C

PDF Signature Appearance Text Substitution Keywords

See more PDF Signatures Examples

This example demonstrates the text substitution keywords that can be used in the PDF signature's appearance text.

Note: This example requires Chilkat v9.5.0.85 or greater.

C

#include <C_CkPdf.h>
#include <C_CkJsonObject.h>
#include <C_CkBinData.h>
#include <C_CkCert.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkPdf pdf;
    HCkJsonObject json;
    HCkBinData jpgData;
    HCkCert cert;

    success = FALSE;

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    pdf = CkPdf_Create();

    // Load a PDF to be signed.
    success = CkPdf_LoadFile(pdf,"qa_data/pdf/empty.pdf");
    if (success == FALSE) {
        printf("%s\n",CkPdf_lastErrorText(pdf));
        CkPdf_Dispose(pdf);
        return;
    }

    // Options for signing are specified in JSON.
    json = CkJsonObject_Create();

    // In most cases, the signingCertificateV2 and signingTime attributes are required.
    CkJsonObject_UpdateInt(json,"signingCertificateV2",1);
    CkJsonObject_UpdateInt(json,"signingTime",1);

    // Put the signature on page 1, top left
    CkJsonObject_UpdateInt(json,"page",1);
    CkJsonObject_UpdateString(json,"appearance.y","top");
    CkJsonObject_UpdateString(json,"appearance.x","left");

    // Use a font scale of 7.0
    CkJsonObject_UpdateString(json,"appearance.fontScale","7.0");

    // The appearance of the PDF signature can contain any number of text lines.
    // Chilkat has defined a number of special keywords that can be used in any text line.
    // Each keyword is replaced with the actual value.
    // For example, "cert_cn" is replaced with the certificate subject's common name (CN).

    // Here we are creating a signature with many lines of text, to demonstrate each
    // keyword.
    CkJsonObject_UpdateString(json,"appearance.text[0]","Date/time in PDF format: current_dt");
    CkJsonObject_UpdateString(json,"appearance.text[1]","Current Local date/time: current_datetime");
    CkJsonObject_UpdateString(json,"appearance.text[2]","GMT Timestamp: current_timestamp_gmt");
    CkJsonObject_UpdateString(json,"appearance.text[3]","Local Timestamp: current_timestamp_local");
    CkJsonObject_UpdateString(json,"appearance.text[4]","GMT RFC822 date/time: current_rfc822_dt_gmt");
    CkJsonObject_UpdateString(json,"appearance.text[5]","Local RFC822 date/time: current_rfc822_dt_local");
    CkJsonObject_UpdateString(json,"appearance.text[6]","Cert DN (Distinguished Name): cert_dn");
    CkJsonObject_UpdateString(json,"appearance.text[7]","Cert Common Name: cert_cn");
    CkJsonObject_UpdateString(json,"appearance.text[8]","Cert Organizational ID (2.5.4.97): cert_org_id");
    CkJsonObject_UpdateString(json,"appearance.text[9]","Cert Email: cert_email");
    CkJsonObject_UpdateString(json,"appearance.text[10]","Cert Organization: cert_organization");
    CkJsonObject_UpdateString(json,"appearance.text[11]","Cert Organziational Unit: cert_ou");
    CkJsonObject_UpdateString(json,"appearance.text[12]","Cert State: cert_state");
    CkJsonObject_UpdateString(json,"appearance.text[13]","Cert Country: cert_country");
    CkJsonObject_UpdateString(json,"appearance.text[14]","Cert Locality: cert_locality");
    CkJsonObject_UpdateString(json,"appearance.text[15]","Cert Serial Number (hex): cert_serial_hex");
    CkJsonObject_UpdateString(json,"appearance.text[16]","Cert Serial Number (decimal): cert_serial_dec");
    CkJsonObject_UpdateString(json,"appearance.text[17]","Cert Thumbprint: cert_thumbprint");
    CkJsonObject_UpdateString(json,"appearance.text[18]","Cert Issuer Common Name: cert_issuer_cn");

    jpgData = CkBinData_Create();
    success = CkBinData_LoadFile(jpgData,"qa_data/jpg/seal1.jpg");
    if (success == FALSE) {
        printf("Failed to load the JPG image.\n");
        CkPdf_Dispose(pdf);
        CkJsonObject_Dispose(json);
        CkBinData_Dispose(jpgData);
        return;
    }

    success = CkPdf_SetSignatureJpeg(pdf,jpgData);
    if (success == FALSE) {
        printf("%s\n",CkPdf_lastErrorText(pdf));
        CkPdf_Dispose(pdf);
        CkJsonObject_Dispose(json);
        CkBinData_Dispose(jpgData);
        return;
    }

    // Specify that we want to display the JPG image in the center with 33% opacity.
    CkJsonObject_UpdateString(json,"appearance.image","custom-jpg");
    CkJsonObject_UpdateString(json,"appearance.imagePlacement","center");
    CkJsonObject_UpdateString(json,"appearance.imageOpacity","33");

    // Load the signing certificate. (Use your own certificate.)
    cert = CkCert_Create();
    success = CkCert_LoadPfxFile(cert,"qa_data/pfx/myPdfSigningCert.pfx","pfx_password");
    if (success == FALSE) {
        printf("%s\n",CkCert_lastErrorText(cert));
        CkPdf_Dispose(pdf);
        CkJsonObject_Dispose(json);
        CkBinData_Dispose(jpgData);
        CkCert_Dispose(cert);
        return;
    }

    // Tell the pdf object to use the certificate for signing.
    success = CkPdf_SetSigningCert(pdf,cert);
    if (success == FALSE) {
        printf("%s\n",CkPdf_lastErrorText(pdf));
        CkPdf_Dispose(pdf);
        CkJsonObject_Dispose(json);
        CkBinData_Dispose(jpgData);
        CkCert_Dispose(cert);
        return;
    }

    success = CkPdf_SignPdf(pdf,json,"qa_output/hello_signed.pdf");
    if (success == FALSE) {
        printf("%s\n",CkPdf_lastErrorText(pdf));
        CkPdf_Dispose(pdf);
        CkJsonObject_Dispose(json);
        CkBinData_Dispose(jpgData);
        CkCert_Dispose(cert);
        return;
    }

    printf("The PDF has been successfully cryptographically signed.\n");

    // The appearance of the signature appears in Adobe Acrobat as shown here:

    // (image:https://example-code.com/images/pdf_signature_text_replacements.jpg/endImage)


    CkPdf_Dispose(pdf);
    CkJsonObject_Dispose(json);
    CkBinData_Dispose(jpgData);
    CkCert_Dispose(cert);

    }