  The majority of smartphones either run iOS or Android operating systems. This
has created two distinct ecosystems largely controlled by Apple and Google -
they dictate which applications can run, how they run, and what kind of phone
resources they can access. Barring some exceptions in Android where different
phone manufacturers may have influence, users, developers, and governments are
left with little to no choice. Specifically, users need to entrust their
security and privacy to OS vendors and accept the functionality constraints
they impose. Given the wide use of Android and iOS, immediately leaving these
ecosystems is not practical, except in niche application areas. In this work,
we draw attention to the magnitude of this problem and why it is an undesirable
situation. As an alternative, we advocate the development of a new smartphone
architecture that securely transfers the control back to the users while
maintaining compatibility with the rich existing smartphone ecosystems. We
propose and analyze one such design based on advances in trusted execution
environments for ARM and RISC-V.
