It would be true if they used a fixed set of huffman codes for which
lower case letters had shorter codes; this is reasonable if you're
compressing large amounts of text, since most of it is lowercase.
--
Mike Stay
Programmer / Crypto guy
AccessData Corp.
[EMAIL PROTECTED]
I seem to recall hearing of a signature scheme wherein the message is
recovered from the signature. Does this ring a bell for anyone? Any
pointers?
--
Mike Stay
Cryptographer / Programmer
AccessData Corp.
mailto:[EMAIL PROTECTED]
Suppose someone discovers a way to solve NP-complete problems with a
quantum computer; should he publish? Granted, the quantum computers
aren't big enough yet, but the prospects look bright for larger ones in
the near future. It would break all classical cryptography.
--
Mike Stay
Cryptographer
Ulrich:
>Can you explain the halfing effect on the key length? Or may be you
>have some pointers to the literature on that?
Look up "Grover" on the Los Alamos National Labs pre-print site
http://xxx.lanl.gov/find/quant-ph
Searching a space with half the keylength is searching a space with the
sq
Is it possible to choose a seed, multiplier, and modulus for a linear
congruential generator such that it duplicates any finite list of
positive integers?
[No, but I'll let others expand or do it in another message. --Perry]
--
Mike Stay
Cryptographer / Programmer
AccessData Corp.
mailto:[EMAIL
Arnold G. Reinhold wrote:
>
> You can see that Perry is right by a simple counting argument. Say the word
> size is m bits. There are 2**(3*m) cvombinations of seed, multiplier, and
> modulus and there are (2**m)! possible arangements of the values. The
> latter is much bigger for m > 2.
>
>
Hans wrote:
>When implementing PGP base encryption, is this implementation MUST use
>symetrically Algorithms ?? Is it possible to use only the >public/private key ?
There currently isn't a way to do it under the OpenPGP Draft. Why would
you want to? Symmetric algorithms are generally one or t
I wrote:
>just enough room to store a password 16 unicode characters long, the >maximum length
>password you're allowed
It's actually 15 characters, so any prime between 2^240 and 2^256 will
work.
--
Mike Stay
Cryptographer / Programmer
AccessData Corp.
mailto:[EMAIL PROTECTED]
The encryption in MS Word / Excel uses 32 *bytes* of salt. It's
interesting to me that this is just enough room to store a password 16
unicode characters long, the maximum length password you're allowed.
Just choose the first prime smaller than 2^256, one of say, 1024
multipliers, and modular mu
There's no real concept of "distance" between elements of a group, and
yet if you were to consider operations on, say, a rubix cube, it's
obvious that some states are further from "solved" than others. That's
because we can't "do" a general operation on the rubix cube in just one
step; we have to
I have a set of unit vectors, but don't know their coordinates, or even
the dimension of the space they span. I'm given the angle between each
pair of vectors in units of some unknown "unit angle". I'd like to find
the smallest dimension into which the set fits, as well as the range of
values th
What does decorellation do?
--
Mike Stay
Cryptographer / Programmer
AccessData Corp.
mailto:[EMAIL PROTECTED]
With N key bits, there are 2^N different subsets of key bits. If you
fix a plaintext, then each ciphertext bit is an N-to-1 boolean
function. Is there any way to show that there is no subset of key bits
whose parity is a good linear approximation of the function?
--
Mike Stay
Cryptographer / Pr
The ecc discrete log problem is given points A and B, find integer x
such that xA=B if it exists. I assume that most crypto implementations
of ecc use finite fields; in a finite field can you assume that x
exists?
--
Mike Stay
Cryptographer / Programmer
AccessData Corp.
mailto:[EMAIL PROTECTED]
There are several (five, that I've found) linear approximations of the
*entire* S-box that hold with probability 7/256. Is that useful?
--
Mike Stay
Programmer / Crypto guy
AccessData Corp.
mailto:[EMAIL PROTECTED]
How many ways can one form an abelian group with N symbols? Note that
I'm not asking how many groups there are of order N, since isomorphisms
count separately, and it's not just the number of abelian groups times
the number of permutations of the symbols, since the identity element
isn't preserve
Generally, they'll just be recovering passwords. Then it's easy to show
that the plaintext matches the ciphertext. They don't have to reveal
where the password came from, of course, merely that it decrypts the
file.
>If you can not reveal how you descramble it, doesn't that mean you >can't be
Our company works with the FBI a lot. We provide the software they
actually use to recover passwords.
The majority of software out there uses access-denial: the encryption /
ofuscation doesn't depend on the password. But to be acceptable in
court, you have to prove that you didn't change a si
I seem to recall someone saying that if you can get one bit of an RSA
message, you can get the whole thing. Or maybe it was the key. Does
anyone know where I might be able to find out more about this?
