(Visual FoxPro) Add DKIM-Signature Header to MIME / Email

Demonstrates how to add a DKIM-Signature header field to a MIME message.

Note: The DKIM / DomainKey functionality is included with the Chilkat MIME license.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL loDkim
LOCAL lcPassword
LOCAL loPrivKey
LOCAL lnSuccess
LOCAL loFac
LOCAL loMimeData
LOCAL loDkimSignedMime

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

* Important: It is helpful to send the contents of the
* dkim.LastErrorText property when requesting support.

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Dkim')
loDkim = CreateObject('Chilkat.Dkim')

* To create a DKIM signature for email (i.e. MIME),
* you'll need to provide the following:
* (1) An RSA private key in any common file format.
* (2) The domain name (typically the same domain
* as the sender of an email).
* (3) A selector for the domain name -- an arbitrary string
* to identify the matching public key in DNS.

* To allow an email recipient to verify the DKIM signature via an
* external email client supporting DKIM or using other software,
* you will need to create a DNS record with the selector
* and matching public key.  This example does not provide
* information about DKIM DNS record creation.  
* (Chilkat does not provide an API for creating DNS records.  
* Creating the DKIM DNS record is something you would do
* manually.)

* Set the domain and selector:
* You'll need to provide your own values here..
loDkim.DkimDomain = "chilkatsoft.com"
loDkim.DkimSelector = "tuna"

* Load a private key from any common RSA private key
* format, such as DER, PKCS8, PEM, XML, etc.
* The LoadDkimPkFile method automatically detects
* the file format and reads it appropriately.
* If a password is not required, you'll still need to provide
* a password string argument, but it is ignored.
lcPassword = "optionalPassword"
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.PrivateKey')
loPrivKey = CreateObject('Chilkat.PrivateKey')
lnSuccess = loPrivKey.LoadAnyFormatFile("myPrivateKey.pem",lcPassword)
IF (lnSuccess <> 1) THEN
    ? loPrivKey.LastErrorText
    RELEASE loDkim
    RELEASE loPrivKey
    CANCEL
ENDIF

lnSuccess = loDkim.SetDkimPrivateKey(loPrivKey)
IF (lnSuccess <> 1) THEN
    ? loDkim.LastErrorText
    RELEASE loDkim
    RELEASE loPrivKey
    CANCEL
ENDIF

* Load a MIME file into a byte array.
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.FileAccess')
loFac = CreateObject('Chilkat.FileAccess')

loMimeData = loFac.ReadEntireFile("testMessage.eml")
IF (loFac.LastMethodSuccess <> 1) THEN
    ? loFac.LastErrorText
    RELEASE loDkim
    RELEASE loPrivKey
    RELEASE loFac
    CANCEL
ENDIF

* Sign it.  This adds the DKIM-Signature header and
* returns the new MIME with DKIM-Signature added.

loDkimSignedMime = loDkim.AddDkimSignature(loMimeData)
IF (loDkim.LastMethodSuccess <> 1) THEN
    ? loDkim.LastErrorText
    RELEASE loDkim
    RELEASE loPrivKey
    RELEASE loFac
    CANCEL
ENDIF

lnSuccess = loFac.WriteEntireFile("dkimSigned.eml",loDkimSignedMime)
IF (lnSuccess <> 1) THEN
    ? loFac.LastErrorText
    RELEASE loDkim
    RELEASE loPrivKey
    RELEASE loFac
    CANCEL
ENDIF

? "Success."

RELEASE loDkim
RELEASE loPrivKey
RELEASE loFac