Apple is opening small cracks in the iPhone's digital fortress as part of a regulatory clampdown in Europe that is striving to give consumers more choices — at the risk of creating new avenues for hackers to steal personal and financial information stored on the devices. The overhaul rolling out Thursday only in the Europe represents the biggest changes to the iPhone's App Store since Apple introduced the concept in 2008. Among other things, people in Europe can download iPhone apps from stores that aren't operated by Apple and are getting alternative ways to pay for in-app transactions.