Jeremy Stein - Journal

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Secret Verifiable Dated Information

I’ve been puzzling over how a person could prove that he had certain information at some date in the past, without publishing it until later. In the movie Quiz Show, one of the contestants sent the answers to himself in registered mail to be able to later prove that the show had been rigged. (This really happened.) That seems like a fairly clever way, assuming the USPS is rigorous in ensuring that the mail is sealed. I wonder whether it would be possible to send an envelope with registered mail and then insert a paper after it was received.

What other way is there to prove that information existed at a certain time in the past? It seems like you’d have to have some trusted authority for dating information. The postmark date is the authority in the above example. How about data encrypted with pgp and cached by The Internet Archive? Any other suggestions?

March 21, 2005 3 Comments.

3 Comments

  1. Benjamin replied:

    if the usps is reliable enough so is any third party that agrees to receiving an envelope on a particular date and holding it for you until requested. You could have someone on the inside at the post office to post date it for you

    March 21st, 2005 at 6:06 pm. Permalink.

  2. Jeremy replied:

    That’s a good point — I hadn’t thought about an insider. However I would be surprised if it would be that easy to turn back the date on the machines.

    Also, I would bet it’s more likely to be a federal offense to forge an old USPS postmark than it would be for, say FedEx or UPS.

    Is there some way to solve this problem using only natural dating? That is, something where the trusted authority is God (nature or physics)?

    March 22nd, 2005 at 9:09 am. Permalink.

  3. Sharon replied:

    You can have your information notorized – dated and signed by any public notary. I have heard of inventors that have had notebooks of ideas notorized and then used this in court to prove that they had the idea first.

    March 31st, 2005 at 9:10 pm. Permalink.

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