can I know what is the current situation regarding any kind of plugin/method for data masking?
I mean, if I would like to do it, what should be the best or suggest approach?
If you are meaning hiding some fields or documents depending on user rights, it's possible with the security plugin with a platinum license (commercial) or the 30 days trial which you can activate from Kibana.
no I would like to change field's value with, for instance, a hash.
I have already used the platinum feature "hide document/field" but in this situation I have to "change" the values inside fields.