(Go) Sign String to create a CAdES-T Signature

This example will sign a string to create a CAdEST-T signature.

Note: This example requires Chilkat v9.5.0.78 or greater.

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

    crypt := chilkat.NewCrypt2()

    // This example will use the certificate + private key currently inserted into a smartcard reader.
    cert := chilkat.NewCert()

    // If we wish to provide the smartcard PIN (otherwise the user will be prompted by the operating system).
    cert.SetSmartCardPin("000000")
    success := cert.LoadFromSmartcard("")
    if success != true {
        fmt.Println(cert.LastErrorText())
        crypt.DisposeCrypt2()
        cert.DisposeCert()
        return
    }

    // Note: It is also possible to use certs from .pfx/.p12, .pem, or other sources such as 
    // pre-installed Windows certificates.

    success = crypt.SetSigningCert(cert)

    // Use SHA-256 rather than the default of SHA-1
    crypt.SetHashAlgorithm("sha256")

    // Create JSON that tells Chilkat what signing attributes to include:
    attrs := chilkat.NewJsonObject()
    attrs.UpdateBool("contentType",true)
    attrs.UpdateBool("signingTime",true)
    attrs.UpdateBool("messageDigest",true)
    attrs.UpdateBool("signingCertificateV2",true)

    // A CAdES-T signature is one that includes a timestampToken created by an online TSA (time stamping authority).
    // We must include the TSA's URL, as well as a few options to indicate what is desired.
    // Except for the TSA URL, the options shown here are typically what you would need.
    attrs.UpdateBool("timestampToken.enabled",true)
    attrs.UpdateString("timestampToken.tsaUrl","https://freetsa.org/tsr")
    attrs.UpdateBool("timestampToken.addNonce",false)
    attrs.UpdateBool("timestampToken.requestTsaCert",true)
    attrs.UpdateString("timestampToken.hashAlg","sha256")

    crypt.SetSigningAttributes(*attrs.Emit())

    strToSign := "THIS IS MY ID"

    bd := chilkat.NewBinData()
    bd.AppendString(strToSign,"utf-8")

    // This creates the CAdES-T signature.  During the signature creation, it
    // communicates with the TSA to get a timestampToken.
    // The contents of bd are signed and replaced with the CAdES-T signature (which embeds the original content).
    success = crypt.OpaqueSignBd(bd)
    if success != true {
        fmt.Println(crypt.LastErrorText())
        crypt.DisposeCrypt2()
        cert.DisposeCert()
        attrs.DisposeJsonObject()
        bd.DisposeBinData()
        return
    }

    // Get the signature in base64 format:
    fmt.Println(*bd.GetEncoded("base64_mime"))

    // Or save the signature to a file.
    bd.WriteFile("qa_output/cades-t_sample.p7m")

    fmt.Println("Success.")

    crypt.DisposeCrypt2()
    cert.DisposeCert()
    attrs.DisposeJsonObject()
    bd.DisposeBinData()