(Go) Sign PDF using ARSS (Aruba Remote Signing Service)

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Demonstrates how to digitally sign a PDF using the Aruba Remote Signing Service (ARSS). The example loads a local PDF and certificate, configures the ARSS cloud signer credentials, specifies the OTP authentication type with typeOtpAuth, and creates an LTV-enabled signed PDF where the private key remains protected on the Aruba signing server.

Note: This example requires Chilkat v11.5.0 or greater.

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    success := false

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

    pdf := chilkat.NewPdf()

    // Load the PDF that will be digitally signed.
    success = pdf.LoadFile("qa_data/pdf/hello.pdf")
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        return
    }

    // Signing options are specified in a JSON object.
    json := chilkat.NewJsonObject()

    // Enable LTV (Long-Term Validation).
    // When ltvOcsp is true, OCSP validation information is embedded in the PDF
    // so that signature validation can continue to succeed in the future,
    // even if the original OCSP responder is no longer available.
    json.UpdateBool("ltvOcsp",true)

    // Specify the visual appearance of the signature on the PDF page.
    json.UpdateInt("page",1)
    json.UpdateString("appearance.y","top")
    json.UpdateString("appearance.x","left")
    json.UpdateString("appearance.fontScale","10.0")

    // Text lines displayed in the visible signature appearance.
    // Special values such as "cert_cn" and "current_dt" are replaced
    // with the certificate common name and current date/time.
    json.UpdateString("appearance.text[0]","Digitally signed by: cert_cn")
    json.UpdateString("appearance.text[1]","current_dt")
    json.UpdateString("appearance.text[2]","This is an LTV-enabled signature.")

    // Load the signing certificate.
    // 
    // The private key is NOT stored locally.  Instead, the private key is
    // stored and protected on the Aruba Remote Signing Service (ARSS).
    // 
    // Even though the signing operation will occur remotely, Chilkat still
    // needs the corresponding public certificate locally so that it can
    // construct the CMS/PAdES signature and embed the certificate chain
    // in the signed PDF.
    cert := chilkat.NewCert()
    success = cert.LoadFromFile("qa_data/certs/myCert.cer")
    if success == false {
        fmt.Println(cert.LastErrorText())
        pdf.DisposePdf()
        json.DisposeJsonObject()
        cert.DisposeCert()
        return
    }

    // Configure Aruba Remote Signing Service (ARSS) credentials.
    // 
    // When SetCloudSigner is called, Chilkat is instructed to perform
    // cryptographic signing operations through the ARSS web service.
    // The PDF is assembled locally, but the actual RSA signature operation
    // is performed remotely using the private key held by Aruba.
    jsonArss := chilkat.NewJsonObject()

    // Required.  Indicates that the cloud signing provider is ARSS.
    jsonArss.UpdateString("service","ARSS")

    // The ARSS certificate identifier (for example, "AS0").
    // This identifies which remote certificate/private key pair should be used.
    // The remote certificate should correspond to the certificate loaded above.
    jsonArss.UpdateString("certID","YOUR_ARSS_CERT_ID")

    // OTP password associated with the Aruba remote-signing account.
    // Depending on the ARSS configuration, an OTP may be required to
    // authorize each signing operation.
    jsonArss.UpdateString("otpPwd","YOUR_OTP_PWD")

    // Specifies the OTP authentication environment.
    // 
    // Common values are:
    //   "demoprod" - Demo/Test environment
    //   "prod"     - Production environment
    // 
    // This value is sent to the ARSS service and determines how the OTP
    // authentication is validated.  The correct value depends on the type
    // of Aruba account and environment that has been provisioned.
    // 
    // If signing fails with an authentication-related error, verify that
    // the typeOtpAuth value matches the environment associated with the
    // ARSS account credentials being used.
    jsonArss.UpdateString("typeOtpAuth","demoprod")

    // ARSS account username.
    jsonArss.UpdateString("user","YOUR_ARSS_USERNAME")

    // ARSS account password.
    jsonArss.UpdateString("userPWD","YOUR_ARSS_PASSWORD")

    // Beginning with Chilkat v11.5.0, the ARSS endpoint can be explicitly
    // specified.  This allows the application to target a particular
    // Aruba signing service endpoint when required.
    jsonArss.UpdateString("endpoint","https://app1.firma-remota.it/ArubaSignerService/webresources/signerservice")

    success = cert.SetCloudSigner(jsonArss)
    if success == false {
        fmt.Println(cert.LastErrorText())
        pdf.DisposePdf()
        json.DisposeJsonObject()
        cert.DisposeCert()
        jsonArss.DisposeJsonObject()
        return
    }

    // Associate the certificate with the PDF object.
    // All subsequent signing operations will use this certificate.
    success = pdf.SetSigningCert(cert)
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        json.DisposeJsonObject()
        cert.DisposeCert()
        jsonArss.DisposeJsonObject()
        return
    }

    // Create the signed PDF.
    // 
    // Chilkat performs all PDF processing locally.  When the time comes
    // to generate the cryptographic signature value, Chilkat sends the
    // hash to ARSS, which signs it using the remote private key and returns
    // the signature.  The private key never leaves the Aruba service.
    success = pdf.SignPdf(json,"qa_output/hello_ltv_signed.pdf")
    if success == false {
        fmt.Println(pdf.LastErrorText())
        pdf.DisposePdf()
        json.DisposeJsonObject()
        cert.DisposeCert()
        jsonArss.DisposeJsonObject()
        return
    }

    fmt.Println("The PDF has been successfully cryptographically signed with long-term validation.")

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