The implications of providing such a feature have been discussed since long time in
the ethereum community and the EIP712 covers (among other things) this scenario.
Currently AFAIK, there is no AEX or default standard for such feature in the Aeternity community,
so I have implemented it porting the EIP712 recommendations to Aeternity using the forumla:
'\x19Aeternity Signed Message:\n' + str(len(message)) + message
Before merging I would like to hear if there are any comments to be made regarding this functionality
What do you think?