Re: IPG Algorith Broken!

Known-plaintext:   Unbreakable, since the pad is never reused
 Chosen-plaintext:  Unbreakable, ditto
 Adaptive-chosen-plaintext: Unbreakable, ditto

Correct but for a different reason. Re-using the pad does render the 
security useless but the other reason is if we know part of the pad 
AND the ciphertext (and hence the plaintext) or part of the plaintext 
and the ciphertext and therefore the pad, We cannot solve the rest of 
the ciphertext as the pad is true random and the next bits are 
independent of all the previous ones so we cannot predict from what 
we have.

A better definition of unbreakable, IMHO, is that there is no way to 
determine the plaintext given unlimited ciphertext and computational 
resources. Sure, this isn`t a complete definition but at least it 
definites perfect security in an analytic sense.



 

  Datacomms Technologies web authoring and data security
       Paul Bradley, Paul@fatmans.demon.co.uk
  Paul@crypto.uk.eu.org, Paul@cryptography.uk.eu.org    
       Http://www.cryptography.home.ml.org/
      Email for PGP public key, ID: 5BBFAEB1
     "Don`t forget to mount a scratch monkey"

On Mon, 25 Nov 1996 paul@fatbrain.demon.co.uk wrote:

> 
>  Known-plaintext:   Unbreakable, since the pad is never reused
>  Chosen-plaintext:  Unbreakable, ditto
>  Adaptive-chosen-plaintext: Unbreakable, ditto
> 
> Correct but for a different reason. 
No correct period, for the same reason. To paraphrase Gertrude Stein, an
OTP is an OTP is an OTP.


>Re-using the pad does render the 
> security useless but the other reason is if we know part of the pad 
> AND the ciphertext (and hence the plaintext) or part of the plaintext 
> and the ciphertext and therefore the pad, We cannot solve the rest of 
> the ciphertext as the pad is true random and the next bits are 
> independent of all the previous ones so we cannot predict from what 
> we have.
> 
More dumbest information, from FAT BRAIN. If an OTP is used more than
once, it is not an OTP by definition. Plaintext xor Plaintext, even in
derivative forms. Like so much of his dribble, that paragraph contains 
some words but I challenge anyone to tell us what it means. It simply
does not say anything which translates into anything meaningful.    


Frequently, you fill in some, and maybe even all of the plaintext, if you
have part of the plain text, for example if you have the partial signature
of a message emanating from the White House of:

       Wi      Jef            on

You might reasonably conclude that the missing characters could be filled
in to be: 
        
       William Jefferson Clinton


Two plaintexts xored together can reveal much more than you might think.

With Kindest regards,

Don Wood

Don Wood <wichita@cyberstation.net> writes:
>
> On Mon, 25 Nov 1996 paul@fatbrain.demon.co.uk wrote:
>
> More dumbest information, from FAT BRAIN. ...

Don, a word of caution. You've been excrutiatingly civil throughout this
discussion, while the cypherpunks have been, well, punks. Paul Bradley's
favorite arguments are to put "(spit)" after your name or to call anything
he can't understand "bullshit". Paul can get away with it, but if you stoop
on their level, then a) you sound more like them, and you don't want to
do that, I'm sure, b) you might get a nastygram from John Gilmore, the
50-ish long-haired bitch who's the "owner" of this "private mailing list".

Caution: John Gilmore is a liar and a content-based censor.

---

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

-----BEGIN PGP SIGNED MESSAGE-----

On Sat, 30 Nov 1996 wichita@cyberstation.net wrote:

> No correct period, for the same reason. To paraphrase Gertrude Stein, an
> OTP is an OTP is an OTP.

And IPGs algorithm is not OTP, so what you're saying is irrelevant.

> More dumbest information, from FAT BRAIN. If an OTP is used more than
> once, it is not an OTP by definition. Plaintext xor Plaintext, even in

Correction.  If I generate a completely random number, and use it in my
pad, and then generate another random number, and the 2 randoms happen to
be the same, they are still perfectly valid pads; as long as the numbers
were truly random.  Don't get me wrong -- its still stupid to use the same
one twice, and it defies the point, but it is not "not an OTP by
definition".

> derivative forms. Like so much of his dribble, that paragraph contains 
> some words but I challenge anyone to tell us what it means. It simply
> does not say anything which translates into anything meaningful.    

