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

• m0darn@lemmy.ca ⁨1⁩ ⁨day⁩ 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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  • ricecake@sh.itjust.works ⁨13⁩ ⁨hours⁩ ago

    So, the size of the key doesn’t directly relate to the size of the cipher, which also doesn’t directly relate to security. AES is 128 bit , can have 128, 192, or 256 but keys and is currently not known to have any workable weaknesses.

    Largely a cipher isn’t weak if guessing the key is the only weakness, since every cipher is vulnerable to brute force. It’s weak if you can figure out the message without needing the key.

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    • m0darn@lemmy.ca ⁨10⁩ ⁨hours⁩ ago

      So how does generating a one time pad from mutually accessible data fit into this scheme. Is the pad the cipher or the key?

      If two people agreed that the pad would be the output of a particular pRNG given the 3rd paragraph of the second article on the third page of that day’s newspaper as a seed.

      The attack vector would be shortcomings in the pRNG I guess? Which could result in the possibility of some sort of statistical language attack?

      Or the attacker could guess the newspaper text & algorithm.

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