Re: Steganography covert communications - Between Silk andCyanide

2002-01-05 Thread Ben Laurie 

Matt Crawford wrote:
 
  David Honig wrote:
   Unbeknown to the latter, Marks had already cracked General de Gaulle's
   private cypher in a spare moment on the lavatory. -from the obit of Leo
   Marks, cryptographer
 
  But this was because it was, in fact, one of his own ciphers.
  Cheers,
  Ben.
 
 Not one that he invented or approved of, but one that he knew and had
 to work with, yes.

Indeed, it was the cipher he inherited (and spent much time and energy
to have replaced, for excellent reasons).

Cheers,

Ben.

--
http://www.apache-ssl.org/ben.html



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Re: Steganography covert communications - Between Silk andCyanide

2001-12-31 Thread Arnold G. Reinhold 

At 2:59 PM -0800 12/30/01, John Gilmore wrote:

Along these lines I can't help but recommend reading one of the best
crypto books of the last few years:

   Between Silk and Cyanide
   Leo Marks, 1999

This wonderful, funny, serious, and readable book was written by the
chief cryptographer for the 'nefarious organization' in England which
ran covert agents all over Europe during WW2 -- the Special 
Operations Executive.

What makes this book so excellent is that Marks was not just the 
chief cryptographer at SOE, he was the *only* cryptographer. He got 
to do everything. A young amateur crypto enthusiast, he didn't make 
the cut for Bletchley after basic cryptanalysis training due to a bad 
case of smart ass and was sent down to SOE. He almost failed to get 
that job when it took him all day to decipher a test message. He 
didn't realize he had been supplied the key.

... He taught the receiving code
clerks in England how to decode even garbled messages, rather than
asking agents to re-send them.  (Re-sends of the same text gave the
enemy even more trivial ways to crack the codes.)

More important, it sharply increased their risk of being caught by 
German radio direction finders. Agents had been captured or shot in 
the middle of re-transmissions.

At 1:21 PM + 12/31/01, Ben Laurie wrote:
David Honig wrote:
 
  Unbeknown to the latter, Marks had already cracked General de Gaulle's
 private cypher in a spare moment on the lavatory. -from the obit of Leo
 Marks, cryptographer

But this was because it was, in fact, one of his own ciphers.

That's not quite fair to Mr. Marks. General de Gaulle used a double 
transposition cipher similar to the one the OSE had been using since 
before Marks got there, though Marks had to discover this on his own. 
Marks' codemaking efforts were directed toward improving that cipher 
and replacing it with a one-time pad. One advantage of the one time 
pad was that messages could be short, reducing the DF risk. Double 
transposition cipher required a minimum length, 200 letters, lest 
they simply be anagramed.

I have a review of the book at 
http://world.std.com/~reinhold/silkandcyanide.html

Arnold Reinhold





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