[Cryptography] Practicality of codebook in current-day secret communications

[Tom Mitchell]

On Wed, Feb 24, 2016 at 11:58 AM, mok-kong shen <mok-kong.shen at t-online.de>
wrote:

>
> Codebook appears, if I don't err, to be an antiquitated topic rarely
> touched upon in discussions of modern cryptography.
>

Absolutely could be and is a critical part.
Not antiquated...  but often ignored by the press because
they are effective.

Almost all the interesting silicon design programs have one
or more code names. Some are marketing some are engineering.
Should a company discover their code name in the press they know
that someone was talking in in public or to the media.

Part of Snowden's big disclosure was the names of programs.
Those names now on the internet make finding  are validation
of code words and facilitates correlation of rumors.   Compartments
of secrets behind a word no longer lead back wit clarity to the short list
of
insiders.

The notable historic model for this is the Japanese encryption of messages
in WW2.
The messages was encrypted but islands, bases, etc had code names.

One encrypted sequences of messages indicated an attack on target XYZ.
The American command had no  code book to know where XYZ was.   A message
was sent in the clear by the Americans that there was a water supply
problem.
That message was picked up by a listening post and sent back home.   It used
the code name XYZ and that XYZ had a water supply problem.

http://www.sjsu.edu/faculty/watkins/midwaybattle.htm

...."some in authority that feared the target might be Hawaii or the West
Coast. They did not want  defense
forces assembled at Midway if Hawaii was going to be the target.


"The situation was resolved sending a message to Midway by secure undersea
cable telling them to send
an unencoded message by radio to Hawaii announcing that their water
desalinization plant had failed and
that they had only a two week supply of fresh water. Hawaii sent back a
message that the replacement plant
was on its way. From the flurry of Japanese messages that resulted from
this ploy it was obvious that Midway
was to be the target."

All the old school methods apply.  Two identical paperback books.  find a
word, PageLineCount=word  or is it LineCountPage

Recall that Tora Tora Tora was sent in the "clear".
All the planning was communicated in person, via encrypted radio message,
encrypted hard copy.
Not just one code and method:
https://en.wikipedia.org/wiki/Magic_(cryptography)
The "Post War Debate" section is being replayed ...
Despite reading these messages no message said attack Hawaii.  There was a
handful of
messages that in hindsight show that Hawaii was being watched and could be
a target.

The old code books are interesting.  Some are data compression.  Some
transmit secrets.
http://howwethink.nkhayles.com/codebooks/texts/
Text messages and Morris code have a lot in common. Especially when
broadcast via twitter
or to a group.


*  -- *
  T o m    M i t c h e l l
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.metzdowd.com/pipermail/cryptography/attachments/20160224/c10ce673/attachment.html>