--
Mike Stay
Programmer / Crypto guy
AccessData Corp.
mailto:[EMAIL PROTECTED]
I know they got one guy here in the States for sending a death threat
across state boundaries (went over the internet out of state, then back
in again).
--
Mike Stay
Programmer / Crypto guy
AccessData Corp.
mailto:[EMAIL PROTECTED]
I wrote the author of the challenge. He responded (quoted with
permission)
If you had received my previous email, with accompnaying URL (below),
you would know how I encrypted this message and have my source code.
> Will you provide source to the encryption code?
Yes. See:
http://www.w
I guess the question is, how much entropy is in your average compressed
jpeg?
--
Mike Stay
Programmer / Crypto guy
AccessData Corp.
mailto:[EMAIL PROTECTED]
On the Los Alamos Preprint site (xxx.lanl.gov) today:
quant-ph/9910072 [abs, src, ps, other] :
Title: Quantum secure identification using entanglement and catalysis
Authors: Howard N. Barnum
Comments: 7 pages; no figures
I consider the use of entanglement between two parties to enable one to
au
Consider functions of one variable whose domain and range are both
{0,1,2,...,n-1}. There are n^n possible functions. How many of these
are linear [i.e. F(a+b) = F(a) + F(b) + c, where c is the same for all
a,b (if it were different, that would be trivial)]? For any one
definition of +, there w
Before OSR2, Windows PWL (cached password database) files reused the
same RC4 stream for known plaintext and the cached passwords. Someone
exploited this and published code. Apparently, MS has fixed the
problem. PWL files under '95/OSR2 and '98 are protected with a single
RC4 stream whose 128-b
I wrote:
>Resources and passwords don't have to conform to anything; they're
>arbitrary binary strings.
The PWL file is a database of (type,name,resource) triplets; it can
store up to 255 of these; I don't know how long each can be.
--
Mike Stay
Programmer / Crypto guy
AccessData Corp.
mailto:[E
Does resistance to linear cryptanalysis mean that there is *no* linear
approximation to the entire function with a large enough bias to
exploit?
--
Mike Stay
Programmer / Crypto guy
AccessData Corp.
mailto:[EMAIL PROTECTED]
Also check out RedCreek Ravlin.
"Michael Enk" <[EMAIL PROTECTED]> on 11/03/99 05:11:25 AM
To: [EMAIL PROTECTED], [EMAIL PROTECTED]
cc:(bcc: Christopher St Clair/OH/BANCONE)
Subject: HOWTO: Encryption on local LAN
Hi all,
I have run into a bit of a problem. I am looking for a 'bl
Are there any kinds of primes I should avoid when picking a modulus for
an ElGamal system?
--
Mike Stay
Programmer / Crypto guy
AccessData Corp.
mailto:[EMAIL PROTECTED]
On average, you'll find one N-bit collision after looking at O(2^(N/2))
random N-bit strings; how long does it take, on average, to find k
collisions? O(k*2^(N/2))?
--
Mike Stay
Programmer / Crypto guy
AccessData Corp.
mailto:[EMAIL PROTECTED]
I wrote:
>O(k*2^(N/2))?
It has to be faster than that by a counting argument. How much faster?
--
Mike Stay
Programmer / Crypto guy
AccessData Corp.
mailto:[EMAIL PROTECTED]
I've got something with around 100 bytes of ram and an 8-bit multiply.
Is there an authentication mechanism that can fit in this?
--
Mike Stay
Programmer / Crypto guy
AccessData Corp.
mailto:[EMAIL PROTECTED]
Several people have suggested using a MAC; my problem is that the
opponent can reverse-engineer the chip and find the key. I was hoping
to give the chips a public key and have it encrypt a challenge that I'll
respond to. On my side, I'd need to prevent chosen-cipehrtext attacks.
--
Mike Stay
Pr
Eric wrote:
>No matter how well concealed (stego)or how well encrypted (crypto),
>does he have any way of notifying his friends that they should
>look here without alerting the enemy of his attempts to communicate?
It's the same challenge as secret key vs. public key. If you have no
prior arrang
PGPDisk? Also BestCrypt lets you write your own encryption module.
>Does anybody know any good Win95/98 utility providing connectoids seen >by the user
>as folders, so that any file moved to and from them get
>automatically encrypted and decrypted? Something like Encrypted Magic
>Folders by PC
You can get away with as few as seven bytes of plaintext and 2^40 work
if you have other files in the archive. Five of the thirteen bytes are
only used for filtering, so if you have other files you can use the
password check bytes instead of known plaintext bytes. Also, in
kocher's attack, you c
Today on http://xxx.lanl.gov/list/quant-ph/new
quant-ph/0006109 [abs, src, ps, other] :
Title: Unconditionally Secure Quantum Bit Commitment Is Possible
Authors: Horace P. Yuen
Comments: 12 pages
Bit commitment involves the submission of evidence from one party
to another s
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