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

[Kent Borg]

On 1/19/26 3:53 PM, Peter Fairbrother wrote:
> On 19/01/2026 17:16, Kent Borg wrote:
>
>> Question: What is a "worked out key"?
>
> "Worked out keys" weren't actually worked out at all, they were 
> randomly generated subkeys similar in use to the non-random subkeys 
> agents worked out from a poem.

Very cool.

So the hierarchy was:

- OTP for regular traffic. Destroy the key material after use, unbreakable.

- WOK if necessary. More compact keys than OTP, possibly easier to use 
than OTP. Somewhat more secure than the poem, familiar procedure.

- Last resort, poem-based. Infinitely compact (memorized key source). 
Required preparation step, ciphertext susceptible to being cracked, SOE 
agent could be tortured to maybe gain access to all ciphertext using 
that poem.


Thanks,

-kb