Classic ASP

Get Recipient Certificate Info from Encrypted S/MIME

Demonstrates GetDecryptCertInfo, which examines an encrypted S/MIME entity and writes the recipient-certificate identifiers into a JsonObject. This reveals which certificate(s) the message was encrypted for, so the correct private key can be located before decrypting.

The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Tip: Code to parse the returned JSON can be generated with Chilkat's online tool at https://tools.chilkat.io/jsonParse.

Background. A CMS/PKCS #7 encrypted message carries recipient identifiers (such as issuer and serial number). Inspecting them lets an application determine, without decrypting, which key it needs.

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Classic ASP

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<%
success = 0

set mime = Server.CreateObject("Chilkat.Mime")
success = mime.LoadMimeFile("qa_data/encrypted.eml")
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( mime.LastErrorText) & "</pre>"
    Response.End
End If

'  Examine the encrypted entity and write the recipient-certificate identifiers to a JsonObject.
'  This tells you which certificate(s) the message was encrypted for, so you can locate the right
'  private key before attempting to decrypt.
set certInfo = Server.CreateObject("Chilkat.JsonObject")
success = mime.GetDecryptCertInfo(certInfo)
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( mime.LastErrorText) & "</pre>"
    Response.End
End If

certInfo.EmitCompact = 0
json = certInfo.Emit()
Response.Write "<pre>" & Server.HTMLEncode( json) & "</pre>"
'  JSON parsing code for this result can be generated at Chilkat's online tool:
'  https://tools.chilkat.io/jsonParse

%>
</body>
</html>