

Parallel Algorithm Leads to Crypto Breakthrough - prat
http://www.ddj.com/222600319

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cperciva
Ok, I understand the "parallel algorithm" bit... but where's the "crypto
breakthrough"? Breaking 56-bit DES? That was old news over a decade ago.

~~~
redmage
I think their point was this:

    
    
      When using a Pico FPGA cluster, however, each FPGA is able
      to perform 1.6 billion DES operations per second. A cluster
      of 176 FPGAs, installed into a single server using standard
      PCI Express slots, is capable of processing more than 280
      billion DES operations per second. This means that a key
      recovery that would take years to perform on a PC, even
      with GPU acceleration, could be accomplished in less than 
      three days on the FPGA cluster.
    

So, they managed to brute-force DES a lot faster. No crypto breakthrough,
please move along. :)

This should have been titled "FPGA cluster brute-forces DES in record time" or
something like that.

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cperciva
_FPGA cluster brute-forces DES in record time_

Even that isn't true. Deep Crack took 56 hours (matching the "less than three
days" claimed in the article), while the combined Deep Crack + Distributed.Net
effort took less than 24 hours.

~~~
redmage
Sorry, my bad. I didn't bother to research, just pulled that from the article.

    
    
      Pico Computing has announced that it has achieved the
      highest-known benchmark speeds for 56-bit DES decryption, 
      with reported throughput of over 280 billion keys per
      second achieved using a single, hardware-accelerated server.

~~~
cperciva
Ok, so 12 years after Deep Crack they've managed to get triple its
performance. I can't say that I'm very impressed.

~~~
sp332
Deep Crack used specialized ASICs. The breakthrough is that these general-
purpose (reprogrammable) FPGAs are actually faster.

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CWuestefeld
I've often wondered how you know when you've actually found the solution.

 _The massively parallel algorithm iteratively decrypts fixed-size blocks of
data to find keys that decrypt into ASCII numbers. This technique is often
used for recovering the keys of encrypted files containing known types of
data._

This doesn't make sense to me. I mean, what if I didn't encrypt ASCII numbers?
What if it's, say, an email message that's predominantly text in, say, UTF-8
or UTF-16?

And it seems to me that as we develop richer ways to _encode_ data, it also
makes it correspondingly difficult to decrypt that data.

~~~
cperciva
The field of cryptography developed in the context of nation-state actors and
idiots who use crypto wrong. (Come to think of it, not much has changed.) In
WW2, a lot of crypto was broken thanks to known plaintexts -- e.g., "Today's
weather is..." -- or chosen plaintexts -- e.g., "Submarine sighted at...".
This was made easier, of course, by the fact that military structures tend to
use very consistent communications formats.

You're quite right that you can slow down a brute force attack by making the
input data hard to recognize -- one trivial approach is to pad it to a large
size and then apply an all-or-nothing transform -- but by the time this sort
of mechanism was feasible, brute force key searches stopped being useful due
to increased key lengths.

~~~
eru
As far as I know the allies used to spot the plaintext word "EINS" in the
Enigma ciphertexts. This was helped by the omission of numbers --- or anything
besides letters --- from the Enigma's alphabet. They did not even have a space
key.

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jacquesm
That's running 10 times faster than this rig:

<http://www.copacobana.org/>

And it cracked DES in about 9 days iirc, @35 billion keys / second.

