Password strength

[Richard O'Neill]

On 10/21/2014 9:57 AM, kf4hcw wrote:
> A better solution is to get a good, strongly encrypted password 
> manager. (I like KeePass).
>
> Your master password gets you into your password manager.

  Wouldn't it be risky  to store a master password on a computer? Even 
if well encrypted it might still be hacked by the likes of sophisticated 
(Government) snoopers.
What about using multiplied combinations of large prime numbers to 
generate a key?