Visual FoxPro

Use a TLS Client Certificate

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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LOCAL lnSuccess
LOCAL loMailman
LOCAL loCert

lnSuccess = 0

*  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.

loMailman = CreateObject('Chilkat.MailMan')

*  Configure the SMTP server connection.
loMailman.SmtpHost = "smtp.example.com"
loMailman.SmtpPort = 465
loMailman.SmtpSsl = 1
loMailman.SmtpUsername = "user@example.com"
loMailman.SmtpPassword = "myPassword"

*  Load the client certificate (with its private key) from a PFX file.
loCert = CreateObject('Chilkat.Cert')
lnSuccess = loCert.LoadPfxFile("qa_data/certs/client.pfx","pfx_password")
IF (lnSuccess = 0) THEN
    ? loCert.LastErrorText
    RELEASE loMailman
    RELEASE loCert
    CANCEL
ENDIF

*  Use this certificate to identify the client during the TLS handshake.
lnSuccess = loMailman.SetSslClientCert(loCert)
IF (lnSuccess = 0) THEN
    ? loMailman.LastErrorText
    RELEASE loMailman
    RELEASE loCert
    CANCEL
ENDIF

lnSuccess = loMailman.VerifySmtpLogin()
IF (lnSuccess = 0) THEN
    ? loMailman.LastErrorText
    RELEASE loMailman
    RELEASE loCert
    CANCEL
ENDIF

? "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.

RELEASE loMailman
RELEASE loCert