RE: Create a new Steem Security Account with the command line wallet cli_wallet in the official docker image of steem
If you don't want to use the wallet, you can also use https://steeminvite.com The keys are only given to the person accepting the invite there, so it's equally safe. It also allows you to create them for free if you have enough RC.
RE: Create a new Steem Security Account with the command line wallet cli_wallet in the official docker image of steem