http://vanillacoin.net/wiki/RPC/Commands

If a command requires parameters, like encryptwallet, it's just:
curl --data-binary '{"jsonrpc": "1.0", "id":"123", "method": "encryptwallet", "params": ["replacethispassword"] }' -H 'content-type: text/plain;' http://127.0.0.1:9195/

I am not a lawyer, please do not consider any of the following as legal advice.

There was a legal ruling that content hosts cannot be held responsible for the content that is uploaded by third parties. For example, it does not get YouTube in trouble when someone uploads illegal files to YouTube - as long as YouTube complies with legal requests to remove the files, then YouTube does not get in trouble, even though they were technically in possession of illegal files.

We expect the same rules to be enforced for Sia hosts. As all files are encrypted by default, it is between difficult and impossible for hosts to know whether or not they are accepting illegal files. Therefore, they cannot be held responsible for what is uploaded. If they receive takedown requests, they will have to follow through with the requests somehow. At the moment, we don't really have a button to help that happen, but if it becomes a problem in the future we will make sure that hosts have the tools required to remain compliant with the laws of their jurisdiction.

All decentralized technologies fall into a legal grey area. We will likely have to adapt as lawmakers start introducing regulations, but this is something that is not particular to Sia. All sharing economies are also in a regulatory grey area, such as Uber and Airbnb. I am not sure what the legal situation is going to look like in the future, but we are going to be conscious of the regulations and work hard to ensure that hosts can always be easily compliant with the laws of their jurisdiction.

I am not a lawyer, but I do not believe that running a Sia node is breaking the law, even if someone is using your Sia node for illegal activities. Dropbox, Amazon, and all cloud storage services have the same problem.