Strength of Filevault encryption

[dpo]

Is it reasonable to assume that the strength of Filevault 2 encryption is to some degree determined by how strong a password you use?

In which case, if I started out with a fairly simple password on my account and ran a Filevault encryption, is there any way to beef it up by making the password more complex, or do I have to unencrypt, improve password, re-encrypt?

Cheers..

 

[Weaselboy]

Yes, your assumption is correct. If someone guesses your login password, that will decrypt FV2 and allow full access.

You can just change your login password to something stronger and you are good to go.

No need to repeat the encryption. Also, your previous recovery key (that 24 character one when you first encrypted) stays the same.

 

[dpo]

When I come to sell my Mac, is it sufficient simply to do a clean install of Lion (thereby turning off/overwriting the previously encrypted volume)?

Is there anything else I can do to zero out the blocks on the drive, or verify that my data is definitely gone?

 

[Weaselboy]

When I come to sell my Mac, is it sufficient simply to do a clean install of Lion (thereby turning off/overwriting the previously encrypted volume)?

Is there anything else I can do to zero out the blocks on the drive, or verify that my data is definitely gone?

That would be all you need to do. Just leave FV2 on and when you do the new install reformat the drive and reinstall.