Blockchain enables the creation of distributed ledgers as a type of database that is shared, replicated, and synchronized among the members of a network. In this paper we analyze how distributed ledgers can be used for empowering end-users to self-manage their own data, enabling third parties to access those data under a cryptographic management model. We propose a use case where both blockchain and smart contracts are employed by using cryptographic technology to enable user empowerment of data management in AmI. Finally, we analyze strengths and weaknesses of the proposed scenario.