Sign Messages for user authorization

We are trying to implement user authorization with our server. We want to achieve this by signing the message on the client with user wallet and verify on the backend if this is the same user.
There couple of questions:

  1. We are using the decentraland functionality for sign messages: @dcl/crypto-scene-utils or @decentraland/EthereumController. By executing the signMessage() method, we can see that there is request in wallet (Metamask) for sign. But the message displays in Hex. Is there is a way to display the real message?
  2. We are trying to verify this message in backend with Web3j lib. But it is not working (while executing the same code on signature and message generated by react appl with web3js - it is working good). Is there any way to do? Any examples? How possible to verify the message signed by decentraland sdk? Or, maybe, how to use the web3js lib in sdk?