Cryptography-Digest Digest #634, Volume #13 Mon, 5 Feb 01 17:13:01 EST
Contents:
Re: OverWrite freeware completely removes unwanted files from hard drive ("Tor
Rustad")
Re: DH question (DJohn37050)
Re: OverWrite freeware completely removes unwanted files from hard drive (Richard
Heathfield)
SHA-256 in Java ("Marcin")
Re: Most secure code for US Citizen. ("Jeffrey A. Six")
Re: Do you like playing with numbers? (Daniel)
Re: Phillipine math guy claims to have fast RSA Factoring... (John Savard)
Re: Encrypting Predictable Files (SCOTT19U.ZIP_GUY)
Re: Phillipine math guy claims to have fast RSA Factoring... ([EMAIL PROTECTED])
Re: On combining permutations and substitutions in encryption (Bryan Olson)
Re: Article (John Savard)
Re: Tree algorithm ("Brian McKeever")
Re: Encrypting Predictable Files ("Joseph Ashwood")
Re: Rijndael's resistance to known plaintext attack ("Joseph Ashwood")
Re: TSEPRNG, a secure RNG ? (Tim Tyler)
Re: DH question (Bryan Olson)
Re: Where is the encryption hardware? (Tim Tyler)
Re: OverWrite freeware completely removes unwanted files from hard drive (Daniel)
Re: Phillipine math guy claims to have fast RSA Factoring... (Padgett 0sirius)
Re: Most secure code for US Citizen. (Simon Johnson)
Re: Advice needed ("Joseph Ashwood")
----------------------------------------------------------------------------
From: "Tor Rustad" <[EMAIL PROTECTED]>
Subject: Re: OverWrite freeware completely removes unwanted files from hard drive
Date: Mon, 5 Feb 2001 20:32:39 +0100
"Richard Heathfield" <[EMAIL PROTECTED]> wrote in message
> Anthony Stephen Szopa wrote:
> >
> > OverWrite freeware completely removes unwanted files from hard drive
>
> I tried it and it didn't work. I got this error:
>
> ./OvrWrite.exe: Permission denied
>
> I would have gone looking for the problem in the source code, only you
> don't provide any.
Next time Richard, never download and run programs you don't trust. From
disassembling the program you might discover that this was a trojan horse.
<moderate flame snipped>
> > State-of-the-art detection technology and
> > the subtleties of hard drive technology have made most overwritten
> > and deleted data on magnetic media recoverable. Simply overwriting
> > a file a few times is just not good enough.
>
> Right. But it's better than running "security" software blind.
Exactly. BTW, the real problem with a "secure delete", is not overwriting
multiple times, but overwriting all relevant places.
--
Tor <torust AT online DOT no>
------------------------------
From: [EMAIL PROTECTED] (DJohn37050)
Date: 05 Feb 2001 19:54:35 GMT
Subject: Re: DH question
needs to be an abelian group to do DH as normally concieved.
Don Johnson
------------------------------
Date: Mon, 05 Feb 2001 21:15:14 +0000
From: Richard Heathfield <[EMAIL PROTECTED]>
Subject: Re: OverWrite freeware completely removes unwanted files from hard drive
Tor Rustad wrote:
>
> "Richard Heathfield" <[EMAIL PROTECTED]> wrote in message
> > Anthony Stephen Szopa wrote:
> > >
> > > OverWrite freeware completely removes unwanted files from hard drive
> >
> > I tried it and it didn't work. I got this error:
> >
> > ./OvrWrite.exe: Permission denied
> >
> > I would have gone looking for the problem in the source code, only you
> > don't provide any.
>
> Next time Richard, never download and run programs you don't trust. From
> disassembling the program you might discover that this was a trojan horse.
