I understand www.lastpass.com uses AES256 algorithm as explained at : https://lastpass.com/support.php?cmd=showfaq&id=1096
AES utilizing 256-bit keys as well as PBKDF2: https://helpdesk.lastpass.com/account-settings/general/password-iterations-pbkdf2/
lastpass provides a bar to indicate password strength. Using 'asdf1111' as a password gives a moderate password strength :
Same password but uppercase 'ASDF' provides a stronger password (indicated by green bar) :
Why is uppercase text password stronger than lowercase ? I assume it's related to the AES256 algorithm implementation ?