Looks interesting. But I think I must be missing something.

Are the symmetric keys that are used to encrypt the private keys derived from a password, or not?

> This protocol overcomes this weakness by wrapping all key packets, encrypted with a key derived from a second high-entropy alphanumeric passphrase.

>

> The passphrase SHOULD be a random high-entropy uppercase alphanumeric string of 24 characters, generated from a cryptographically secure pseudo-random number generator (CSPRNG).

So do you seed the CSPRNG starting from something derived from a password? And if not, then how do you decrypt your private keys when you want to use them on a new device?