$ hexdump OvrWrite.exe | head
0000000 5a4d 0050 0002 0000 0004 000f ffff 0000
0000010 00b8 0000 0000 0000 0040 001a 0000 0000
0000020 0000 0000 0000 0000 0000 0000 0000 0000
0000030 0000 0000 0000 0000 0000 0000 0200 0000
0000040 10ba 0e00 b41f cd09 b821 4c01 21cd 9090
0000050 6854 7369 7020 6f72 7267 6d61 6d20 7375
0000060 2074 6562 7220 6e75 7520 646e 7265 5720
0000070 6e69 3233 0a0d 3724 0000 0000 0000 0000
0000080 0000 0000 0000 0000 0000 0000 0000 0000
I think this is proof positive that Mr Szopa's binary is not capable of
running under Linux.
Source code, Mr Szopa! Source code!
--
Richard Heathfield
"Usenet is a strange place." - Dennis M Ritchie, 29 July 1999.
C FAQ: http://www.eskimo.com/~scs/C-faq/top.html
K&R Answers: http://users.powernet.co.uk/eton/kandr2/index.html
------------------------------
From: "Marcin" <[EMAIL PROTECTED]>
Subject: SHA-256 in Java
Date: Mon, 5 Feb 2001 15:26:20 -0800
I couldn't find a Java implementation of SHA-256 so I made my own. I'm
sharing it with this fine community at:
http://www.optymalni.com/~marcin/
------------------------------
From: "Jeffrey A. Six" <[EMAIL PROTECTED]>
Subject: Re: Most secure code for US Citizen.
Date: Mon, 5 Feb 2001 15:30:30 -0500
actually, as long as you stay up-to-date with hotfixes, you fix the
vulnerabilities. Microsoft might have alot of vulnerabilities in their
products, but when one comes to their attention, a fix is out in a week at
the most. As an aside, upgrading NT to 2000 fixes a large number of
vulnerabilites, and the use of Windows Update in 2000 to apply
hotfixes/service packs is a nice way of staying up-to-date. Downloading the
update which checks for updates automatically keeps you very current and
allows your system to stay immune for vulnerabilites as they come out.
As an aside, newly discovered Unix/Linux vulnerabilities come out every
couple of weeks to. Singling out MS products is not fair or accurate. But,
this is not the time or place for this, so I digress.
-j6
=====================================================================
Jeffrey A. Six
University of Delaware [EMAIL PROTECTED]
Computer & Information Sciences http://www.cis.udel.edu/~six
Electrical & Computer Engineering
"We have a little saying around here . . .
'Let Michigan handle it.'"
"Roger Schlafly" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]...
> Michael Robbins wrote:
> > I use win-NT. What vulnerabilities exist?
>
> Newly discovered Win-NT vulnerabilities have been announced every
> couple of weeks or so, and that has gone on for years. You have
> no hope of even listing all the problems, much less fixing them.
------------------------------
From: [EMAIL PROTECTED] (Daniel)
Subject: Re: Do you like playing with numbers?
Date: Mon, 05 Feb 2001 21:12:59 GMT
On Mon, 05 Feb 2001 14:09:02 GMT, Bob Silverman <[EMAIL PROTECTED]>
wrote:
> cryptography does not depend upon algorithm secrecy. It
>depends on key secrecy.
>
Suppose you would have a very good algorithm (like Rijndael or TwoFish
or ..) but keep that and the keys a secet, would that be a nightmare
for the (enemy) cryptoanalysts or would it just mean that you've
bought some extra time for your own system ? An extra dimension is
added if the algorithm is not known (cf Painvin and Nebel). I suppose
that lots of things fall/rise on how one "exploits" this extra
dimension. Just an idea, though...
best regards,
Daniel
------------------------------
From: [EMAIL PROTECTED] (John Savard)
Subject: Re: Phillipine math guy claims to have fast RSA Factoring...
