The GRANIT/160 Cipher Explained - A GDR Stasi Spy Cipher

#cryptology, #cryptography, #cryptanalysis
In this video, we explain the GRANIT/160 cipher. It was used by spies of the GDR (German Democratic Republic) who spied in West Germany. A famous spy who used the cipher and who was caught was Günter Guillaume, who spied near Willy Brandt. In the video, we explain how the agent used the cipher, created keys, etc. Finally, we do this also in CrypTool 2, we encrypt and decrypt using the GRANITE cipher.
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 -...
Links mentioned in the video:
- Klaus Schmeh's German blog article about GRANIT: scienceblogs.de/klausis-krypt...
- Jörg Drobick‘s German homepage: scz.bplaced.net/m.html#granit
You can download the latest version of CrypTool 2 from here: www.cryptool.org/en/ct2/downl...
Visit my blog: www.kopaldev.de
Join Discord server: / discord

[@trimethoxy4637]

excellent turorial, thank you very much!

[@CryptographyForEverybody]

Thank you, happy you like it 🙂👍

[@AarreLisakki]

Thank you for this explanation, but I have a question about the indicator group calculation. If I understand you correctly, one is to add the page concatenated with the line number (as a single 5digit number) with the secret key. But, isn't that key supposed to be reusable? And if I were to add the page/line number with the same key again for the next message, isn't this like reusing a one-time pad? I guess we don't have any kind of crib to presume as its just random page and line numbers, so maybe it can't be a problem here -- is that what's going on to make this procedure here nevertheless fine, or something else?

[@michaelheynemann4267]

Verstehe ich nicht. Es müsste doch zwei Indicator-Groups geben. Für jede Transposition eine, da ja zwei Seitenangaben eingebaut werden müssen. Oder wird die doppelte Gruppe der ersten bei der zweiten Transposition vorangestellt?
Vielen Dank für die ausführliche Darstellung!

[@CryptographyForEverybody]

Hallo Michael Heynemann,
Die Indikatorgruppe identifiziert die zu nutzende Seite + Zeile. Für die erste Transposition werden die ersten fünf Wörter der Zeile als Schlüssel genommen. Für die zweite Transposition werden die letzten fünf Wörter der Zeile als Schlüssel genommen.
Viele Grüße,
Nils Kopal

[@ijfc6692]

amazing video sir, one question, can i contact you?

[@CryptographyForEverybody]

Hiho,
That depends :-). For helping with homework, studies, etc. I don't have time -- if I help any student, I would not have time for anything else. If you have a ciphertext etc. you can contact me. You'll find my contact info on www.kopaldev.de
Greetings,
nils