DC. // It looks like this: // (Notice the Adobe background logo, which is commonly what you'll see when a signature // is created by Adobe Acrobat. Chilkat (obviously) does not create signatures using the Adobe // logo because it would be a copyright violation.) // Options for signing are specified in JSON. json = CkJsonObjectW_Create(); // In most cases, the signingCertificateV2 and signingTime attributes are required. CkJsonObjectW_UpdateInt(json,L"signingCertificateV2",1); CkJsonObjectW_UpdateInt(json,L"signingTime",1); // To put our new signature underneath the existing signature, we have to specify the page // where the existing signature is found, and then we can specify "under" for the "appearance.y" CkJsonObjectW_UpdateInt(json,L"page",1); CkJsonObjectW_UpdateString(json,L"appearance.y",L"under"); CkJsonObjectW_UpdateString(json,L"appearance.fontScale",L"10.0"); CkJsonObjectW_UpdateString(json,L"appearance.text[0]",L"Reason: Agreement Accepted by John"); CkJsonObjectW_UpdateString(json,L"appearance.text[1]",L"Date: current_dt"); // Load the signing certificate. (Use your own certificate.) cert = CkCertW_Create(); success = CkCertW_LoadPfxFile(cert,L"qa_data/pfx/myPdfSigningCert.pfx",L"secret"); if (success == FALSE) { wprintf(L"%s\n",CkCertW_lastErrorText(cert)); CkPdfW_Dispose(pdf); CkJsonObjectW_Dispose(json); CkCertW_Dispose(cert); return; } // Tell the pdf object to use the certificate for signing. success = CkPdfW_SetSigningCert(pdf,cert); if (success == FALSE) { wprintf(L"%s\n",CkPdfW_lastErrorText(pdf)); CkPdfW_Dispose(pdf); CkJsonObjectW_Dispose(json); CkCertW_Dispose(cert); return; } // Note: When adding an additional signature to a PDF, the existing signatures // are validated, and this includes validating the certificates previously used to // create the existing signatures. (A signature typically embeds the signing certs.) // In some cases, the certificates and/or certs in the chain of authentication for // existing signatures are not present, and are not available on the current system. // In this case, you can skip the validation by setting this keyword in UncommonOptions: CkPdfW_putUncommonOptions(pdf,L"NO_VERIFY_CERT_SIGNATURES"); success = CkPdfW_SignPdf(pdf,json,L"qa_output/hello_signed.pdf"); if (success == FALSE) { wprintf(L"%s\n",CkPdfW_lastErrorText(pdf)); CkPdfW_Dispose(pdf); CkJsonObjectW_Dispose(json); CkCertW_Dispose(cert); return; } wprintf(L"The PDF has been successfully cryptographically signed.\n"); // Here's a screenshot of the 2nd signature positioned under the 1st in Adobe Acrobat: CkPdfW_Dispose(pdf); CkJsonObjectW_Dispose(json); CkCertW_Dispose(cert); } |
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