When it comes to truly secure, crossplatform, password management and file encryption solutions I have two go to options; LastPass and TrueCrypt. Since these are not available in the Ubuntu repositories, installing these on Linux is a manual process. The following will make installing both of these products a snap.
Install TrueCrypt
Using your browser navigate to the downloads page of the TrueCrypt website and download the version appropriate for your system. Install TrueCrypt using the following commands.
cd ~/Downloads
tar -zxvf truecrypt-7.1a-linux-x64.tar.gz
sudo chmod +x truecrypt-7.1a-setup-x64 && ./truecrypt-7.1a-setup-x64
Install LastPass
Using your browser navigate to the downloads page of the LastPass website and download the version appropriate for your system. Install LastPass using the following commands.
cd ~/Downloads
tar -zxjf lplinux.tar.bz2 # Edit corrected tar arguments, thank you Gavin Coopertar -vxjf lplinux.tar.bz2
sudo chmod +x install_lastpass.sh && ./install_lastpass.sh
# Restart your browser