A proper law

[Quentin Campbell]

> -----Original Message-----
> From: David Hansen [mailto:davidh@spidacom.co.uk]=20
> Sent: 06 March 2003 14:39
> To: ukcrypto@chiark.greenend.org.uk
> Subject: Re: A proper law
>=20
[snip]
> Part of the trouble with these machines [enciphering teleprinters]=20
> was the way the key was=20
> "entered". It took considerable time for the cipher clerk to set up=20
> all the little swinging pins on all the wheels. This made them not=20
> keen to change settings too often. [snip]

A pin setting awkwardness also applied to the American M209 cipher
machine so settings were used much longer than they should have been. As
a result the Germans were regularly breaking this system. It was anyway
considered by the Americans as a fairly insecure system and so used only
as a field cipher.

One lesson modern day intelligence agencies have carried over from
war-time experiences is that it is often easier to capture
keys/clear-text than to break the cipher. This much was acknowledged in
the Walsh Report (UKCRYPTO passim).

Quentin