Debug Outlook S/MIME

If Outlook cannot decrypt an S/MIME e-mail it displays the error message “Your digital ID name cannot be found by the underlying security system” which does not give any clues as to why. When this happens there is no easy way in Outlook to examine the message and see what certificates it was encrypted for.

To get this information I wrote a small program to scan through an encrypted message and look for data structures that resemble ASN1 sequences and print the Certificate Authority name and the certificate serial numbers. To use it copy the message to a file using click and drag from Outlook to Explorer and run the program in a CMD.EXE window giving the message file as input.

idcert.exe is available for download.