Date: Mon, 05 Feb 2001 21:09:47 GMT
On Mon, 05 Feb 2001 18:43:37 GMT, "arcmight" <[EMAIL PROTECTED]>
wrote, in part:
>http://www.mb.com.ph/INFO/2001-02/IT020601.asp
The first article I saw on this was ambiguous. It could have been that
he found formulas that simply permitted more efficient _decoding_ of
RSA, and not a crack at all.
John Savard
http://home.ecn.ab.ca/~jsavard/crypto.htm
------------------------------
From: [EMAIL PROTECTED] (SCOTT19U.ZIP_GUY)
Subject: Re: Encrypting Predictable Files
Date: 5 Feb 2001 21:12:06 GMT
[EMAIL PROTECTED] (Splaat23) wrote in <95mq63$6q0$[EMAIL PROTECTED]>:
>Umm, I must be missing something, but don't all block ciphers support
>this "feature". I mean, a block cipher defines a key-base bijective
>permutation. That permutation can be just as secure one way as it is
>the other. I just used RC6 and Rijndael, and they both worked in this
>respect: decrypt data with a key and you get gibberish (ciphertext?),
>then encrypt it with the same key to get the data back. If this is what
>you want, any file encrypting utility can be adapted to do this, but
>I'm not entirely sure this is that useful.
>
You used specail mods and special length files. Try to decrpt ascii
text that is 11 bytes long as an example. See if it encrypts back to
the original file. As far as I know only the Rijndael as used in
Matss BICOM has this feature.
David A. Scott
--
SCOTT19U.ZIP NOW AVAILABLE WORLD WIDE
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Scott famous encryption website **now all allowed**
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Scott LATEST UPDATED source for scott*u.zip
http://radiusnet.net/crypto/ then look for
sub directory scott after pressing CRYPTO
Scott famous Compression Page
http://members.xoom.com/ecil/compress.htm
**NOTE EMAIL address is for SPAMERS***
I leave you with this final thought from President Bill Clinton:
------------------------------
From: [EMAIL PROTECTED]
Subject: Re: Phillipine math guy claims to have fast RSA Factoring...
Date: Mon, 05 Feb 2001 21:16:29 GMT
The phillipino guy is right.
1. We can solve for x in 2^x = 1 mod n for any n
2. With a little modification, we can find x such that a^x = 1 mod n for
any a and n (First write a in binary. Then solve for n*y=2^x-a just like
how he solves for n*y=2^x-1)
3. Now we can find (or guess probabilistically) m such that a^m = 1 mod
n for all a.
3. Then p = gcd(n, a^(x/2)-1) for half of all the a's.
uk oh RSA cracked.
What's gonna happen to business on internet now?
Sent via Deja.com
http://www.deja.com/
------------------------------
From: Bryan Olson <[EMAIL PROTECTED]>
Subject: Re: On combining permutations and substitutions in encryption
Date: Mon, 05 Feb 2001 21:25:09 GMT
Benjamin Goldberg wrote:
> David Wagner wrote:
[...]
> > To be more precise, you need to give me
> > a family of ciphers {C_k}, one for each value of k. Think of
> > k as a security parameter: The running time of C_k must be
> > polynomial in k, whereas the security condition is that
> > breaking C_k should be super-polynomial in k.
> > If there exists a family of ciphers where these two conditions
> > are met, then P != NP.
>
> What if k is the number of bits in the key? Are you saying
> that if P=NP, then a system which enciphers with a k bit key
> must either take superpolynomial time (in terms of k) to encrypt
> or else take polynomial time (in terms of k) to break?
>
> Somehow, I doubt that.
Well, it's certainly not an obvious result.
> Let's suppose that we have an encryption system with a size
> k key, and unicity distance u. Further suppose that we have
> a way of converting a plaintext/ciphertext pair into a 3SAT
> problem -- and that we have u pairs.
>
> I'm sure you'll agree that if P!=NP, then it takes
> superpolynomial time (with respect to the number of 3SAT
> terms) to solve this 3SAT problem,
No. If P!=NP then the worst case of 3SAT is super-polynomial.
