Use a TLS Client Certificate

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Demonstrates the Chilkat MailMan.SetSslClientCert method, which sets the client-side certificate to use for SSL/TLS connections. This is typically not required — most SSL/TLS connections authenticate the server only. This example loads a client certificate from a PFX and uses it when connecting.

Background: In an ordinary TLS handshake only the server presents a certificate, and the client proves who it is later with a password. Mutual TLS adds a second leg: the client also presents a certificate, so it is authenticated cryptographically at the transport layer. Some corporate or high-security mail servers require this. Because the client must prove possession of the key, the certificate needs its private key — hence loading from a PFX.

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    success := false

    //  Demonstrates the MailMan.SetSslClientCert method, which sets the client-side certificate
    //  to use for SSL/TLS connections.  This is typically not required -- most SSL/TLS
    //  connections authenticate the server only.

    mailman := chilkat.NewMailMan()

    //  Configure the SMTP server connection.
    mailman.SetSmtpHost("smtp.example.com")
    mailman.SetSmtpPort(465)
    mailman.SetSmtpSsl(true)
    mailman.SetSmtpUsername("user@example.com")
    mailman.SetSmtpPassword("myPassword")

    //  Load the client certificate (with its private key) from a PFX file.
    cert := chilkat.NewCert()
    success = cert.LoadPfxFile("qa_data/certs/client.pfx","pfx_password")
    if success == false {
        fmt.Println(cert.LastErrorText())
        mailman.DisposeMailMan()
        cert.DisposeCert()
        return
    }

    //  Use this certificate to identify the client during the TLS handshake.
    success = mailman.SetSslClientCert(cert)
    if success == false {
        fmt.Println(mailman.LastErrorText())
        mailman.DisposeMailMan()
        cert.DisposeCert()
        return
    }

    success = mailman.VerifySmtpLogin()
    if success == false {
        fmt.Println(mailman.LastErrorText())
        mailman.DisposeMailMan()
        cert.DisposeCert()
        return
    }

    fmt.Println("Connected using a TLS client certificate.")

    //  Note: The path "qa_data/certs/client.pfx" is a relative local filesystem path,
    //  relative to the current working directory of the running application.

    mailman.DisposeMailMan()
    cert.DisposeCert()