[41424] in Cypherpunks
Re: responce to graphic encryption replies
daemon@ATHENA.MIT.EDU (Ron McCoy)
Fri Oct 13 17:55:23 1995
Errors-To: cpadmin@toad.com
From: Ron McCoy <rmccoy@mercury.interpath.net.interpath.com>
To: cypherpunks@toad.com
Date: Fri, 13 Oct 1995 11:34:59 -0400 (EDT)
In-Reply-To: <199510130432.AAA14986@thor.cs.umass.edu> from "Futplex" at Oct 13, 95 00:32:51 am
>
> Steve Orrin writes:
> [...]
> > One of the key strengths, as I see it, of graphic encryption is
> > that during decryption via hacking, there is an added time element when
> > a human interface is required to verify the product, ( since it is a
> > graphic picture being produced, regular checksums for intelligible
> > words can't be used sans implementing OCR), even if this is only 10
> > milliseconds per try this is increases the time to crack
>
> This is an interesting point I hadn't previously considered. Can anyone
> comment on the state of the art in fast approximate character recognition ?
> I expect that the people working on recognition of text in TV pictures etc.
> would have a good idea.
>
[....]
>
> -Futplex <futplex@pseudonym.com>
>
I wouldn't think you would have to use OCR to detect a successful
decryption. The graphic file is going to have a highly correlated
structure, long runs of white space etc. The statistics for such a file
would be different than the random distribution you'd get from using the
wrong key. Even if the graphics format is compressed, leading to a more
even distribution, there might be known plaintext at the beginning of the
file, headers, size etc.
Ron McCoy
Rmccoy@mercury.interpath.net
