Wll basically tht is the question on the latest Mist version, can I create a .json file wallet protected by a password (or not) just like I did using ethereumwallet.com?
The key file is called web3 secret storage (and version 3 is used today).
This format makes a password mandatory, but doesn't put a restriction on the password length. It can be zero. Or could be something really long.
There are various tools (wallets), which can export a V3 file. ethereumwallet.com (and I think myethereumwallet too) will use an empty password ('') for the unencrypted wallets.
On my local geth I've hit enter on both password fields and got a file with password of '':
$ geth account new Your new account is locked with a password. Please give a password. Do not forget this password. Passphrase: Repeat Passphrase:
Note: even with this, the file is still encrypted, albeit with the empty password. You need to remember it uses the empty password.
Let's clean up some confusion here.
- Mist is actually a browser. It is meant to be used to browse decentralized applications in the future. During the development process it only supports one DApp: the Ethereum Wallet DApp. see: github/ethereum/mist
- Ethereum Wallet DApp: Is the wallet software you refer to when saying "mist". That's okay, because it currently really almost is the same. The wallet DApp runs inside mist. see: github/ethereum/meteor-dapp-wallet
- Both mist and the wallet require a client (ethereum node) in the backend which could either be geth or eth (or really any other ethereum client). Currently, the mist browser includes all of them: mist browser, dapp wallet and a client for the backend. see: github/ethereum/go-ethereum for geth and github/ethereum/webthree-umbrella for eth.
Now that you understand that not Mist is the wallet, but the DApp provides the wallet functionality on top of (probably) geth, you can simply use the JSON-RPC API, the console and the keystore of geth. To backup your keys, check
~/.ethereum/keystore on Linux or checkout the other threads for other methods: