InfoPath Dev

So I have been able to create a digital certificate and sign and then deploy a trusted form in a test lab. In the real deployment we would purchase a code signing certifiate from a CA.

My question is this, since the certifiates that are used expire, what happens to the form when they expire? Do we need to re-publish the form, with a new code certificate?

And then since the form would be re-published, what happens to the forms that have been signed by users using their personal digital certificates? I know you cannot upgrade a template if existing forms in that library have been signed because it will invalidate those existing forms.

So would I be better to use an MSI since that does not require a certifate to make it trusted and thus the form would not need to be upgraded just to renew it.

Thanks

Lee

Hi Lee,
Great question and the first time I have heard this asked. :) First off, I recommend against full trust. Full trust complicates deployment. If, as it sounds, you have already, jumped those hurdles, then the code signing certificate will have to be renewed and reattached to the form which means you will have to republish when it expires.

Users use different digi-certs to sign forms. Those will not be affected by template changes. I am actually surprised to hear that you say the template cannot be upgraded since it will invalidate the existing forms. Not sure I follow that logic. Auto-upgrade should work. Signing the template only affects security of the template, not of the data. So, I think this is a red herring.

If you can remove the full trust requirement that would be best. Otherwise, I think the MSI is more work since it requires an install whereas the digicert has a more web-automated install. It's 6 of one / half a dozen of the other. Not sure you can say which is better. MSI is cheaper since you don't need to buy a code signing cert.

Patrick Halstead [InfoPath MVP]
InfoPathDev

Hi Patrick,

I would have liked to stay with semi-trusted forms, but the client wanted more functionality.

I have tested what you describe and it worked. If I only changed the certificate that the form was signed with then the form remained intact and the digitial certificates on the existing forms remained valid.

However, I also tested adding one new text box and republishing the form with the same certificate. This did have the problem where the existing forms had their digital signatures invalidated. I have screen shots of this I can email you if you'd like.

Lee

Hi Lee,
That is interesting. I guess that does make some sense since you are republishing and the certificate checking logic checks the version of the form. Sounds like a by design issue. I guess auto-upgrade doesn't work and I was wrong. I will follow up with MS and reply back.

Patrick Halstead [InfoPath MVP]
InfoPathDev

Hi again,

Microsoft responded and pointed out a real obvious thing that I should have figured out on my own:

“adding one new text box” caused existing forms to have their digital signatures invalidated. By adding the textbox did you modify your solution schema in such a way that all the old documents must have their XML updated in order to remain schema-valid (which would invalidate the signature)? Make sure that the text box is added as optional (or minOccurs=0) so this doesn't happen. Otherwise, it is by design.

Hope this helps.

Patrick Halstead [InfoPath MVP]
InfoPathDev

In addition, I think you are aware of this, but keep in mind that certificates can expire"

Expired certificates – If the certificate you used expires, you will need to re-sign with a different certificate when you update the form and the clients will need to re-install/re-trust that new certificate. That#%92s pretty standard stuff though and shouldn#%92t affect 99.9% of solution auto-updates

Patrick Halstead [InfoPath MVP]
InfoPathDev