That does not imply the subset of 3SAT produced by reduction
from the cipher input/output will be super-polynomial.
> and if P=NP, then it takes polynomial time.
Right.
> Furthermore, our conversion algorithm might be made to take
> polynomial time (with respect to the number of 3SAT terms)
[...]
> But there's one [big] problem with all this. How many terms are
> in the 3SAT problem? If the number of terms is superpolynomial
> wrt k
The reduction time is polynomial in the size of input.
--Bryan
Sent via Deja.com
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------------------------------
From: [EMAIL PROTECTED] (John Savard)
Subject: Re: Article
Date: Mon, 05 Feb 2001 21:18:56 GMT
On Fri, 2 Feb 2001 22:13:04 -0600, "Carpe Diem" <[EMAIL PROTECTED]>
wrote, in part:
>You are right. Probably I began reading with a little bit of prejudice and I
>misunderstood.
I'm not so sure now. In another post, an article is quoted where the
mathematician demonstrates that he has found a fast algorithm for
finding modular reciprocals.
And he does seem to have the idea that this cracks RSA, although he
appears to have missed the part about not knowing what number to
calculate the reciprocal modulo!
I think the algorithm in question, however, is well-known and
standard:
finding the reciprocal of an odd binary number, modulo 2^n:
let A, B, and C be unsigned n-bit storage areas
set A=number
set B=number
set C=1
set D=1
do the following until A=0
- shift A left one place
- shift D left one place
- if the bitwise AND of B and D is not zero:
-- XOR A with B, placing the result in B
-- add D to C, placing the result in C
So far, I'm not impressed. Maybe further details will change my mind;
I've always been nervous about the *possibility* that there might be a
fast way to break public-key systems.
John Savard
http://home.ecn.ab.ca/~jsavard/crypto.htm
------------------------------
From: "Brian McKeever" <[EMAIL PROTECTED]>
Subject: Re: Tree algorithm
Date: Mon, 5 Feb 2001 13:35:01 -0800
"Ned Scholes" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]...
> I'm interested in an algorithm which search through a tree for a special
> value and then returns the "cheepest" way there.
The algorithm to use is to split the tree into two sets, S and ~S.
Initially, S contains just the start vertex, and ~S contains everything
else. At each step, you find the edge with lowest cost that has a vertex in
each of S and ~S, and move the vertex to in ~S to S. Eventually (assuming
the graph is finite and connected), the target vertex will be brought into
S, and if you consider just the edges used to add vertices (which form a
tree), you have a unique path which is the lowest cost path from start to
finish.
Proof is left to the reader.
Brian
------------------------------
From: "Joseph Ashwood" <[EMAIL PROTECTED]>
Subject: Re: Encrypting Predictable Files
Date: Mon, 5 Feb 2001 13:11:39 -0800
Just to try to cut down on the confusion, you've apparently attracted the
attention of DS (don't worry we've all made that mistake, some of us several
times). There are several possibilities. First and foremost, since you said
large portions of your file are predictable I would recommend against RC4.
What I suggest instead is to use a strong block cipher (Rijndael would be a
very good one, http://csrc.nist.gov/encryption/aes/). And that you use a
strong cipher mode. The idea given by Don Johnson (with additional
commentary by Dido Sevilla) is a good one, and probably the easiest to deal
with. If you are extremely protective of your files you could choose to use
Rijndael with a 256-bit key, but it's probably not necessary.
Joe
"Paul Housley" <[EMAIL PROTECTED]> wrote in message
news:95gq0c$a4u$[EMAIL PROTECTED]...
> I want to encrypt some files, which include some excel spread sheets.
> There are some parts of the files which are predictable. e.g. the
> properties, which records the author and other predictable information.
>
> I am concerned that, by knowing what part of the file is supposed to
decrypt
> to, this may help people to find the encryption key.
>
> Any advice, particularly concerning the RC4 algorithm?
