When one generates keys using
ssh-keygen one gets prompted for a passphrase to encrypt the generated key with.
How strong should such a passphrase be, entropywise, to withstand a full-blown brute-force dictionary attack?
Also, are there any
ssh configuration settings that increase or reduce the advisable strength for the passphrase? (My understanding is that the slower the encryption algorithm used, the less entropy is required to put a passphrase encrypted with this algorithm beyond the reach of any feasible brute-force dictionary attack.)