On: Problems with Bruce Schneier's “Solitaire” (2001)

[brohee]

Well, I would say :

- practical (using a manageable amount of paper, and/or common items like a chess board, playing cards or dominoes...)

- fast enough (encrypt say at least one word per minute, pretty sure manual RC4 doesn't qualify here)

- secure against an adversary using computing ressources

- provides a way to easily store a strong key, a shuffled deck is pretty good at this

[pavel_lishin → brohee]

I'd add "plausibly deniable" as well - requiring either party to have a copy of "The Lil' Saboteur's Guide To Field Encryption" is probably bad for espionage.