21–30 of 144 posts
For people interested in these kinds of things, there is a very interesting military manual on the internet archives which goes though all the various pre computer pen and paper ciphers and how to crack them. 1. https://archive.org/details/Fm3440.2BasicCryptAnalysis/mode/...
This is a familiar concept from reading about WW2 spy stuff (Between Silk and Cyanide, for example, which I highly recommend). But what REALLY intrigues me is the typeface of the letter with its upper-case 'E' used in place of 'e'. What's up with that?
Randomizing/obfuscating the letter case might buy you a little time, though I think it's something else entirely here.
Hasn’t known invariants been used to break modern encryption in TLs, etc? Like a SSH packet will always contain some known info, etc.
Note that it is equally dangerous to send paraphrased messages using the same key (which is called sending messages "in depth"). This was used to crack the Lorenz ("Tunny") cipher. Interestingly Bletchley Park hadn't gotten their hands on a Lorenz machine, they cracked it based on speculation. And it lead to the development of the first tube computer, Collosus (which influenced the ENIAC). Nowadays we use nonces to avoid sending messages in depth, but nonce reuse can be similarly disastrous for systems like AES-GCM. For example there have been Bitcoin hardware wallets that reused nonces, allowing the private key to be extracted & the Bitcoin stolen. (To be clear, cryptocurrencies and AES-GCM are completely different systems that have this one property in common.)
https://en.wikipedia.org/wiki/Cryptanalysis_of_the_Lorenz_ci...
https://www.youtube.com/watch?v=Ou_9ntYRzzw [Computerphile, 16m]
As an aside does anyone know why it's called "in depth?" I'm guessing that it's related to Bletchley Park's penchant for naming things after fish? But possibly also their techniques that involved arranging messages together and sliding a stencil over them to visually spot patterns (so they're sort of overlayed)? I tried some casual searching but it's a very generic phrase and so difficult to search. It's defined in the The 1944 Bletchley Park Cryptographic Dictionary but it doesn't give an etymology.
https://www.codesandciphers.org.uk/documents/cryptdict/crypt... [Page 28]
Earlier quoted context omitted.
Or ending it with the same salute involving the name of the leader, for that matter.
Isn't that why we have PFS now?
The term to google for more information about this would be Known plaintext attack.
Interesting. I liked the explanations in the accepted answer. This rule especially,“Never repeat in the clear the identical text of a message once sent in cryptographic form, or repeat in cryptographic form the text of a message once sent in the clear.” As a child I learned about codes from a library book. Fascinated with one-time pads, I convinced a friend to try a correspondence. We exchanged a few messages, and th…
>> the juice wasn’t worth the squeeze I recall that Ovaltine goes better with decoded messages.
Hasn’t known invariants been used to break modern encryption in TLs, etc? Like a SSH packet will always contain some known info, etc.