Tcl

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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Tcl


load ./chilkat.dll

set success 0

#  Demonstrates the MailMan.GetServerCert method, which gets the digital certificate
#  presented by the SMTP or POP3 server for the current SSL/TLS connection.  Pass 1 for
#  the SMTP server's certificate, or 0 for the POP3 server's certificate.

set mailman [new_CkMailMan]

#  Configure the SMTP server connection.
CkMailMan_put_SmtpHost $mailman "smtp.example.com"
CkMailMan_put_SmtpPort $mailman 465
CkMailMan_put_SmtpSsl $mailman 1
CkMailMan_put_SmtpUsername $mailman "user@example.com"
CkMailMan_put_SmtpPassword $mailman "myPassword"

#  Establish the TLS connection.
set success [CkMailMan_SmtpConnect $mailman]
if {$success == 0} then {
    puts [CkMailMan_lastErrorText $mailman]
    delete_CkMailMan $mailman
    exit
}

#  Get the certificate the SMTP server presented (useSmtp = cktrue).
set cert [new_CkCert]

set success [CkMailMan_GetServerCert $mailman 1 $cert]
if {$success == 0} then {
    puts [CkMailMan_lastErrorText $mailman]
    delete_CkMailMan $mailman
    delete_CkCert $cert
    exit
}

puts "Server certificate subject (CN): [CkCert_subjectCN $cert]"
puts "Issued by: [CkCert_issuerCN $cert]"

set success [CkMailMan_CloseSmtpConnection $mailman]
if {$success == 0} then {
    puts [CkMailMan_lastErrorText $mailman]
    delete_CkMailMan $mailman
    delete_CkCert $cert
    exit
}


delete_CkMailMan $mailman
delete_CkCert $cert