Re: IPG Algorith Broken!

At  4:21 PM 11/23/96 -0800, John Anonymous MacDonald wrote:
>At 12:33 PM 11/23/1996, Eric Murray wrote:
>>You point could have been that the same problem exists
>>for proofs- that next week someone could come up
>>with a way to prove, for all time, that an algorithim
>>really IS unbreakable.  So, to cover that posibility
>>I should have said "it's currently impossible to
>>prove an algorithim unbreakable". :-)
>
>Or, more accurately, nobody credible has seen such a proof.  But, a
>clever person might invent one.

I thought Shannon proved one-time-pads to be unbreakable using information
theory.


-------------------------------------------------------------------------
Bill Frantz       | The lottery is a tax on    | Periwinkle -- Consulting
(408)356-8506     | those who can't do math.   | 16345 Englewood Ave.
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On Sat, 23 Nov 1996, Bill Frantz wrote:

> >>I should have said "it's currently impossible to
> >>prove an algorithim unbreakable". :-)
> >
> >Or, more accurately, nobody credible has seen such a proof.  But, a
> >clever person might invent one.
> 
> I thought Shannon proved one-time-pads to be unbreakable using information
> theory.
> 
Shannon did, but Paul Bradley and friends(sic) proved that he/they could
brute force OTPs, its on the record, so I guess Shannon was wrong, Nes
pas?  Someone as certain of his facts as PB cannot possibly be wrong, or
did he say he was asleep - I guess so, he is obviously always asleep.

I also can prove that our algorithm cannot be broken. All you
have to do is to examine the algorithm and you will understand why it is
unbreakable. That is a lot of chutzpah, but once you understand the
algorithm and how simple it is to prove its unbreakability, then you will
understand that our claim is absolutely correct.

Unfortunately, many of you would rather beat your fingers on the
keyboard about the abstract than find out the truth for yourself. It
is really very simple. Again, I repeat, if you would like a free copy,
please send a e-mail request to:

                     ipsales@cyberstation.net

As for the algorithm, it is at:

                     netprivacy.com



With kindest regards, 

Don Wood

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On Sat, 23 Nov 1996, Bill Frantz wrote:

> At  4:21 PM 11/23/96 -0800, John Anonymous MacDonald wrote:
> >At 12:33 PM 11/23/1996, Eric Murray wrote:
> >>You point could have been that the same problem exists
> >>for proofs- that next week someone could come up
> >>with a way to prove, for all time, that an algorithim
> >>really IS unbreakable.  So, to cover that posibility
> >>I should have said "it's currently impossible to
> >>prove an algorithim unbreakable". :-)
> >
> >Or, more accurately, nobody credible has seen such a proof.  But, a
> >clever person might invent one.
> 
> I thought Shannon proved one-time-pads to be unbreakable using information
> theory.

Different ball game.  OTP isn't "unbreakable" .  OTPs are secure because
no matter what key you use, it _will_ decrypt, so your plaintext is still
hidden simply because it could decrypt to whatever the person trying to
decrypt it wants it to.  Its not that its unbreakable, its that its
breakable in _so many ways_.  

 --Deviant
   PGP KeyID = E820F015 Fingerprint = 3D6AAB628E3DFAA9 F7D35736ABC56D39

Do, or do not; there is no try.
		-- Yoda


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On Sun, 24 Nov 1996, The Deviant wrote:

> > At  4:21 PM 11/23/96 -0800, John Anonymous MacDonald wrote:
> > >At 12:33 PM 11/23/1996, Eric Murray wrote:
> > >>You point could have been that the same problem exists
> > >>for proofs- that next week someone could come up
> > >>with a way to prove, for all time, that an algorithim
> > >>really IS unbreakable.  So, to cover that posibility
> > >>I should have said "it's currently impossible to
> > >>prove an algorithim unbreakable". :-)
> > >
> > >Or, more accurately, nobody credible has seen such a proof.  But, a
> > >clever person might invent one.
> > 
> > I thought Shannon proved one-time-pads to be unbreakable using information
> > theory.
> 
> Different ball game.  OTP isn't "unbreakable" .  OTPs are secure because
> no matter what key you use, it _will_ decrypt, so your plaintext is still
> hidden simply because it could decrypt to whatever the person trying to
> decrypt it wants it to.  Its not that its unbreakable, its that its
> breakable in _so many ways_.  
> 

