When I need to access our school web portal I need to access it with my certificate (pfx). Since certificate needs to be installed in browser, I'm thinking (out of security reasons) to create a portable version of firefox. So I would buy a new usb stick, encrypt it's file system with TrueCrypt, so that every time I try to access it I have to enter my password. On it I would copy paste the newest versions of windows/linux firefox. To run FF from usb I would create a script with the startup switches like on this and this site in order to not mess up with any existing firefox profile and to not leave any trace on the pc where I would use my usb stick. Is this ok from the security point of view, have I missed something else?
Question is: Is this a secure way of having a portable FF? Since the later will be used only to access school portal from any machine in any network it needs to secure. By secure I mean: no one can misuse my login and/or certificate, I leave no browsing track/history on the host machine, my certificate can not be stolen, etc. In other words, what are possible security flaws in the setup I mentioned?
Jonathan has a few good points, however it all may look a bit exaggerating. What I'm dealing with are mostly home, free wifi and little corporate networks. So I don't need to be extra paranoid that content of my usb will be copied during usage, even though it could be. But there is a workaround even in this circumstance... I would create a bootable usb disk with a minimal linux distro, the only prerequisite here is that I can boot PC from usb and a DHCP network, and that should be all. In this case the only monitoring that can be done by admins is network traffic on routers, but they shouldn't get much info in my case, they can get the url I connect to and that's almost all, the traffic content is encrypted.
It's true, software needs to be up to date, so I would need to update FF at least once a month.
Are there any other security flaws in the idea I propose, I mean something like:
1) browser leaving tracks somewhere
2) type of encryption on usb
3) which file system to choose