[news.admin] Forgeries

caasnsr@nmtsun.nmt.edu (Clifford Adams) (02/09/88)

In article <8802080327.AA02920@jiff> gsmith@brahms.BERKELEY.EDU () writes:
>
> If anyone feels strongly enough about protection against
>forgeries, one system which does not involve any fixes by anyone
>but the user himself is to post a large number which is the
>product of two large enough (say, ~10^30) primes or pseudoprimes.

	A very good try.  But this method can have a vicious flaw.
What if the forger is the first one to post the number?  He can then
claim that the real user is the one posting all the forgeries.  And he
will have proof, if others believe in the method.

>   ucbvax!brahms!gsmith    Gene Ward Smith/Brahms Gang/Berkeley CA 94720

	Please send replies by mail, as I don't often read this
newsgroup.

-- 
 Clifford Adams  ---  " I understand only inasmuch as I become... "
 ...{cmcl2, ihnp4}!lanl!unm-la!unmvax!nmtsun!caasnsr
 ...gemini!crunch!unmvax!nmtsun!caasnsr

greg@phoenix.Princeton.EDU (Gregory Nowak) (02/10/88)

In article <1368@nmtsun.nmt.edu> caasnsr@nmtsun.nmt.edu (Clifford Adams) writes:
>In article <8802080327.AA02920@jiff> gsmith@brahms.BERKELEY.EDU () writes:

>> If anyone feels strongly enough about protection against
>>forgeries, one system which does not involve any fixes by anyone
>>but the user himself is to post a large number which is the
>>product of two large enough (say, ~10^30) primes or pseudoprimes.

>	A very good try.  But this method can have a vicious flaw.

A PERFECT try. It has no vicious flaw.

>What if the forger is the first one to post the number?  He can then
>claim that the real user is the one posting all the forgeries.  And he
>will have proof, if others believe in the method.

Read my lips, you innumerate slob: He uses a DIFFERENT composite
number for EACH posting. There are LOTS of 25-35 digit primes -- I
sincerely doubt that even Gene Ward Smith will run out of pairs of
primes no matter HOW many hours a day he spends posting articles.  One
could even set up a probgram to include a hefty prime AUTOMATICALLY in
each posting. Then if you decide to doubt Gene's posting the assertion
that shit stinks, you SAY SO in a posting on the net, or email Gene --
hwereupon he sends the FACTORS of the number which is uniquely
associated with the article you were worried about. The system works
because it takes TOO LONG to factor 70 digit primes -- not even a
forger could get the job done.

Does EVERYONE understand how this works now?

Kudos to Gene for reminding the net of one of the uses of math.


-- 
...!seismo!princeton!phoenix!greg


                                 Greg Nowak/Phoenix Gang/Princeton NJ 08540

matt@oddjob.UChicago.EDU (Stop calling me Fred) (02/11/88)

) >gsmith@brahms.BERKELEY.EDU () writes:
) >>... post a large number which is the
) >>product of two large enough (say, ~10^30) primes or pseudoprimes.

) caasnsr@nmtsun.nmt.edu (Clifford Adams) writes:
) >	A very good try.  But this method can have a vicious flaw.

greg@phoenix.Princeton.EDU (Gregory Nowak) writes:
) A PERFECT try. It has no vicious flaw.

Gods, what a simpleton!

) Read my lips, you innumerate slob: He uses a DIFFERENT composite
) number for EACH posting. ... if you decide to doubt Gene's posting
) the assertion that shit stinks, you ... email Gene --
) hwereupon he sends the FACTORS of the number which is uniquely
) associated with the article you were worried about.

Suppose somebody reuses Gene's own numbers?  Which article is the
true one?  Whichever one Gene says is real?  Then how is this in any
way better than just ASKING THE PURPORTED AUTHOR BY EMAIL whether an
article is "genuine"?  It isn't.

) Does EVERYONE understand how this works now?

Yes, everyone except Greg Nowak.

) Kudos to Gene for reminding the net of one of the uses of math.

And to Greg for showing how blind, kneejerk applications of
mathematics can lead to a false sense of security or power.

				Matt Crawford

greg@phoenix.Princeton.EDU (Gregory Nowak) (02/11/88)

In article <14347@oddjob.UChicago.EDU> matt@oddjob.UChicago.EDU (Stop calling me Fred) writes:
>) >gsmith@brahms.BERKELEY.EDU () writes:
>) >>... post a large number which is the
>) >>product of two large enough (say, ~10^30) primes or pseudoprimes.

>) caasnsr@nmtsun.nmt.edu (Clifford Adams) writes:
>) >	A very good try.  But this method can have a vicious flaw.

>greg@phoenix.Princeton.EDU (Gregory Nowak) writes:
>) A PERFECT try. It has no vicious flaw.

>Gods, what a simpleton!

What an asshole!

>Suppose somebody reuses Gene's own numbers?  Which article is the
>true one?  Whichever one Gene says is real?  Then how is this in any
>way better than just ASKING THE PURPORTED AUTHOR BY EMAIL whether an
>article is "genuine"?  It isn't.

