(Go) Sign a PDF using SmartCard or HSM (Hardware Security Module)

See more PDF Signatures Examples

This example demonstrates how to a sign a PDF using a smartcard or HSM (hardware security module).

Note: This example requires Chilkat v9.5.0.88 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.
    // The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
    success := pdf.LoadFile("qa_data/pdf/hello.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 10.0
    json.UpdateString("appearance.fontScale","10.0")

    // 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.")

    // Use a certificate on a smartcard or USB token.
    cert := chilkat.NewCert()

    // Provide the smartcard PIN.
    // Set the smartcard PIN prior to calling LoadFromSmartcard.
    // If the PIN is not explicitly provided here, the Windows OS should
    // display a dialog for the PIN.
    cert.SetSmartCardPin("123456")

    // Load the certificate on the smartcard currently in the reader (or on the USB token).
    // Pass an empty string to allow Chilkat to automatically choose the CSP (Cryptographi Service Provider).
    // See Load Certificate on Smartcard for information about explicitly selecting a particular CSP.
    success = cert.LoadFromSmartcard("")
    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/hello_signed_hsm.pdf")
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        json.DisposeJsonObject()
        cert.DisposeCert()
        return
    }

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

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