"Why wasn't it? Not for nefarious reasons, Gemmell says, but rather because developers simply weren't aware of the option to uses hashes as a proxy for email addresses. A translucent solution encrypts the sensitive data so that it is hidden even from the operator of the service, while enabling the two parties (parents, babysitters) to rendezvous. How many applications can benefit from translucency? We won't know until we start looking. The translucent approach doesn't lie along the path of least resistance, though. It takes creative thinking and hard work to craft applications that don't unnecessarily require users to disclose, or services to store, personal data. But if you can solve a problem in a translucent way, you should. We can all live without more of those headlines and apologies."