(Classic ASP) Verify DomainKey-Signature Headers in Downloaded Email

Downloads email from an IMAP server and verifies the DomainKey-Signature header(s) in each email, if present.

Note: DKIM-Signatures are much more common than DomainKey-Signatures. See the other Chilkat example for verifying DKIM-Signatures (link in the code below).

Chilkat ActiveX Downloads

ActiveX for 32-bit and 64-bit Windows

<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> </head> <body> <% ' This example requires the Chilkat API to have been previously unlocked. ' See Global Unlock Sample for sample code. ' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Imap") set imap = Server.CreateObject("Chilkat.Imap") ' Connect to an IMAP server, login, select mailbox.. ' Use TLS imap.Ssl = 1 imap.Port = 993 success = imap.Connect("imap.someMailServer.com") If (success = 1) Then success = imap.Login("myLogin","myPassword") If (success = 1) Then success = imap.SelectMailbox("Inbox") End If End If If (success <> 1) Then Response.Write "<pre>" & Server.HTMLEncode( imap.LastErrorText) & "</pre>" Response.End End If ' Note: DKIM-Signatures are much more common than DomainKey-Signature ' See DKIM-Signature Verify Sample. ' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.Dkim") set dkim = Server.CreateObject("Chilkat.Dkim") ' Download a max of 10 emails and verify any DomainKey-Signature headers ' that are present. ' Download emails by sequence numbers (not UIDs). bUid = 0 n = imap.NumMessages If (n > 50) Then n = 50 End If ' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.JsonObject") set json = Server.CreateObject("Chilkat.JsonObject") json.EmitCompact = 0 ' To verify DomainKey-Signature headers, we need the exact unmodified MIME bytes of each email. ' For versions of Chilkat < 10.0.0, use CreateObject("Chilkat_9_5_0.BinData") set mimeData = Server.CreateObject("Chilkat.BinData") seqNum = 1 Do While seqNum <= n ' The FetchSingleBd method was introduced in v9.5.0.76 success = imap.FetchSingleBd(seqNum,bUid,mimeData) If (success <> 1) Then Response.Write "<pre>" & Server.HTMLEncode( imap.LastErrorText) & "</pre>" Response.End End If ' Note: DKIM-Signatures are much more common than DomainKey-Signature ' See DKIM-Signature Verify Sample. ' Get the number of DomainKey-Signature headers. numSigs = dkim.NumDomainKeySigs(mimeData) ' Verify each.. j = 0 Do While j < numSigs Response.Write "<pre>" & Server.HTMLEncode( "------ DomainKey Signature " & j) & "</pre>" success = dkim.DomainKeyVerify(j,mimeData) If (success <> 1) Then Response.Write "<pre>" & Server.HTMLEncode( "Not valid.") & "</pre>" Response.Write "<pre>" & Server.HTMLEncode( dkim.LastErrorText) & "</pre>" Else Response.Write "<pre>" & Server.HTMLEncode( "valid.") & "</pre>" End If ' Show the additional information about the signature verification success = json.Load(dkim.VerifyInfo) Response.Write "<pre>" & Server.HTMLEncode( json.Emit()) & "</pre>" ' The JSON contains information such as this: ' { ' "domain": "amazonses.com", ' "selector": "7v7vs6w47njt4pimodk5mmttbegzsi6n", ' "publicKey": "MIGfMA0GCSqG...v2GvWPqGHz6uqeQIDAQAB", ' "canonicalization": "relaxed/simple", ' "algorithm": "rsa-sha256", ' "signedHeaders": "Subject:From:To:Date:Mime-Version:Content-Type:References:Message-Id:Feedback-ID", ' "verified": "yes" ' } j = j + 1 Loop seqNum = seqNum + 1 Loop success = imap.Disconnect() %> </body> </html>