(Go) 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.

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

    pdf := chilkat.NewPdf()

    // Load a PDF to be signed.
    success := pdf.LoadFile("qa_data/pdf/empty.pdf")
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        return
    }

    // 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)

    // Put the signature on page 1, top left
    json.UpdateInt("page",1)
    json.UpdateString("appearance.y","top")
    json.UpdateString("appearance.x","left")

    // Use a font scale of 7.0
    json.UpdateString("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.
    json.UpdateString("appearance.text[0]","Date/time in PDF format: current_dt")
    json.UpdateString("appearance.text[1]","Current Local date/time: current_datetime")
    json.UpdateString("appearance.text[2]","GMT Timestamp: current_timestamp_gmt")
    json.UpdateString("appearance.text[3]","Local Timestamp: current_timestamp_local")
    json.UpdateString("appearance.text[4]","GMT RFC822 date/time: current_rfc822_dt_gmt")
    json.UpdateString("appearance.text[5]","Local RFC822 date/time: current_rfc822_dt_local")
    json.UpdateString("appearance.text[6]","Cert DN (Distinguished Name): cert_dn")
    json.UpdateString("appearance.text[7]","Cert Common Name: cert_cn")
    json.UpdateString("appearance.text[8]","Cert Organizational ID (2.5.4.97): cert_org_id")
    json.UpdateString("appearance.text[9]","Cert Email: cert_email")
    json.UpdateString("appearance.text[10]","Cert Organization: cert_organization")
    json.UpdateString("appearance.text[11]","Cert Organziational Unit: cert_ou")
    json.UpdateString("appearance.text[12]","Cert State: cert_state")
    json.UpdateString("appearance.text[13]","Cert Country: cert_country")
    json.UpdateString("appearance.text[14]","Cert Locality: cert_locality")
    json.UpdateString("appearance.text[15]","Cert Serial Number (hex): cert_serial_hex")
    json.UpdateString("appearance.text[16]","Cert Serial Number (decimal): cert_serial_dec")
    json.UpdateString("appearance.text[17]","Cert Thumbprint: cert_thumbprint")
    json.UpdateString("appearance.text[18]","Cert Issuer Common Name: cert_issuer_cn")

    jpgData := chilkat.NewBinData()
    success = jpgData.LoadFile("qa_data/jpg/seal1.jpg")
    if success == false {
        fmt.Println("Failed to load the JPG image.")
        pdf.DisposePdf()
        json.DisposeJsonObject()
        jpgData.DisposeBinData()
        return
    }

    success = pdf.SetSignatureJpeg(jpgData)
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        json.DisposeJsonObject()
        jpgData.DisposeBinData()
        return
    }

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

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

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

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

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

    

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