[Cryptography] Imitation Game: Can Enigma/Tunney be Fixed?

[Ben Laurie]

On 5 January 2015 at 17:41, Tony Arcieri <bascule at gmail.com> wrote:
> On Sun, Jan 4, 2015 at 3:56 PM, Henry Baker <hbaker1 at pipeline.com> wrote:
>>
>> Since The Imitation Game is playing & is quite likely to win some awards,
>> I was wondering if anyone has written an analysis of the Enigma & Lorenz
>> encryption systems using 2015 eyes?
>
>
> Enigma is fatally flawed in its current design, AFAIK. Due to the nature of
> how its rotors operate, it can't encrypt a letter to itself, introducing a
> statistical bias into the ciphertext.
>
> Enigma would need to be modified so all letters have equal probabilities.
> Someone who knows the intricacies of these rotor machines better than me
> might know what's involved.

Surely not as simple as that - this flaw allowed them to automate a
brute force attack (and perhaps reduce its cost, but my understanding
of the Bombe is that it was fully brute force - reductions came from
intelligence of various kinds).

Increasing the cost of the brute force would still be effective.