
Russian M-125 Fialka Cipher Device - luu
http://www.glennsmuseum.com/encryption/encryption.html
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jepper
Really interesting post. Does it have the same weakness as Enigma devices,
i.e. that the input char can never become the output char ( encrypt(a) is
never a)? This significantly reduces the search space.

[https://en.wikipedia.org/wiki/Cryptanalysis_of_the_Enigma](https://en.wikipedia.org/wiki/Cryptanalysis_of_the_Enigma)

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EthanHeilman
The Engima has that weakness/property because it uses a reflector which
reflects the current back through the rotors. The M-125 also uses a reflector
so I would guess that the weakness/property exists, but it is likely hard to
exploit than the enigma.

Let me explain, the M-125 uses a card reader to alter the input characters
sent to the rotors. The rotors aren't being applied to raw input.

input -> card transformation -> rotors/reflector/rotors -> output

>"The activated wire corresponding to the input character wire goes to the
card reader (the slot on the left side). Holes punched in the card control the
swapping of characters. So, our A is translated to a T. [then it is sent to
the rotors]"

After the card reader transformation the "never the same character" property
would hold, but the card reader makes it significantly more difficult to
exploit. That is, if you could guess the output after the card reader
transformation you can apply the attack, but you'd probably have to guess the
card reader transformation key first

Note that the Enigma had a plugboard[0] for a similar purpose but was less
effective since most characters were left unchanged by the plugboard.

[0]:
[https://en.wikipedia.org/wiki/Enigma_machine#Plugboard](https://en.wikipedia.org/wiki/Enigma_machine#Plugboard)

