Re: Enigma machine strenght using a computer

"=?iso-8859-1?q?Jean-Fran=E7ois_Michaud?=" <cometaj@xxxxxxxxxxx> writes:


Unruh wrote:
"=?iso-8859-1?q?Jean-Fran=E7ois_Michaud?=" <cometaj@xxxxxxxxxxx> writes:

Hello,

I was wondering what kind of encryption strenght we were looking at for
an enigma machine with say 512 rotors, each rotor having 256 (0 to 255)
states to rotate into.

I know it depends on how the rotors move but what bounds are we looking
at? At least what and at most what?

Sorry, no idea what you are asking. bounds to what? Strength? How would you
measure strength?

Hehe, that was my question. I'm actually asking the question, I don't
have an answer for you :). I'm thinking that variations to the way the
rotors move can add additional complexity if say another complex
machine with similar characteristics determines how the rotors of the
encrypting machine move. (swaping rotors, rotor rotating clockwise or
anti clockwise, etc).

Note that your key space is HUGE.
256^512 = 2^4096-- ie a 4096 bit key space. (or if the rotors can be
arbitrarily arranged, another factor of 512! of key space-- another 4000
bits approximately.

So we're roughly 8094 bits of encryption strenght as a lower bound for
a single machine without complex rotor evolution since the rotors can
indeed be arbitrarily arranged on.

No, this key space includes all possible initial states of th e rotors and
all possible swaps of the rotors. Since the evolution of the rotor
positions MUST be deterministic (on the intial state of the machine and on
the message-- both encrypted and plain text, since the same evolution must
occur for both) , that adds no further entropy.

No idea what you mean by 8094 bits of encryption strength?



Why are you asking?

Just wondering. I coded something like this and I was wondering how
strong the encryption was.

Regards
Jean-Francois Michaud

.

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