Also, some thoughts on usability: - The key is huge and really unwieldy. Disguising it (for subtle key distribution) could be hard. Solitaire here has a bit of

Also, some thoughts on usability: - The key is huge and really unwieldy. Disguising it (for subtle key distribution) could be hard. Solitaire here has a bit of a better story (nobody looks twice at a pack of cards), but in general a good key-derivation function could help. (A bad key derivation function could totally compromise this scheme - which is why it’d be good to specify one!) - There’s no specifies incremental mode of operation (which is a useful property), which means that you’d have to manually break your ciphertext into blocks. It’d be good to specify an optimal block size. - The creator claims in other places (e.g. Reddit) that certain types of attacks don’t apply because this is a hand cipher. However a hand cipher doesn’t mean that both parties must be operating the cipher by hand! It seems like a common use-case would be for one party to have access to technology (e.g. a spymaster), in which case a bug could enable automated attacks on the system. What I do like about this cipher is the conceptual simplicity; I’m just bothered by the claim that it is a “strong” cipher without convincing evidence of that being true.