Hi Martin,

>Between these two events I had a back-up drive go belly up on me and a lot of the files were heavily corrupted and >could not be salvaged from the drive, my model was among those files. I duly went and downloaded my work files >back from GrabCAD, but since it's a copy of a copy that's gone from one drive to another as a "new file" the dates and >times those files were created are all different from when i created the model, thus technically speaking, I can't prove >when I created the file any more leaving me wide open for someone else to claim its copyright based on date. I don't >mind in this case as I shared my file freely and I suppose one could say it's my own fault for sharing it. But it has >highlighted this issue to me should I produce something I might not want to freely share in the future.

Maybe you could do this to claim your ownership... Simply use the freely available GNU Privacy Guard (gpg), or the famous PGP, which is global email encryption standard since the early 90's, and create a detached digital signature for your .3dm file. This procedure would not touch your 3dm file and in case you lost your original and download an unmodified ver. of your file, the signature would be still valid... The signature contains your Public Key ID, Name, email address and the creation date/time, when a file was signed. So if you sign your .3dm files with a detached signature and put also the signature in a zip file along your model, this should prove hopefully your ownership. PGP/gpg engryption is secure.

As test i attach a simple .3dm file (a sphere) and a detached signature file, which can be verified by other gpg/PGP users.

(P.S. you can upload your Public gpg Key on public key servers:

https://keyserver2.pgp.com/vkd/GetWelcomeScreen.event

http://sks-keyservers.net/i/

and friends, workmates etc. can verify your sig for example. (my key id is 0x560007F8))


Best regards
Stefan