Security of Engineering Stamps 1

[firefighter26m]

I have a concern of my engineering stamp being digitally lifted off of drawings and being used on drawings / documents which I have not actually stamped. I thought that throught the use of Adobe and PDF files this would be protected but have come to discover that Adobe Professional allows you to 'touch-up' protected documents, playing around with it I managed to make changes to values within some of the reports.

Does anyone have a solution to this..someway to protect the stamp to prove that I did or did not actually stamp a particular drawing or document?

 

[l3city]

This can happen, but usually you, as an engineer, will sign a contract for say a project. Nowadays, with sharing AutoCad files/plans, almost anybody can "play" the architect or engineer by using other professional stamp/seal. And apparently there is no way to avoid this risk. That is why is important to save and have signed papers/contract with the client in case there are some legal issues involved.
Just my 2-cents, Regards

 

[dpc]

In most states, a "wet" signature is required on at least one set of drawings. These drawings need to be archived basically forever.

As a general rule, whenever we are asked to give a CAD file to a third-party, we remove the digitized engineering stamp from the file. Some engineering firms remove the entire title block.

Giving an electronic file to the client or owner is another issue. We generally include a statement in the transmittal that the drawings can be used for any other work or project.

But there is nothing you can do for total protection. It's no different from someone forging your name on a contract or other legal document. It probably wouldn't take someone long to find your PE # on state board website, find the PE seal design, then create or buy a stamp with your name on it. Other than the fact that it is against the law, of course.

The biggest problem I see is that electronic files with your digitized stamp on it float around and get re-used for another project and no one bothers to remove your seal, giving the false impression that you did the work.

In general, it's a PITA.

 

[zeusfaber]

A *proper* digital signature should be proof against subsequent alteration or transfer to a bogus electronic document.

It works by generating a hash of the document to be signed, then encrypting the hash with the signers (private) signing key. The encrypted hash forms the significant element of the signature.

The signature can be verified by rehashing the document under test, decrypting the signature using the signer's public key, and seeing if the two hashes are the same.

If the document gets altered, the hash generated on verification should (read "will") be different from the original and the verification will fail.

Provided that the private signing key has not been compromised, a forger should be unable to encrypt the hash of his fake document in such a way that it can be decrypted successfully using the alleged originator's public key - and the verification should again fail.

I must admit, I had always thought (without ever having used it for that) that Acrobat did digital signatures properly. One thing to check - once you've touched the drawings up, do the signatures still verify correctly?

A.

 

[dpc]

The determination of whether or not digital signatures are allowed on engineering drawings is up to the engineering boards in each state. It doesn't matter how secure it is, if the state board does not accept it, it is not an allowable method. It is not a technical issue, per se, but a legal one. At this time, we have different requirements and restrictions in nearly every state.

Some states do not even allow signing of reduced sized drawings - they must be full-scale.

When it comes to engineering drawings, the concept of an electronic archive is a myth. You must retain hard copies or microfilm.