I've seen answers here and elsewhere discussing how well the WWII Enigma could hold up to modern cryptanalysis, however, those answers always seem to assume the WWII conditions where the Germans had a limited number of rotor constructions, repeated patterns of plain text, and the Allies had access to a lot of the info about the rotors, their wirings and the limited combinations in use.
What if a software based enigma were executed with the following conditions:
- 38 characters (versus 26)
- ten rotors
- the rotor settings, stecker settings, and rotor permutations themselves change with each message, all pre-planned using a cryptographically secure PRNG (i.e., the operator no longer chooses and transmits settings in a preamble)
- assume (for sake of argument) no cribs and physical security - i.e., the attacker might have access to the encryptor, but not to any keys
How well would this hold up to modern cryptanalysis using super computers or networks? How long might it take to brute force it?