>
> Paul
>
>
------------------------------
From: "Joseph Ashwood" <[EMAIL PROTECTED]>
Subject: Re: Rijndael's resistance to known plaintext attack
Date: Mon, 5 Feb 2001 13:20:27 -0800
As it stands now, with any even remotely reasonable amount of
known-plaintext (anything less than the 2^100+ bits) reveals very little.
I'd expect that for the forseeable future, as long as you don't go above
2^90 bits of text there won't be any reasonable attack against Rijndael.
Joe
"Marcin" <[EMAIL PROTECTED]> wrote in message news:95lk4l$1g4$[EMAIL PROTECTED]...
> Hello,
> Can someone comment or refer me to the analysis on resistance of Rijndael
to
> known plaintext attacks?
> Thanks,
> Marcin Kurzawa
>
>
------------------------------
From: Tim Tyler <[EMAIL PROTECTED]>
Subject: Re: TSEPRNG, a secure RNG ?
Reply-To: [EMAIL PROTECTED]
Date: Mon, 5 Feb 2001 21:38:50 GMT
Dan Parisien <[EMAIL PROTECTED]> wrote:
: Race conditions caused by multi-threaded programming causes a large amount
: of headaches to programmers. Why? Because there is no way (theoretically)
: of knowing in which order they will be executed (so you must place locks
: around shared data). That is entropy.
The ignorance of an individual programmer does not equate to entropy, IMO.
: To test the theory that threads get scheduled differently each time (under
: the exact same conditions), I created controlled race conditions. I started
: many threads and made them wait on an event. Each thread has an identity
: (in the test I gave each thread a different number). When the event is
: triggered, all threads try and append to a shared structure in memory.
: Theoretically the order in which they get appended to the structure is
: aleatoric (because if it wasn't, locks and semaphores would be a useless
: waste of resources). The test I ran proved the theory; the simple test
: produced many different results.
This may show that threads seems to get schedulked somewhat differently on
your machine.
Ity certainly doesn't show that the results are random - or that an
attacker can't influence the scheduling to influence the randomness
of the results.
--
__________ http://alife.co.uk/ http://mandala.co.uk/
|im |yler [EMAIL PROTECTED] http://hex.org.uk/ http://atoms.org.uk/
------------------------------
From: Bryan Olson <[EMAIL PROTECTED]>
Subject: Re: DH question
Date: Mon, 05 Feb 2001 21:37:57 GMT
Benjamin Goldberg wrote:
> Is it possible to perform Diffie Helman [either key
> exchange or pke] using GF(2)[x]/p(x) instead of (Z/pZ)?
Yes.
> Is there any advantage? I would expect that in hardware, a GF(2)[x]
> multiplication can be done much faster than an integer multiplication,
> if xor is faster than add; Modular reduction would be likewise be
> faster since xor is faster than subtraction.
Yes, but the best algorithm (known) to break it (Coppersmith's
was the fastest last I heard) is also faster, though still
super-polynomial.
--Bryan
Sent via Deja.com
http://www.deja.com/
------------------------------
From: Tim Tyler <[EMAIL PROTECTED]>
Subject: Re: Where is the encryption hardware?
Reply-To: [EMAIL PROTECTED]
Date: Mon, 5 Feb 2001 21:44:58 GMT
[EMAIL PROTECTED] wrote:
: With all of the obvious benefits of strong cryptography in preventing
: eavesdropping/identification and providing tamper-resistant
: communications, I have but one question: why are there no consumer
: communications products with real encrypted transmission capabilities?
You presume such hardware doesn't exist. In fact there are a number
of hardware cryptography devices for sale.
