Army signals security & "Clansmen" series radios

[Owen Lewis]

----- Original Message -----
From: "Dave Howe" <DHowe@Hawkswing.demon.co.uk>
To: <ukcrypto@maillist.ox.ac.uk>
Sent: 08 September 2000 00:36
Subject: Re: Army signals security & "Clansmen" series radios


> > ... traffic analysis should not help. It should detect the broadcast but
> > cannot tell how many recipients there were and even less who those
> recipents
> > were. If you assume that the recipients must in turn transmit
> > acknowledgement and that these will be detected:
> An assumption here is that the Public key could have and therefore
probably
> has fallen into unfriendly hands; assuming they now have a mapping of
Public
> Key to identifiable designation, they can pull the PK outer wrapper and
> identify the recipients, even if not the message content.

Interesting thought. It indicates a possible disadvantage in the use of a PK
system. One way of limiting the risks arising from a loss of keymat is if
all message addressees change their address on some frequent basis and a
second is also to change the keymat on a frequent basis. However, though not
impossible for such to be incorporated in a PK system, such practices would
seem to work against the grain in a PKI.
>
> > Would one expect that traffic analysis is likely to help identify the
> > strength, composition and location of a nuclear strike force from a
> homeland
> > broadcast half a world away?
> Nope, that should not happen. I won't say it can't (if they are downlinked
> from a satelite, unless ALL messages are automaticallly sent via all
> satellites, you can assume that a recipient is somewhere inside the
> footprint; ideally, that footprint should be worse than useless for
> location, but sillier things than precisely-targetted transmissions have
and
> will happen)

But the terms broadcast and precisely targeted are somewhat antipathetic.
Satellite footprints are large enough even to incorporate more than one
theatre of military operations. Skywave transmissions have no footprint in a
meaningful sense; even less do groundwave transmissions.



Owen