Russian M-125 Fialka Cipher Device(glennsmuseum.com)

33 pointsby luuvor 12 Jahren2 comments

http://www.glennsmuseum.com/encryption/encryption.html

1 comments

jeppervor 12 Jahren

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

EthanHeilmanvor 12 Jahren

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

nomaningmevor 12 Jahren