Gene uses different numbers for each article. Then if there's a
duplicate, he who can supply the factors gets to call the shots as to
which article is genuine. I suppose that all this is beyond you. You
probably think that if you just keep working HARD ENOUGH, you'll
FINALLY be able to trisect the angle, and all those snobby
mathematicians who have been pretending to know the truth will get
their comeuppance. IF you believe the forger can receive Gene's mail
AND forge outgoing mail under Gene's name, THEN there would be no
security to merely asking the purported autor by email which articles
are genuine. But you are ignoring completely the trapdoor function of
the primes: If Gene 1) uses a different composite for each article 2)
offers to authenticate by mail, and 3) does not keep files of his
primes, but only hardcopy that he carries around with him, he's safe.

>) Does EVERYONE understand how this works now?

Evidently, everyone except Matt Crawford.

>) Kudos to Gene for reminding the net of one of the uses of math.

>And to Greg for showing how blind, kneejerk applications of
>mathematics can lead to a false sense of security or power.

Power? Who's talking about power? Only Matt Crawford, who evidently is
afraid enough of mathematics, for god only knows what reason, to bitch
about its uses. What is "blind" and "kneejerk" about it? I suppose to
use the method you have to know what primes are and what
multiplication is, so it seems mysterious to you, and the fact that
it's a relatively simple method that works is galling to you (hence
"kneejerk"?), but that's something you're just going to have to live
with while the world goes along merrily without you. What is the basis
for your irrational fear of mathematics? Did you get your prick caught
in a sliderule once?

Learn to count.


-- 
...!seismo!princeton!phoenix!greg


                                 Greg Nowak/Phoenix Gang/Princeton NJ 08540

") (02/12/88)

Apologies to news.admin which must no longer be intested in this.
I will now resubscribe to alt.flame.  If Greg cares (or dares) to
reply there, I will answer there.  If he responds in news.admin I
will consider that he has implicitly given up and that the subject
is closed.

) matt@oddjob.UChicago.EDU (That's me) writes about Greg Nowak:
) >Gods, what a simpleton!

To which greg@phoenix.Princeton.EDU (Gregory Nowak) artfully responds:
) What an asshole!

Well, at least he didn't change the subject.

But back to the topic:
) >Suppose somebody reuses Gene's own numbers?  Which article is the
) >true one?  Whichever one Gene says is real?  Then how is this in any
) >way better than just ASKING THE PURPORTED AUTHOR BY EMAIL whether an
) >article is "genuine"?  It isn't.

) Gene uses different numbers for each article. Then if there's a
) duplicate, he who can supply the factors gets to call the shots as to
) which article is genuine.

You keep changing your method, Greg.  You can't have it all ways at
once.  Last time around you had J. Random Reader asking Gene for the
factors of a number in order to know that an article was valid.  But
the number might have been seen in a forged article.  Now you say
whoever knows the factorization gets to declare what articles are
real, so a forger just has to put in a number whose factorization he
knows, and then say "that was a Gene Smith article".  Sounds stupid?
It is, but that's what you said.

Here comes a shock for you Greg: I know about secure digital
signature systems.  It seems that you don't, because you keep
describing weak, half-assed attempts at one.

) IF you believe the forger can receive Gene's mail AND forge
) outgoing mail under Gene's name, THEN there would be no security to
) merely asking the purported autor by email which articles are
) genuine.

Are you saying that YOU believe the above hypothesis, or that I do?
If the latter, show your evidence.

) But you are ignoring completely the trapdoor function of
) the primes: If Gene 1) uses a different composite for each article 2)
) offers to authenticate by mail, and 3) does not keep files of his
) primes, but only hardcopy that he carries around with him, he's safe.

Oh, crap.  Suppose someone requests authentication and then posts a
back-dated forgery?  Want to ammend your statement again, Greg?

) >And to Greg for showing how blind, kneejerk applications of
) >mathematics can lead to a false sense of security or power.

) Power? Who's talking about power? Only Matt Crawford, who evidently is
) afraid enough of mathematics, for god only knows what reason, to bitch
) about its uses. What is "blind" and "kneejerk" about it? 

Kneejerk is you when you see an article with arithmetic in it and you
say "Oh, hey, higher math!  Hooray for math!" without giving a
pickled neuron's worth of thought to the application itself.

)  What is the basis for your irrational fear of mathematics?

Bring it up again in alt.flame and we'll compare degrees, little boy.

				Matt Crawford

faustus@ic.Berkeley.EDU (Wayne A. Christopher) (02/12/88)

Giving the primes that go with the previous article won't work.  Say
Gene posts such an article, and Joe Forger in Berkeley reads it 10 minutes
after it's posted.  Then he forges an article from a different
system, with timestamps that indicate it was written BEFORE Gene's,
but with the same primes in it.  Since network delays are unpredictable
there's no way to tell which is the real article.

You can't win...

	Wayne