Re: Enigma machine strenght using a computer

They are complex in structure, but not complex to implement. They are
in fact very easy to implement in code. If they potentially allow for
very strong encryption even if they are slow, does it matter? It all
depends on the context in which it's used.

I can't speak for Unruh but I think the point he is making is this.

You're right that computers would allow us to implement an Enigma like
cipher with rotors that spin backwards, forwards, stop and start based
on other rotors, change their values according to the phase of the moon
etc..

But is this useful? Is this a good way to get security on modern
hardware?

Electromechnical machines were used for encipherment because they made
encryption less error-prone and they were a cost effective way to get
security for their time.

Cryptography on modern hardware is all about getting the job done with
the fewest resources. A cipher that uses fewer resources can target a
greater number of platforms. If a cipher takes 4 gigs of RAM, it can't
be used on a smart-cart, for example, or mobile phones and things of
that ilk which all limit its usefulness.

It is therefore prudent to use the instructions provided by the
majority of CPUs that operate fastest.

This is why you see a lot of ciphers using XOR, ANDS, Circular shifts
and the like combined with table look-ups to provide security. They're
fast, compact and have well understood cryptographic properties.

This makes these operations a superior foundation on which to construct
a cipher than a rotor based cipher design.

Simon.

.

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