M4 Message Breaking Successful

Stefan Krah succeeded in breaking the first of 3 original Enigma Kriegsmarine M4 messages. The M4 Project attemps to break these 3 Naval messages with the help of distributed computing. The messages, believed to be unbroken until today, were intercepted in the North Atlantic in 1942.

The encrypted Enigma messages were originally published by Ralph Erskine in a letter to Cryptologia. To perform the ciphertext-only attack, Krah used a combination of brute force and the hill-climbing algorithm. The program runs through all possible settings of the Enigma, except the plugboard. The plugboard settings are a huge portion of the key space. Omitting them during the attack saves a hugh amount of time.

For each machine setting, the hill climbing algorithm is used to optimize the plugboard settings. The algorithm tries to optimize the plugboard settings, by changing the plugboard, step by step. After each step, the 'quality' of the result is determined by a scoring function. If the score is better, the change is retained. Yesterday, this approach resulted in a first successful break into a Naval message (read the broken messages).

You can read about the M4 Project and the story of U-boat U-264 on my website. You can use my Enigma Simulator to verify the results by using Stefan's recovered machine settings and decipher the message yourself.

Russian Fialka in Detail

Russian M-125 Fialka

August last year, I wrote a site review on the famous Russian Fialka cipher machine. This beautiful piece of Cold War technology, introduced in 1965, was top secret until the 90's.

 

Paul Reuvers from Crypto Museum has composed a magnificent detailed description of the M-125 Fialka. The page includes many detailed drawings, wiring diagrams and a manual to the Fialka. In his manual, you'll find the history on Fialka and a very complete technical description. A must for crypto geeks!

He also published two very nice Fialka simulation programs, for both Fialka M125-xx and M125-3xx, written by Chernov. Some time ago, Paul also wrote a beautiful Enigma Cipher Machine simulator for RISC OS, and created an electronic DIY building Kit, the Enigma-E, which is fully compatible with the real German Enigma.