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From: Frederick Roeber
Sent: Sunday, April 15, 2007 3:05 PM
Subject: Re: On “proving NON copyright infringement” (Re: Dellinger, RISKS-24.61)
Bell Labs used to have a system like this. I read about it a couple decades ago on usenet– (comp.dcom.telecom? sci.crypt?
alt.folklore.computers?) — but I’ve never since been able to dig up much reference to it.
Basically, you’d send it files (or perhaps cryptographic hashes, if you wanted to keep your document secure), and it’d keep a log, and build up a rolling hash. Every week, the resulting hash would be published in a classified ad in the New York Times. (There was an amusing bit about how they had to talk the NYT into accepting the ads; the paper was afraid they were doing something Bad with encrypted
communication.)
If a question ever came up, they’d be able to re-run that week’s hash and compare the results; this would certify the document in question to at least within that week, and if you believed the independence of the other users of the system you could bracket the time much more closely.
Frederick.
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Hmmm, never heard of that.
Reinke Faces Life 