The U.S. Army M-138 Strip Cipher

#cryptology, #cryptography, #cryptanalysis

In this video, we discuss and (crypt-)analyze the M-138 strip cipher system. First, we have a look how the M-138 works. After that, we encrypt and decrypt text with the M-138 component in CrypTool 2. Finally, we have a look at three different attacks, also implemented in an analyzer component in CrypTool 2: known-plaintext attack, partially known-plaintext attack, and the ciphertext-only attack.

The M-138 strip cipher was in use by the U.S. Army and the U.S. Navy. It was used in parallel to the M-94 cylinder cipher system. It was invented by Parker Hitt.

You find many details about the M-138 (aka the CSP-845) on this nice webpage here: https://maritime.org/tech/csp845.htm

Klaus Schmeh's blog article, which describes the cipher system, gives definitions of all strips, and contains some challenges is available here: https://scienceblogs.de/klausis-krypt...

If you are interested in learning the basics of cryptology, you should also have a look at our video series about basics of cryptology – also for beginners:    • Basics of Cryptology – Part 1 (Crypto...  

You may download the latest version of CrypTool 2 from here: https://www.cryptool.org/en/ct2/downl...