Multiple signatures in a PDF - without invalidating the previous ones

Assuming the form is designed correctly, applyoing a second signature to a signed PDF will not "invalidate" the first signature, it will change the status of the first signature to something like "Valid with signed changes", this is expected behaviour.  Digital Signatures are meant to let you know when something has changed since it was signed.

Is your second signature actually invalidating the first suignature or just changing it's status?  You can post the form or a screen shot of the signature status to help clarify your issue.

Regards

Steve

I have found something that works for me when delaing with forms with multiple signatures and the first shows up as not valid.  Click on the first signature, the click on "Signature Properties", then "Show Certificate".  Go to the "Trust" tab and click "Add to Trusted Identities" at the bottom of the box, then "OK".  Then when that box diappears, click "Validate Signature" at the bottom of the box.  This creates a certificate on your computer that will validate signatures from the sender when they send a signed PDF form in the future.

I have a question related to this - how do you revoke or remove that certification for someone who should no longer have it.  Obviously the file is residing on the computer of the receiver somewhere.  How do you remove it from your computer if, say, the person resigns from the company.  You don't want to have this certificate sitting around since, in essence, it should be null and void because the person isn't there anymore.  How do you get rid of it?  Where is it sitting on the computer?

Thanks.

By adding the certificate (public key) to your "Trusted Identities" you are configuring Acrobat\Reader to recognize and trust signatures created using the corresponding private key (only trhe signer has access to the private key).

As for revoking certificates...

As an end user consuming signed documents, you cannot revoke digital certificates.  Only the issuing Certificate Authority (i.e. VeriSign, or a company's internal certificate server).  If a certificate is revoked, then going forward this status will be reflected in any signatures created using the revoked certificate (private key) whan a signature is validated.  If the certificate is "self-signed", meaning the user created their own digital certificate, then there is no mechanism to revoke the digital certificate.

If you wish to remove the "Trusted Identity" on the client machine, then this is done with Reader bey selecting from the menu Document > Manage Trusted Identities and then selecting and deleting the trused identity.  In Acrobat, the menu option is Advanced > Manage Trusted Identities

Regards

Steve