Weird Outlook Encryption Problem

[Zia Texas]

In the past week, Outlook has started generating an error message when we
attempt to open an encrypted message.

We have been using VeriSign certificates since March 2002, have updated them
annually, and have been through several versions of Outlook, starting with
Outlook 2000. I am currently using Outlook 2007 with a VeriSign certificate
expiring in August 2008 and have been using Outlook 2007 since June 2007. My
correspondent is using Outlook 2003 with a VeriSign certificate expiring in
December 2008 and has been using Outlook 2003 for a couple of years. Neither
of us has upgraded the Microsoft software in the past week other than any
Automatic Updates issued by Microsoft.

Neither of us has a problem encrypting a message to the other. The problem
comes when the recipient opens the encrypted message.

We both get a dialog box with the title "Encryption Problems" that says:
Microsoft Office Outlook had problem encrypting this message because the
following recipients had missing or invalid certificates, or conflicting or
unsupported encryption capabilities: (name of the recipient, i.e., me on my
machine and my correspondent on his machine). Continue will encrypt and send
the message but the listed recipients may not be able to read it.

The "Send Encrypted" button is enabled, the "Continue" button is disabled,
and the "Cancel" button is enabled.

Please note that neither of us are attempting to "send" an encrypted message
at this point; we are trying to open and decrypt an encrypted message sent to
us (encrypted using our public key and decrypted with our private key).

If either of us presses either the "Send Unencrypted" button or the "Cancel"
button, the message is decrypted and opened for viewing. However, we've
noticed that the message has been converted from "HTML" format to "Plain
Text.

Has anyone else encountered this problem and know of a way to fix it?

 

[Brian Tillman]

Neither of us has a problem encrypting a message to the other. The
problem comes when the recipient opens the encrypted message.

We both get a dialog box with the title "Encryption Problems" that
says: Microsoft Office Outlook had problem encrypting this message
because the following recipients had missing or invalid certificates,
or conflicting or unsupported encryption capabilities: (name of the
recipient, i.e., me on my machine and my correspondent on his
machine). Continue will encrypt and send the message but the listed
recipients may not be able to read it.

The "Send Encrypted" button is enabled, the "Continue" button is
disabled, and the "Cancel" button is enabled.

Please note that neither of us are attempting to "send" an encrypted
message at this point; we are trying to open and decrypt an encrypted
message sent to us (encrypted using our public key and decrypted with
our private key).

Trying to send a read receipt, perhaps?

 

[Zia Texas]

No, that doesn't seem to be the problem.

Both of us have checked and under the Tracking Options the "Process receipts
on arrival" and "After Processing, move receipts to Deleted Items" boxes were
checked, along with "Ask me before sending a response". We have deleted the
check mark on the first two and changed the last option to "Never Send a
Response"; the problem continues.

Both of us have deleted our personal certificates (private keys) and deleted
the other's certificates (public keys), downloaded them again from the
VeriSign web site and reinstaled them in IE (private key) and Outlook (public
key for contact), respectively. We've also checked our Security Settings and
we're using:

My S/MIME Settings (name)
Cryptography Format: S/MIME
(Checked) Default Security Setting for this cryptographic message format
(Cheecked) Default Security Setting for all cryptographic messages

Signing Certificate (Our name)
Hash Algorithm: SHA1
Encryption Certificate (Our name)
Encryption Algorithm: AES (256-bit)

(Checked) Send thse certificates with signed messages

We do not have any of the Encrypted Email options checked under the Trust
Center (E-mail Security).