Over any period of time, no probably not. If the algorithm is simple as "This was signed by an iphone" then you have a fleet of a billion+ iphones that all must remain secure and unbroken for the entire time this fleet of phones exist trends to unlikely. Given time and motivation all systems are broken.

A much harder to break system is one uses a secret only exists on each individual phone + the generic algorithm that iphones use, but this comes back to individuals being traced.