Cryptography Reference
In-Depth Information
random session keys. Furthermore, the integrity is checked by means of an
MD5 hash sum (which is secure in this context).
The Python script language is ideally suited for such applications, since it has
fast long-number arithmetic built in. Moreover, it is a modern and extremely
easy-to-learn language with interfaces to C/C++ and other languages (visit
www.python.org
for more information). Thanks to its large number of mod-
ules, hardly a wish remains unfulfilled (it doesn't always have to be Perl —
Python programs are generally much easier to maintain and understand).
The software is covered by the usual PSF license for Python scripts, which
means that it may also be used commercially. It has been tested under
Linux only to date. The software and documentation area the Web site under
PD/secshare
.
6.2.3 Shared Secrets and Nuclear Fission
There is a very serious motivation behind the development of secret splitting
and secret sharing: these methods served to secure nuclear weapons. Following
the Cuba missile crisis, there was concern that a world war could start by
accident — for example, by a rogue or hysterical commander feeling that 'if
only they knew in Washington how bad things were here, they would let us
use the bomb'.
President Kennedy's response was to order that almost all nuclear weapons
1
should be brought under 'positive control'. This meant that missile warheads
could be activated with a secret code only. But it would have been far too dan-
gerous to use the same key for all warheads; a maintenance engineer could have
recovered it. So they needed a group key for smaller quantities of weapons.
At the same time, nuclear weapons were not to be used without the Presi-
dent's approval.
This was the point where secret splitting came in handy: local commanders
knew part of the group key. Together with the universal key made known
by the President, the group key produced a key valid for a specific batch of
weapons (now you have a vague presentiment of what's in Putin's famous little
suitcase).
If a Soviet 'surprise raid' were to destroy the US army's top echelon, it would
presumably no longer be possible to learn the universal key. The solution in
1
Except for the 'nuclear demolition munition', which is taken from its storage depot to its
target and detonated using time fuses.
