B4X

Get the SMTP or POP3 Server's TLS Certificate

Demonstrates the Chilkat MailMan.GetServerCert method, which gets the digital certificate presented by the SMTP or POP3 server for the current SSL/TLS connection and stores it in a Cert object. Pass true for the SMTP server's certificate or false for the POP3 server's. This example connects to the SMTP server and prints the certificate's subject and issuer.

Background: During a TLS handshake the server presents a certificate proving its identity, and the client validates it against trusted authorities. Retrieving that certificate lets you inspect it yourself — checking the subject, issuer, or expiration for auditing, logging, or certificate-pinning style checks. It must be called while a TLS connection is established, since the certificate belongs to that specific session.

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B4X

Dim success As Boolean = False

'  Demonstrates the MailMan.GetServerCert method, which gets the digital certificate
'  presented by the SMTP or POP3 server for the current SSL/TLS connection.  Pass True for
'  the SMTP server's certificate, or False for the POP3 server's certificate.

Dim mailman As ChilkatMailMan
mailman.Initialize("mailman")

'  Configure the SMTP server connection.
mailman.SmtpHost = "smtp.example.com"
mailman.SmtpPort = 465
mailman.SmtpSsl = True
mailman.SmtpUsername = "user@example.com"
mailman.SmtpPassword = "myPassword"

'  Establish the TLS connection.
success = mailman.SmtpConnect
If success = False Then
    Log(mailman.LastErrorText)
    Return
End If


'  Get the certificate the SMTP server presented (useSmtp = True).
Dim cert As ChilkatCert
cert.Initialize("cert")
success = mailman.GetServerCert(True, cert)
If success = False Then
    Log(mailman.LastErrorText)
    Return
End If


Log("Server certificate subject (CN): " & cert.SubjectCN)
Log("Issued by: " & cert.IssuerCN)

success = mailman.CloseSmtpConnection
If success = False Then
    Log(mailman.LastErrorText)
    Return
End If