Stop describing what you write.

> Frequently, you fill in some, and maybe even all of the plaintext, if you
> have part of the plain text, for example if you have the partial signature
> of a message emanating from the White House of:
> 
>        Wi      Jef            on
> 
> You might reasonably conclude that the missing characters could be filled
> in to be: 
>         
>        William Jefferson Clinton
> 
> 
> Two plaintexts xored together can reveal much more than you might think.
> 

This is, as they say, completely irrelevant.

> Don Wood

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

Unix is the worst operating system; except for all others.
                -- Berry Kercheval


-----BEGIN PGP SIGNATURE-----
Version: 2.6.2

iQEVAwUBMqEjBDCdEh3oIPAVAQFu4Af+NhUpKK24vICvSbV6v5YdQUxGoegwFk8j
S0K0KM3HN7cLnLDPQPWnjtLROkDmh3RBzYZ9DurJmtVX9qC9d95hca4Z+6jyvdJx
oQaUYFil9X7hukQZPU3idsX6XsmXCJXUpB/v+XktfkeqC0Rzp9h1fAVfAu7JNA7b
q/TbCah4yLe4WZORnySds4nTd0hq19niyO6XCesEddL6DEOS2i5rtRe/ATXSmelu
vX16LpvsUIkiyCLMpnPQWBNZbSPOZ9OXDGgj4NNKGP0EFI/eNzwQdNNuBc7dXELk
+g3Dk7F9co0HhqmoDjoX7B3l3MnvozziepfV7KAh5O7cr+iFa7lecQ==
=aeRZ
-----END PGP SIGNATURE-----

On Sun, 1 Dec 1996, The Deviant wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> 
> On Sat, 30 Nov 1996 wichita@cyberstation.net wrote:
> 
> > No correct period, for the same reason. To paraphrase Gertrude Stein, an
> > OTP is an OTP is an OTP.
> 
> And IPGs algorithm is not OTP, so what you're saying is irrelevant.
> 
> > More dumbest information, from FAT BRAIN. If an OTP is used more than
> > once, it is not an OTP by definition. Plaintext xor Plaintext, even in
> 
> Correction.  If I generate a completely random number, and use it in my
> pad, and then generate another random number, and the 2 randoms happen to
> be the same, they are still perfectly valid pads; as long as the numbers
> were truly random.  Don't get me wrong -- its still stupid to use the same
> one twice, and it defies the point, but it is not "not an OTP by
> definition".
>
>
Correction, an OTP means a One Time Pad. If it is used more than once, it
is not a One Time Pad. The likelihood of a duplicate random number series 
of any significant length of course is very remote. If it did occur and 
you were able to  to XOR the resultant ciphertexts together, partial or
complete compromise might be possible. An OTP means one time use period,
why call it a One Time Pad, why not call it a Random Number Series or some
other appellation.

This is just another example or more pendant pap. Obviously, you like
Paul, do not know what you are talking about. You have read some
textbooks and think that makes you are an expert. I suggest that you take
some time off and learn some IT and what an OTP is. It most certainly is
not two identical random number series. 

> 
> > derivative forms. Like so much of his dribble, that paragraph contains 
> > some words but I challenge anyone to tell us what it means. It simply
> > does not say anything which translates into anything meaningful.    
> 
> Stop describing what you write.
> 
> > Frequently, you fill in some, and maybe even all of the plaintext, if you
> > have part of the plain text, for example if you have the partial signature
> > of a message emanating from the White House of:
> > 
> >        Wi      Jef            on
> > 
> > You might reasonably conclude that the missing characters could be filled
> > in to be: 
> >         
> >        William Jefferson Clinton
> > 
> > 
> > Two plaintexts xored together can reveal much more than you might think.
> > 
> 
> This is, as they say, completely irrelevant.
> 

Not nearly as irrelevant as your meaningless dribble.

> > Don Wood
> 
>  --Deviant


With Kindest regards,

Don Wood

wichita@cyberstation.net wrote:
> This is just another example or more pendant pap. Obviously, you like
> Paul, do not know what you are talking about. You have read some
> textbooks and think that makes you are an expert. I suggest that you take
> some time off and learn some IT and what an OTP is. It most certainly is
> not two identical random number series. 

what is IT?

	- Igor.