For example: http://www.ibutton.com/pki.html
--
__________ http://alife.co.uk/ http://mandala.co.uk/
|im |yler [EMAIL PROTECTED] http://hex.org.uk/ http://atoms.org.uk/
------------------------------
From: [EMAIL PROTECTED] (Daniel)
Crossposted-To: talk.politics.crypto,alt.hacker,alt.conspiracy
Subject: Re: OverWrite freeware completely removes unwanted files from hard drive
Date: Mon, 05 Feb 2001 21:52:03 GMT
On Mon, 05 Feb 2001 16:57:13 GMT, Tom St Denis <[EMAIL PROTECTED]>
wrote:
>
>I would argue on super-dense HD's that simply writting FF to the file is
>enough. Not alot of snoopers have the time to break out the 'ol
>electron microscope and read bits "The HardWay (tm)". If I overwrite
>the file with FF the os doesn't keep a backup (or shouldn't) thus
>mission accomplished the file is wiped.
>
>Tom
>
Let us not forget what it would cost to have a HardDisk scanned up to
11 layers deep. Usually, those HD which contained "critical
information" but are no longer used are destroyed (mechanical + heat).
That's the only assuring way :)
best regards,
Daniel
------------------------------
From: [EMAIL PROTECTED] (Padgett 0sirius)
Subject: Re: Phillipine math guy claims to have fast RSA Factoring...
Date: Mon, 5 Feb 2001 05:36:07
Guess I have two questions now that have had a chance to think about it a
bit more:
a) doesn't 1 mod <any positive integer greater than 1> = 1 ?
this makes x=0 the only value for 2^x= 1 mod N
b) if you begin with "all ones" (3x5=15), when do you shift ?
or am I missing something ? (ignorance is curable 8*)
A. Padgett Peterson, P.E. CISSP: Cybernetic Psychophysicist
http://www.freivald.org/~padgett/index.html
to avoid antispam use mailto:[EMAIL PROTECTED] PGP 6.5 Public Key Available
------------------------------
From: Simon Johnson <[EMAIL PROTECTED]>
Subject: Re: Most secure code for US Citizen.
Date: Mon, 05 Feb 2001 21:52:54 GMT
In article <95a62c$mqn$[EMAIL PROTECTED]>,
[EMAIL PROTECTED] (Bill Unruh) wrote:
> In <95a4kn$87m$[EMAIL PROTECTED]> Splaat23 <[EMAIL PROTECTED]>
writes:
>
> ]What are you talking about? He didn't ask for perfect security, just
> ]the current best! I'll admit the context of this encryption is not
> ]known, but you don't need to jump on the man...
>
> And I told him the "best"-- a one time pad. It is provably secure.
> Nothing else is.
Wrong, The OTP is a specialist example of a Secret-Sharing scheme. Many
of which are provably secure.
Simon.
--
Hi, i'm the signuture virus,
help me spread by copying me into Signiture File
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------------------------------
From: "Joseph Ashwood" <[EMAIL PROTECTED]>
Subject: Re: Advice needed
Date: Mon, 5 Feb 2001 13:32:26 -0800
Since you're obviouly willing to take the time to perform multiple hashes.
It would seem more reasonable to me to use the SHA-1 hash as you did with
just the passphrase, use that to key a cipher, and use the cipher for the
actual encryption. It seems to me that this would be the most logical next
step.
Joe
"Janix" <[EMAIL PROTECTED]> wrote in message
news:95luqb$9t5$[EMAIL PROTECTED]...
> Hello,
>
> I want to protect the keys in a key file with a passphrase.
> First, I thought of hashing the passphrase with an arbitrary
> hash algorithm (e.g. SHA-1), xoring the hash with the key
> and storing the result (hash(passphrase) xor key) in the
> key file. But then, I realized that if someone gets to know
> one of the unencrypted keys, he could recalculate
> hash(passphrase) and thus be able to read the whole
> content of the key file. So my second approach is to xor
> the key with hash(keyID, passphrase) instead, before
> storing it. Is this idea as clever as I think or are there any
> drawbacks I should consider?
> I would be grateful for any advice you could give me.
>
> Regars, Janix
> [EMAIL PROTECTED]
>
>
>
------------------------------
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