Go

PDF Sign Unsigned Signature Field

See more PDF Signatures Examples

Demonstrates how to sign a PDF's unsigned signature field.

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

Go

    success := false

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

    pdf := chilkat.NewPdf()

    // Load a PDF containing an unsigned signature field.
    success = pdf.LoadFile("qa_data/pdf/unsigned_sig_field/due_diligence.pdf")
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        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.
    // (image:https://example-code.com/images/unsignedSigField.jpg/endImage)

    // Options for signing are specified in JSON.
    json := chilkat.NewJsonObject()

    // In most cases, the signingCertificateV2 and signingTime attributes are required.
    json.UpdateInt("signingCertificateV2",1)
    json.UpdateInt("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.
    json.UpdateBool("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
    json.UpdateString("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.
    json.UpdateString("appearance.text[0]","Digitally signed by: cert_cn")
    json.UpdateString("appearance.text[1]","current_dt")
    json.UpdateString("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).
    json.UpdateString("appearance.image","green-check-grey-circle")
    json.UpdateString("appearance.imagePlacement","left")

    // Load the signing certificate. (Use your own certificate.)
    cert := chilkat.NewCert()
    success = cert.LoadPfxFile("qa_data/pfx/myPdfSigningCert.pfx","secret")
    if success == false {
        fmt.Println(cert.LastErrorText())
        pdf.DisposePdf()
        json.DisposeJsonObject()
        cert.DisposeCert()
        return
    }

    // Tell the pdf object to use the certificate for signing.
    success = pdf.SetSigningCert(cert)
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        json.DisposeJsonObject()
        cert.DisposeCert()
        return
    }

    success = pdf.SignPdf(json,"qa_output/due_diligence_signed.pdf")
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        json.DisposeJsonObject()
        cert.DisposeCert()
        return
    }

    fmt.Println("The PDF has been successfully cryptographically signed.")

    // The appearance of the signature appears in Adobe Acrobat as shown below.
    // (image:https://example-code.com/images/signature3.jpg/endImage)

    pdf.DisposePdf()
    json.DisposeJsonObject()
    cert.DisposeCert()