Aren't shorter keys more prone to collisions and bruteforce attacks? Given the same cipher, more or less, yes. Between ciphers, though, key-lengths are less re

Aren't shorter keys more prone to collisions and bruteforce attacks? Given the same cipher, more or less, yes. Between ciphers, though, key-lengths are less relevant, and the differences in those ciphers become more so. EDIT: Think of it in terms of Shannon Entropy: because RSA requires a pair of primes, the keyspace is so much sparser — that is to say, more "predictable" (if, granted, at a mostly theoretical level) — so keys need to be that much larger to be secure. Contrarily, with ED25519, keys can be smaller, because the keyspace is denser. (Or am I just talking out my ass here?) EDIT 2: s/smaller/sparser/, s/bigger/denser/, regarding keyspaces. Thanks, 'lisper!