I prize security solutions that protect people without slowing them down.
I think the Grand Challenge that a prize competition should solve is the problem of tracking mobile payments in places that only require a SIM card and an ID to open an account.
The benefits to solving this problem would be two-fold. First, it would cut down on the ability of individuals or groups to launder money that could go to support criminal enterprises. It’s likely that some users of mobile banking accounts are using false identification to set up their accounts or that they are transferring money for illegal reasons. An example of this type of mobile payment is M-Pesa, a service offered by Vodafone to users in Kenya and Tanzania.
Mobile payment systems like M-Pesa sprung up to fill a gap in the marketplace that was left open due to lack of access of large parts of the population. While traditional banks require some fluency with established institutions, mobile payments and banking are available to anyone with a mobile phone. To this end improving security around these payments ensures that access to these new institutions will remain available.
When the Grand Challenge is solved mobile payments are as secure and traceable as payments made through the means of traditional banking. It doesn't mean creating regulation, it means having visibility into patterns that allow outside groups to ascertain what a payment is for, but in a secure manner. The key is to come up with a solution that is not cumbersome to the point where it slows user experience but allows law enforcement to be able to track payments and make sure that these payments are not being used to fund illegal activities or organizations.