PureBasic

Get the Server Certificate from a TLS Connection

Demonstrates Socket.GetServerCert, which copies the certificate presented by the remote TLS server into a Cert object for inspection.

Background. The method returns false when the socket is not connected, is not using TLS, or no server certificate is available. Inspecting the certificate lets an application validate the server's identity.

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PureBasic

IncludeFile "CkSocket.pb"
IncludeFile "CkCert.pb"

Procedure ChilkatExample()

    success.i = 0

    socket.i = CkSocket::ckCreate()
    If socket.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ;  Connect to the server using TLS.
    bTls.i = 1
    maxWaitMs.i = 5000
    success = CkSocket::ckConnect(socket,"example.com",5000,bTls,maxWaitMs)
    If success = 0
        Debug CkSocket::ckLastErrorText(socket)
        CkSocket::ckDispose(socket)
        ProcedureReturn
    EndIf

    ;  Copy the certificate presented by the remote TLS server, then inspect it.  This can be used to
    ;  validate the server's identity.
    cert.i = CkCert::ckCreate()
    If cert.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkSocket::ckGetServerCert(socket,cert)
    If success = 0
        Debug CkSocket::ckLastErrorText(socket)
        CkSocket::ckDispose(socket)
        CkCert::ckDispose(cert)
        ProcedureReturn
    EndIf

    Debug "Server certificate subject: " + CkCert::ckSubjectCN(cert)
    Debug "Issued by: " + CkCert::ckIssuerCN(cert)


    CkSocket::ckDispose(socket)
    CkCert::ckDispose(cert)


    ProcedureReturn
EndProcedure