tag for hand ciphers in the computer age

Question

I am interested in ciphers (and techniques for designing future ciphers) such that both (a) encryption can be done "by hand" without a computer, while also (b) the resulting ciphertext is (relatively) resistant to computer-aided cryptanalysis attacks.

What tag should I use for questions on crypto.stackexchange that discuss such ciphers?

• Some new tag, perhaps "modern-hand-cipher" or "modern-field-cipher" that covers exactly ciphers in this category?

• Some combination of tags, such as pen-and-paper to cover (a) and something like post-computer-cryptography to cover (b)? (Something analogous to post-quantum-cryptography ?)

For example, questions like Multi-round Transposition/Playfair as a secure hand cipher in the computer age ; Is there any strong enough pen-and-paper or mind cipher? ; Pen-and-paper one-way function for externally-anonymous survey ; Are there cryptographic hash functions that can be computed using only paper and pen without leaking any information about the plaintext? ; etc. all fall in this category I am interested in.

My understanding is that classical-cipher covers classical ciphers which are ciphers "historically used" before electronic computers were even invented. Almost all of the ciphers I am interested in were or will be designed as a reaction to computer-aided cryptanalysis, and therefore could not possibly have been "historically used" before electronic computers were invented.

Answer 1

Out of the existing tags, I'd say pen-and-paper is the best fit, and we do have several similar questions under that tag already, such as:

• Is there a secure cryptosystem that can be performed mentally?
• Are there cryptographic hash functions that can be computed using only paper and pen without leaking any information about the plaintext?
• Is there any strong enough pen-and-paper or mind cipher?
• Pen-and-paper one-way function for externally-anonymous survey
• Is there a cryptographic hash function that can be performed with pencil and paper?

Personally, I'd probably just tag your question as pen-and-paper, plus any tags for the specific kinds of operations you were asking about (e.g. encryption, hash, public-key, etc.).

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I'm not sure if we really need a new tag for computer-cryptanalysis-resistant hand ciphers, but if I did wish to create one, I might consider splitting pen-and-paper while doing so — its current scope is rather broad, covering both:

• classical hand ciphers (although those are usually tagged as classical-cipher, or with some more specific related tag, instead);

• modern non-computerized ciphers intended to resist (at least some) computer analysis; and

• toy ciphers intended for puzzles and educational purposes.

The current tag name also gives the impression of excluding purely mental ciphers, even though the tag wiki explicitly says those are in scope, so that might be an additional reason to rename the tag (or at least to add a tag synonym from mental-cipher).