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(C) PDF Sign Unsigned Signature Field
Demonstrates how to sign a PDF's unsigned signature field.
Note: This example requires Chilkat v9.5.0.85 or greater.
#include <C_CkPdf.h>
#include <C_CkJsonObject.h>
#include <C_CkCert.h>
void ChilkatSample(void)
{
HCkPdf pdf;
BOOL success;
HCkJsonObject json;
HCkCert cert;
// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.
pdf = CkPdf_Create();
// Load a PDF containing an unsigned signature field.
success = CkPdf_LoadFile(pdf,"qa_data/pdf/unsigned_sig_field/due_diligence.pdf");
if (success == FALSE) {
printf("%s\n",CkPdf_lastErrorText(pdf));
CkPdf_Dispose(pdf);
return;
}
// A PDF with an unsigned signature field appears in Adobe Acrobat as shown below.
// (When the mouse pointer is hovered over the field, a tooltip will likely show a message
// such as "Unsigned signature field (Click to sign)".
// This example code will automatically find the unsigned signature field,
// and signs using your certificate. It automatically sizes the text to the space alotted
// for the signature.
// 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);
// We don't specify the page or a specific location because Chilkat will automatically
// find the unsigned signature field and use its location and size and will scale the
// signatures visual appearance (text + graphics) to the correct size required to fit.
// We only need to indicate the desire to fill the unsigned signature field.
CkJsonObject_UpdateBool(json,"appearance.fillUnsignedSignatureField",TRUE);
// Starting in Chilkat v9.5.0.90, if a PDF contains multiple unsigned signature fields,
// the field to be signed can be chosen by name:
// To list unsigned signature fields, see this example: List PDF Unsigned Signature Fields
CkJsonObject_UpdateString(json,"unsignedSignatureField","doctor_signature");
// Note: If the PDF document contains multiple unsigned signature fields, Chilkat will
// sign the 1st one found.
// In this example, the appearance of the digital signature will contain three lines:
// 1) The signing certificate's common name
// 2) The current date/time
// 3) Some arbitrary text.
// The keyword "cert_cn" is replaced with the Certificate's Subject Common Name.
// The keyword "current_dt" is replaced with the current date/time.
// Any number of appearance text lines can be added.
CkJsonObject_UpdateString(json,"appearance.text[0]","Digitally signed by: cert_cn");
CkJsonObject_UpdateString(json,"appearance.text[1]","current_dt");
CkJsonObject_UpdateString(json,"appearance.text[2]","The crazy brown fox jumps over the lazy dog.");
// This signature will include one of the built-in SVG graphics (green-check-grey-circle).
CkJsonObject_UpdateString(json,"appearance.image","green-check-grey-circle");
CkJsonObject_UpdateString(json,"appearance.imagePlacement","left");
// Load the signing certificate. (Use your own certificate.)
cert = CkCert_Create();
success = CkCert_LoadPfxFile(cert,"qa_data/pfx/myPdfSigningCert.pfx","secret");
if (success == FALSE) {
printf("%s\n",CkCert_lastErrorText(cert));
CkPdf_Dispose(pdf);
CkJsonObject_Dispose(json);
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);
CkCert_Dispose(cert);
return;
}
success = CkPdf_SignPdf(pdf,json,"qa_output/due_diligence_signed.pdf");
if (success == FALSE) {
printf("%s\n",CkPdf_lastErrorText(pdf));
CkPdf_Dispose(pdf);
CkJsonObject_Dispose(json);
CkCert_Dispose(cert);
return;
}
printf("The PDF has been successfully cryptographically signed.\n");
// The appearance of the signature appears in Adobe Acrobat as shown below.
CkPdf_Dispose(pdf);
CkJsonObject_Dispose(json);
CkCert_Dispose(cert);
}
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