Macro signature disappears.

[Guest]

I have several spreadsheets with Macros that I deploy throughout our
school district with security level locked at high. I sign all the macros
for any spreadsheet and have deployed the trust to all computers (done at
HKLM level, so users cannot alter the trusts). By in large this works well.
However, I have some users that, through no fault of their own, manage to
somehow strip the signatures from their document. All macros are password
protected, so they can't alterany code. I can open the document from a
development machine, apply the signature, and then visit their classroom and
work with them without any problem. The next morning, I will get a call that
they were working on it again and the macros are broken again (the signature
is MIA again).
I'm at a loss to explain what they may be doing to cause the signature to
be removed...I can only imagine that something is causing the code to change
and invalidate the signature even though they really can't access it.
So is there any method to further protect the code/certificate to make
sure things don't get changed?

 

[Robin Hammond]

Not sure if this is the answer, but is there any kind of VBA autosave tool
installed on the machines you are having trouble with. Saving a vba project
on a machine that does not hold the original of the certificate could cause
the certificate to be discarded.

Robin Hammond
www.enhanceddatasystems.com

 

[Guest]

I have not found that saving a document that has associated signed VBA code
to drop the signature, unless something has changed the VBA code. There may
be other circumstances that cause the signature to be lost, which I think is
the root of the question, what events will cause the signature to be lost?
There might also be a version issue, like Office 98 vs. Office 2003 or
something like that, though I have not run into problems with signed files
losing signatures other than by users modifying the VBA.

OHHHH yeah.. Just remembered something, if a user adds/edits controls in the
workbook, like adding a text box or editing the functionality of the text box
to the document, then Office considers this a change in VBA functionality and
will drop the signature when saved.

 

[Guest]

Thanks for the reply.

I'll have to take a look at the control issues. I have used a button
control on these forms, perhaps they're moving it or causing some other
modifcation to register.