Is this as insecure as it sounds (was FWD: Complete Fax Privacy Draws C

This turned up on alt.anonymous.  One would need a technical specification
or a working model to be sure, but it sounds like home-grown snake oil
to me.  My guess is that a nineteenth-century cryptanalyst could crack
this, and that the TLAs would have a field day.

What do other people think?

> 
>                 Complete Fax Privacy Draws Closer
> 
> 
>      Individuals receiving faxes, be they of a business or
> personal nature, will soon be able to encrypt the contents and
> make them unreadable to people for whom the messages are not
> intended.
>      The new fax encryption technology has been developed by the
> University of Rochester in New York.  The encryption program
> would make all faxes unreadable to the naked eye.  Only by
> placing a customized transparent plastic sheet over the message
> could it be made readable.  Each individual, employee or manager
> would be issued with his own plastic sheet and encryption key
> ensuring messages are only read by those specified in the message
> itself.  The encryption software would not slow the transmission
> and reception of fax messages and the cost of installing the
> system on to existing machines would be minimal.
>      Such software would be indispensable to those whose
> activities require the utmost confidentiality or privacy.  Nosy
> employees, rivals, those providing faxing services and anybody
> else who has, until now, had a birds eye view of your fax
> communications could be successfully abolished from the security
> equation.
>      Though the software has yet to be refined into a marketable
> commodity, it is set to be introduced for public consumption in
> the very near future.
> 
> 
>      Adam Starchild
>      Asset Protection & Becoming Judgement Proof at
>      http://www.catalog.com/corner/taxhaven
> 
> 
-- 
   Alan Bostick             | SWINDON:   What will history say?
Seeking opportunity to      | BURGOYNE:  History, sir, will tell lies as usual.
develop multimedia content. |    George Bernard Shaw, THE DEVIL'S DISCIPLE
Finger abostick@netcom.com for more info and PGP public key

Alan:

On Sun, 31 Dec 1995, Alan L. Bostick wrote:

> This turned up on alt.anonymous.  One would need a technical specification
> or a working model to be sure, but it sounds like home-grown snake oil

	Sounds like snake oil to me.

> >                 Complete Fax Privacy Draws Closer
> > personal nature, will soon be able to encrypt the contents and
> > make them unreadable to people for whom the messages are not

	PGP & a fax modem & a good OCR provides this.

	Or PGP the message and either e-mail or telex it.
	
> > placing a customized transparent plastic sheet over the message
> > could it be made readable.  Each individual, employee or manager
> > would be issued with his own plastic sheet and encryption key

	A plastic sheet is going to let me read it, and nobody 
	else?  I guess that would work, if one was using ---
	I forgotten what it was called, where you cut a number
	of squares on a sheet of cardboard, put over a sheet
	of paper, write the characters in the spaces, then
	lift the sheet, and write garbage to fill up the rest
	of the sheet, so that nobody else can see what the 
	characters were.  I think I was in kindergarten when 
	we did that, untill we discovered that our teacher
	could read our "secret" messages, without the cardboard
	sheet.  << The handwriting of the real message differed
	from that of the garbage words. >>

> >      Though the software has yet to be refined into a marketable
> > commodity, it is set to be introduced for public consumption in
> > the very near future.
	
	Is this the same as Jerry Pournelle "real soon now'?

	I think I'll stick to using PGP and sending e-mail.

        xan

        jonathon
        grafolog@netcom.com



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If the plastic sheet is just a fixed mask, then this scheme yields 
instantly to chosen  plain-text (just send an all-black page), really 
quickly to known-plaintext, and pretty quickly to multiple cyphertexts.

There's got to be more to it than that

Simon

(defun modexpt (x y n)  "computes (x^y) mod n"
  (cond ((= y 0) 1) 	((= y 1) (mod x n))
	((evenp y) (mod (expt (modexpt x (/ y 2) n) 2) n))
	(t (mod (* x (modexpt x (1- y) n)) n))))