(Classic ASP) 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

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' 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")
set dkim = Server.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..
dkim.DkimDomain = "chilkatsoft.com"
dkim.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.
password = "optionalPassword"
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.PrivateKey")
set privKey = Server.CreateObject("Chilkat.PrivateKey")
success = privKey.LoadAnyFormatFile("myPrivateKey.pem",password)
If (success <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( privKey.LastErrorText) & "</pre>"
    Response.End
End If

success = dkim.SetDkimPrivateKey(privKey)
If (success <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( dkim.LastErrorText) & "</pre>"
    Response.End
End If

' Load a MIME file into a byte array.
' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.FileAccess")
set fac = Server.CreateObject("Chilkat.FileAccess")

mimeData = fac.ReadEntireFile("testMessage.eml")
If (fac.LastMethodSuccess <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( fac.LastErrorText) & "</pre>"
    Response.End
End If

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

dkimSignedMime = dkim.AddDkimSignature(mimeData)
If (dkim.LastMethodSuccess <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( dkim.LastErrorText) & "</pre>"
    Response.End
End If

success = fac.WriteEntireFile("dkimSigned.eml",dkimSignedMime)
If (success <> 1) Then
    Response.Write "<pre>" & Server.HTMLEncode( fac.LastErrorText) & "</pre>"
    Response.End
End If

Response.Write "<pre>" & Server.HTMLEncode( "Success.") & "</pre>"

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