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I fail to see why one would want to use classical or pencil and paper tools for derivation. For anyone attacking your technique it will make no difference. An attacker with a modern computer will only brute force the part you memorized. Any key stretching done on pencil and paper will be a minor nuisance at best; anything done on paper will add no time at ...


7

If there is no upper bound on the length of the password to be used, the most common suggestion I know to create strong, easily-memorable (for some definition of "easy") password is diceware. The basic idea behind it is that it chooses each word via a roll of 5 d6's (e.g. each word has $6^5= 7765= 2^{12.92}\approx 2^{13}$ options). The entire ...


1

Judging by the use-case and solution it's really a pointless thing to do. GPG is used on a computer, so why would you want to create steps to generate the password manually if in the end you'd still need to write it via keyboard? If anything, it's a possible attack vector if the instructions get leaked e.g. via a co-located person or you forgetting it ...


1

Normally you would use a key derivation function, but since this question is about classical cryptography, I'll stick to the basics. An example of what I'll be doing below can be found on Wikipedia. I'll assume the user can remember multiple words of different lengths, for example ["london", "istanbul", "sheffield"]. You can use ...


1

A Ciphertext-only attack is what it sounds like, it's a type of attack model in which the attacker only knows the ciphertext (encrypted text) and has no knowledge of the plaintext (decrypted text). In practice though, usually the attacker has at least some knowledge of the plaintext, like the set of characters used or the language used. A one time pad can't ...


1

A mono-alphabetic substitution cipher simply replaces each symbol with another symbol, in a 1:1 fashion. So indeed you have 26 symbols or letters in the ciphertext. Now say you write down the ABC: ABCDEFGHIJKLMNOPQRSTUVWXYZ Each of these letters will need to be substituted by another one to go from plaintext to ciphertext. Lets use the same same symbols ...


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