angry tapir writes: "A group of Microsoft researchers want to make smartphone security less intrusive. To do so, they built and tested a prototype system that continuously assesses confidence in the identity of the person using the handset. They employed biometric identification, typical and atypical user behaviour, other device proximity (through wireless technology such as Bluetooth), environment sensors and a software system that permits more or less access to a phone's functions based on whether it's likely that the authorised person is using the phone (full paper here [PDF]). The result: You don't have to enter your phone's PIN or password nearly as often, but there was no reduction in security during tests. The two most interesting things are the confidence system (which can increase or decrease confidence in a user's identity) and the multi-modal authentication system, which employs the full array of sensors present in many smartphones to determine identity."