[Cryptography] Leo Marks' 1998 talk about WW2 SOE code-making and breaking

[zeb at qtt.se]

> On 2026-01-25 06:00, Peter Fairbrother wrote:
> 
> Problems: you can't know what these codes are, in case you are caught
> and tortured.
> 
> you can't give the agent anything physical in case the Gestapo find it.
> 
> you can't say to the agent, make up something random for the first
> message and repeat thereafter, because the first message needs to be
> authenticated.
> 
> 
> So how do you tell the agent what his secure and distress codes are?

That seems impossible.

I suppose you actually _could_ give each agent something physical (and 
individual), like a sealed envelope, to be burned or eaten or 
self-destruct, after remembered.

So what's the answer?

Z
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://www.metzdowd.com/pipermail/cryptography/attachments/20260126/ebcc545a/attachment.htm>