There is a solution. Too bad it's something which not many would like. The solution is to absolve all anonymity on the Internet, give everyone a biometric UID at birth, and be permanently associated with it. All interactions must go through a central server which ascertains that you are the correct person. Anyone found trying to commit identity fraud will be marked as treasonous, and given an extremely heavy penalty to dissuade such fraud.
Needless to say it would be the end of Anonymous, along a host of other issues. But you would remove the majority of identity spoofing.