From what I read in your documentation:
Instead it is encrypted with a random 128-bit number that was picked when 1Password first created your Agile keychain. That 128-bit number is your true decryption key. This key, in turn, is encrypted using your master password.
The database is fully encrypted with this randomly generated key.
I'm not so much concern about the 128 bit length of the key than I am about it's randomness...
It's a known fact that computer aren't random machine; at the end of the day, it's gonna be a pseudo-random generated key.
Most PRNGs have a hard time having a full coverage with maintaining a good distribution.
This could definitively lead to weakness while attempting to hack the database.
Would it be possible to have more detail regarding the generation of this random key?
Regarding this 128b key, changing the master password will just reencrypt the key, the 128b key itself doesn't change, correct?
Assuming I'm willing to wait for the whole database to be re-encrypted with a new key, is there a way to request a regeneration of this key?