Comment on Is it possible to design a (pen and paper) cipher that is secure against government cryptanalysis for at least 10 years?

user224@lemmy.sdf.org ⁨16⁩ ⁨hours⁩ ago

• heavydust@sh.itjust.works ⁨16⁩ ⁨hours⁩ ago

  It’s a good algorithm but if you need to decode any message, you must get drunk and listen to creepy radio stations at 1AM in the forest or something.

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• IDKWhatUsernametoPutHereLolol@lemmy.dbzer0.com ⁨16⁩ ⁨hours⁩ ago

  Hmm yea cool, problem is, its not reusable. You have to generate new keys every time. Kinda not easy to constantly exchange new keys if you are… say a group of revolutionaries hiding from the government. 👀

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  • yoevli@lemmy.world ⁨16⁩ ⁨hours⁩ ago

    This is how all modern cryptography works. A deterministic cipher is functionally no different from pig Latin when it comes to actual security. A modern solution like public key cryptography is infinitely more secure. If you’re especially paranoid you can generate the cryptotext locally and send it by email; that would be infinitely more secure than anything you could achieve by hand.

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    • otacon239@lemmy.world ⁨13⁩ ⁨hours⁩ ago

      I would think mailing a flash drive with the key and sending the message electronically would be safer. One requires knowledge of the other.

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  • rowanthorpe@lemmy.ml ⁨8⁩ ⁨hours⁩ ago

    In-band periodic key-exchange. Pre-arrange that keys expire every X messages, and that the last (Xth) message is dedicated to sending the new key encrypted by the previous one.

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  • Nemo@slrpnk.net ⁨15⁩ ⁨hours⁩ ago

    That’s why you make a stack of them. Generate hundreds up-front and you don’t need to generate new every time.

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    • IDKWhatUsernametoPutHereLolol@lemmy.dbzer0.com ⁨15⁩ ⁨hours⁩ ago

      Hmm okay I was actually thinking of using this for journaling… so keeping a stack of OTP codes right next to my journal isn’y quite useful…

      gotta keep my evil plans for world domination a secret… MUAHAHAHAHA 😈

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      • SmoothOperator@lemmy.world ⁨6⁩ ⁨hours⁩ ago

        Hmm, you’re probably going to get a lot of answers assuming you wanted to do secure communication, not secure journaling. Different beasts I would think.

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  • m0darn@lemmy.ca ⁨15⁩ ⁨hours⁩ ago

    I’m certainly not an expert.

    But could you generate pads from mutually accessible data sources?

    Like use hit_me_baby_one_more_time_not_a_virus.mp3 appended with a password, as a seed in a pseudo random number generating algorithm, then do the same thing with another data source, repeat however many times, then XOR the generated numbers together, and use the result as a pad?

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    • pageflight@lemmy.world ⁨14⁩ ⁨hours⁩ ago

      Steganography may be interesting in that vein. Hiding data within larger images / sound files etc.

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    • ricecake@sh.itjust.works ⁨14⁩ ⁨hours⁩ ago

      That’s no longer a one time pad. That’s closer to a homebrew stream cipher with the weakness of having a key that you just hope no one notices.

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      • m0darn@lemmy.ca ⁨2⁩ ⁨hours⁩ ago

        Neat, yeah Wikipedia says steam cipher approximate one time pads but can also be completely insecure.

        I think it would take one hell of an effort to crack, it would be like 3MB encryption right? Or if they guessed the scheme they could try all mp3s ever torrented XOR’ed in every possible combination.

        Idk I think there’s something workable there but I only having a casual knowledge

        Also I think OP wanted pen and paper so maybe use a book instead digital files.

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