Since we now have a subforum for Electrum, I am rewriting here what I already said in other threads. I hope it's more visible in its own thread.
It is not safe to use a portable version of Electrum on an insecure computer!
Don't get me wrong: I am not saying that a portable build is by itself more dangerous than a non-portable version.
However, a portable version does not bring anything more in terms of security. It does not protect you from the computer you are using.
In addition, portable builds encourage dangerous behaviour, because they make it very easy to use your wallet on third party computers, that might be infected with viruses and keyloggers.
I was never enthusiastic about distributing portable versions of Electrum.
I did it because the demand for portable versions was so high that portable builds distributed by third parties were getting popular.
That's the only reason why I accepted to distribute portable builds: I do this in order to avoid an even worse situation.
I like very much Electrum but generally I disagree with you.
Surely everything could be used wrong and can create false security feelings.
But generally I consider a portable version more secure and more flexible than an installed one. (if works)
Let us see some concrete examples:
- Skype released a couple of years ago a version which had a reduced functionality than the old one. Once installed the new one it was impossible to put again the old version. It couldn't be found anywhere on the internet. With portable versions you start the new version and if you don't like it then you use again the old one and you can switch as you wish.
- I use Electrum 7.1 portable and it works. Now I downloaded Electrum 8.0 and by starting is giving to me some messages that my wallet doesn't work. Should make a new wallet or repair the old ? I didn't liked any of this options and I started 7.1 again. Otherwise if not backup-ed and installed over who knows what happened with the content of the old wallet.
- I could use Electrum on a computer shared with others. To install it would require administrator priviledges. To ask from the administrator would attract attention on it and could put on risk the coins.
- Electrum is installed on a shared computer. Even in this case I would use my own portable version because on the installed one could be a spyware. Of course a key-logger would be anyway there if installed but that mostly can be fooled with onscreen-keyboard.
- I can have a laptop which is not full-encrypted. A Trucrypt container can be put in the dropbox order(backup is also solved instantly) and there could be not only the wallet but the portable application also. If I have the application outside of the container somebody could boot the laptop from a CD(or access it from a hacked dropbox account) and install a spyware on the application. So I have more security if the application is also inside of the container.