More nonsense - unbreakable means that you cannot determine what the
plaintext is. Shannon proved that you cannot prove what the plaintext
is for OTPs, or for the system we have developed either. The fact that it
could possibly be any plain text simply is another way of saying that it
is unbreakable, they are one and the same thing. Like so many you are
talking in circles and do not know what you are talking about or you
would not waste your time on such nonsense - Paul Bradley even knows how
to brute force OTPs, so you must be wrong there to.

With Kindest regards,

Don Wood
 

> 
>

Don Wood <wichita@cyberstation.net> writes:
> > Different ball game.  OTP isn't "unbreakable" .  OTPs are secure because
> > no matter what key you use, it _will_ decrypt, so your plaintext is still
> > hidden simply because it could decrypt to whatever the person trying to
> > decrypt it wants it to.  Its not that its unbreakable, its that its
> > breakable in _so many ways_.
>
> More nonsense - unbreakable means that you cannot determine what the
> plaintext is. Shannon proved that you cannot prove what the plaintext
> is for OTPs, or for the system we have developed either. The fact that it
> could possibly be any plain text simply is another way of saying that it
> is unbreakable, they are one and the same thing. Like so many you are
> talking in circles and do not know what you are talking about or you
> would not waste your time on such nonsense - Paul Bradley even knows how
> to brute force OTPs, so you must be wrong there to.

That's precisely right - (almost all) cypherpunks have no idea what they're
talking about. They use "kewl" words without understanding what they mean.
The recent discussion of whether the (allegedly gay) droid Data used PGP
or "fractal encryption" in some scifi movie is a good example.

Some of these bullies, like Paul Bradley, realize that they don't know
the meanings of the words they use. Paul Bradley not only posts nonsense
about brute force attacks on OTP, but also harrasses anyone who exposes
his utter ignorance, in en effort to intimidate them into shutting up.

"Cypherpunks'" opinion of any proposed new cryptosystem is worthless and
irrelevant.

---

Dr.Dimitri Vulis KOTM
Brighton Beach Boardwalk BBS, Forest Hills, N.Y.: +1-718-261-2013, 14.4Kbps

From: wichita@cyberstation.net
   Date: Sat, 30 Nov 1996 02:41:28 -0600 (CST)
   cc: Bill Frantz <frantz@netcom.com>,
	   John Anonymous MacDonald <nobody@cypherpunks.ca>, cypherpunks@toad.com
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

   Shannon proved that you cannot prove what the plaintext
   is for OTPs,


Let P, K, and C represent bit strings of equal length.  Given a
ciphertext C, for every plaintext P there exists a key K such that

  P XOR K = C.

This is true (K=P XOR C).


   or for the system we have developed either.

False.

Let P and C represent byte strings of equal (arbitrary) length and K
represent the key string of fixed length.

The IPG algorithm can be summarized

  C = P XOR PRNG(K)

where PRNG(K) is the output of the pseudo-random number generator with
seed K.  The details of the PRNG are unimportant for this argument.

For every ciphertext C longer than K, there exists a plaintext P such that
no K will satisfy

  C = P XOR PRNG(K).

Proof: There are 256^length(K) possible keys (roughly 10^34322).
There are therefore at most this many possible decryotions of the
given plaintext.  Since length(C) > length(K), there are more possible
plaintexts than possible decryptions.

Shannon's proof of the security of the OTP therefore doesn't
apply to IPG's cipher.

Assume that the PRNG is resistant to analysis. Given the size of the
keyspace, it is not feasible to search the whole keyspace hoping
something like a plaintext pops out.  However, it is easy to take a
key obtained through some other means and verify that the plaintext
makes sense.  Since the PRNG is assumed resistant to analysis, this
constitutes proof that the plaintext is correct (since it's infeasible
to find a key that decrypts the ciphertext to another plausible
plaintext).

Of course, all encryption algorithms short of the OTP allow an
attacker to prove a key correct, but most cryptographers don't claim
their algorithms to be as secure as OTPs.