There is some interest in encryption schemes meant for humans to perform without computational aid. (Relevant questions here, here, and here.) People often cite the VIC pen-and-paper cipher, the Schneier Solitaire cipher, or more recently the LC4 cipher. These would be useful in the context of, say, two people using communication devices where one or both may be monitored.

I've seen these referred to as pen-and-paper ciphers, human-computable ciphers, and as low-tech ciphers. They've also been compared to historical ciphers.


I could not find any lit-reviews for these schemes. Generally, I'm wondering if this is a field, and how much it has been explored. More specifically, is there a name for this class of modern, strong, human-computable encryption schemes? Have there been any attempts at defining, describing or measuring what makes a cipher "human computable"?

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    $\begingroup$ AFAIK, this isn't really a field. It's of interest only to amateurs, computers are too widespread and too easy to use to make manual crypto worth the time. The closest you typically get is lightweight crypto, but even that is generally hard for humans to do by hand. Even existing manual crypo tends to be stretching the idea of "strong" quite a lot. $\endgroup$ Jul 11 '20 at 20:48
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    $\begingroup$ I think hand cipher or pen-an-paper cipher is as good as it gets when it comes to naming... $\endgroup$
    – Maarten Bodewes
    Jul 12 '20 at 10:13

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