Are basic principles flawed?

[Matthew Pemble]

Nic.Alderson@yeg.co.uk wrote:
> 
> Consider the following:
> 
> 1) I am intent on hiding my organisation's activity - for nefarious
> reasons.
> 2) I design an encryption tool to encrypt the meaning (not the content)
> of a document delivering an output in plain text as a readable document.
> In simplest form this could be no more than word substitution - but this
> should be vastly more sophisticated.

This is encoding as opposed to encipherment.  Codes are difficult to
break for very low numbers of short messages, but as the data volume
becomes higher, patterns emerge.

> 3) I encrypt this output using a second tool to scramble the content (or
> maybe I don't bother).

<snip>

> It undermines the basic tenet of these approaches to snooping and RIPA

Codes are difficult to generate and use effectively, which is why so
much effort is put into ciphers.  You are correct that "Send 2 and
sixpence, we are going to a dance," is meaningless to automated systems,
but if correlated with a move of reserve troops and an attack, the next
time a similar message is sent and intercepted, assumptions will be made
and automated filters updated.

Matthew Pemble
Eur Ing CEng MIEE MBCS AIMgt

Technical Director
Idrach Ltd

Tel:	+ 44 (0) 7050 128620
Fax:	+ 44 (0) 1324 610367

Email:	matthew@idrach.com
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