(DataFlex) PDF Sign Under Existing Signature
This 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.
Use ChilkatAx-win32.pkg
Procedure Test
Handle hoPdf
Boolean iSuccess
Variant vJson
Handle hoJson
Variant vCert
Handle hoCert
String sTemp1
// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.
Get Create (RefClass(cComChilkatPdf)) To hoPdf
If (Not(IsComObjectCreated(hoPdf))) Begin
Send CreateComObject of hoPdf
End
// Load a PDF to be signed.
Get ComLoadFile Of hoPdf "qa_data/pdf/sign_testing_4/hello_signed.pdf" To iSuccess
If (iSuccess = False) Begin
Get ComLastErrorText Of hoPdf To sTemp1
Showln sTemp1
Procedure_Return
End
// 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.
Get Create (RefClass(cComChilkatJsonObject)) To hoJson
If (Not(IsComObjectCreated(hoJson))) Begin
Send CreateComObject of hoJson
End
// In most cases, the signingCertificateV2 and signingTime attributes are required.
Get ComUpdateInt Of hoJson "signingCertificateV2" 1 To iSuccess
Get ComUpdateInt Of hoJson "signingTime" 1 To iSuccess
// 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"
Get ComUpdateInt Of hoJson "page" 1 To iSuccess
Get ComUpdateString Of hoJson "appearance.y" "under" To iSuccess
Get ComUpdateString Of hoJson "appearance.fontScale" "10.0" To iSuccess
Get ComUpdateString Of hoJson "appearance.text[0]" "Reason: Agreement Accepted by John" To iSuccess
Get ComUpdateString Of hoJson "appearance.text[1]" "Date: current_dt" To iSuccess
// Load the signing certificate. (Use your own certificate.)
Get Create (RefClass(cComChilkatCert)) To hoCert
If (Not(IsComObjectCreated(hoCert))) Begin
Send CreateComObject of hoCert
End
Get ComLoadPfxFile Of hoCert "qa_data/pfx/myPdfSigningCert.pfx" "secret" To iSuccess
If (iSuccess = False) Begin
Get ComLastErrorText Of hoCert To sTemp1
Showln sTemp1
Procedure_Return
End
// Tell the pdf object to use the certificate for signing.
Get pvComObject of hoCert to vCert
Get ComSetSigningCert Of hoPdf vCert To iSuccess
If (iSuccess = False) Begin
Get ComLastErrorText Of hoPdf To sTemp1
Showln sTemp1
Procedure_Return
End
// 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:
Set ComUncommonOptions Of hoPdf To "NO_VERIFY_CERT_SIGNATURES"
Get pvComObject of hoJson to vJson
Get ComSignPdf Of hoPdf vJson "qa_output/hello_signed.pdf" To iSuccess
If (iSuccess = False) Begin
Get ComLastErrorText Of hoPdf To sTemp1
Showln sTemp1
Procedure_Return
End
Showln "The PDF has been successfully cryptographically signed."
// Here's a screenshot of the 2nd signature positioned under the 1st in Adobe Acrobat:
End_Procedure
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