Encryption of installation - 2 questions

[farinet at arcor.de]

1.
On a samsung whereto in installed lubuntu 13.10 (upgraded then by
do-release-upgrade to 14.04) i chose encryption and i got someting like
a 64 characters key. I wrote that down, as suggested. Do i understand
correctly that the encryption is somewhat "silently" done? And the need
of that key would only come up in case of some kind of "havary" of the hd?

In any case, unfortunately, i lost that key by moving inside my house
(very likely it ended in the poubelle :-( ). Now what should/could i do?
Actually, i do not have any problem, i can access all my data and
programs without any problem. But i would not like to have a bad
experience in the future if/when there is going something wrong.

2.
On the powerbook with a fresh lubuntu-ppc installation i chose
encryption as well. But there before logging in i'm asked the pswd i
gave in for the encription. Apparently there was no key generation (but
may be i missed that, since i had no control *DURING* the installation
(see my other msg)? Is that something new in 14.04 or is that a
difference due to the specific of ppc?