The German SZ42 Cipher Machine Explained

#cryptology, #cryptography, #cryptanalysis
In this video, I explain the Lorenz SZ42, a ciphermachine used by the Germans during WWII. It was used for encryption of high-level communications beginning in mid 1942. The machine encrypts Baudot code using a pseudo-random generated keystream.
In the video, I explain how the cipher machine works and we analyze its keyspace size and unicity distance. We also create a workspace in CrypTool 2 to encrypt and decrypt text using the new SZ42 component.
If you are interested in learning the fundaments of cryptology, let me invite you to have a look at our video series about the basics of cryptology, also for beginners: • Basics of Cryptology -...
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[@AarreLisakki]

there's a small typo in the keyspace calculation -- in total keyspace size calculation, when writing down the formula, you accidentally repeat the number 2^150 (from the Chi wheels keyspace) also for the Mu wheels keyspace size, instead of using the value of 2^98 as calculated in the previous step.
But, doesn't affect anything as despite the written values being off, the total keyspace size has nevertheless apparently been calculated using 2^98 as intended; 2^150 * 2^253 * 2^98 = 2^501
Thx for making these vids, I very much enjoy learning about various historic ciphers from them!

[@scamalach]

What a great explanation of the most infamous machine in WW2. Thanks for doing this!

[@CryptographyForEverybody]

Thank you 😊. Happy you liked the video 🙂. Greetings Nils

[@chrisst8922]

I believe that this particular machine was the one used by Kesselrings army.

[@timetraveller6643]

Another fascinating description. Thank you Nils.
The mechanical encryption machines all try to do the same thing; Generate a near random long period pseudo-random number.
Have modern math theories suggested any new approaches to designing a practical mechanical pseudo-random number generator with more perfect distribution and super long periods?
Are gears and wheels the only components considered? Are there no rod, lever, or chain based machines? (paper tape seems much too fragile to me)
I like the sliding tiles in John Byrnes Chaocipher.
Perhaps there's a way to automate Bruce Schneier's Pontifex (Solitaire) using tiles.
--Molly J.

[@CryptographyForEverybody]

Hiho,
I think after the invention of electronic-based and computer-based ciphers, there was no need for working on strong mechanical cryptographic devices. I think two of the most secure ones (and therefore best pseodo-random ones) are the M-209 and the SG-41, which basically is designed the same way the M-209 is, and the CX-52.
Greetings,
Nils