(PureBasic) POP3 Verify Signed (S/MIME) Email

Demonstrates how to download and verify digitally signed S/MIME email.

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkStringTable.pb"
IncludeFile "CkCert.pb"
IncludeFile "CkEmail.pb"
IncludeFile "CkMailMan.pb"

Procedure ChilkatExample()

    success.i = 0

    ; This example requires the Chilkat API to have been previously unlocked.
    ; See Global Unlock Sample for sample code.

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

    ; Set the POP3 server's hostname
    CkMailMan::setCkMailHost(mailman, "pop.example.com")

    ; Set the POP3 login/password.
    CkMailMan::setCkPopUsername(mailman, "myLogin")
    CkMailMan::setCkPopPassword(mailman, "myPassword")

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

    success = CkMailMan::ckFetchUidls(mailman,stUidls)
    If success = 0
        Debug CkMailMan::ckLastErrorText(mailman)
        CkMailMan::ckDispose(mailman)
        CkStringTable::ckDispose(stUidls)
        ProcedureReturn
    EndIf

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

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

    count.i = CkStringTable::ckCount(stUidls)
    i.i = 0
    While i < count
        ; Download the full email.
        success = CkMailMan::ckFetchByUidl(mailman,CkStringTable::ckStringAt(stUidls,i),0,0,email)
        If success = 0
            Debug CkMailMan::ckLastErrorText(mailman)
            CkMailMan::ckDispose(mailman)
            CkStringTable::ckDispose(stUidls)
            CkEmail::ckDispose(email)
            CkCert::ckDispose(cert)
            ProcedureReturn
        EndIf

        Debug Str(i)
        Debug "From: " + CkEmail::ckFrom(email)
        Debug "Subject: " + CkEmail::ckSubject(email)

        ; The security layers of signed and/or encrypted emails
        ; are automatically "unwrapped" when loaded into
        ; a Chilkat email object.
        ; An application only needs to check to see if an email
        ; was received signed or encrypted, and then examine
        ; the success/failure.  For example:
        If CkEmail::ckReceivedSigned(email) = 1

            Debug "This email was signed."

            ; Check to see if the signatures were verified.
            If CkEmail::ckSignaturesValid(email) = 1
                Debug "Digital signature(s) verified."
                Debug "Signer: " + CkEmail::ckSignedBy(email)

                success = CkEmail::ckLastSignerCert(email,0,cert)
                If success = 0
                    Debug CkEmail::ckLastErrorText(email)
                    CkMailMan::ckDispose(mailman)
                    CkStringTable::ckDispose(stUidls)
                    CkEmail::ckDispose(email)
                    CkCert::ckDispose(cert)
                    ProcedureReturn
                EndIf

                Debug "Signing cert: " + CkCert::ckSubjectCN(cert)
            EndIf

        Else
            Debug "Digital signature verification failed."
        EndIf

        i = i + 1
    Wend

    CkMailMan::ckPop3EndSession(mailman)


    CkMailMan::ckDispose(mailman)
    CkStringTable::ckDispose(stUidls)
    CkEmail::ckDispose(email)
    CkCert::ckDispose(cert)


    ProcedureReturn
EndProcedure