Presto Vivace's Journal: Security through obscurity?

Cryptography Breakthrough Could Make Software Unhackable

As a graduate student at the Massachusetts Institute of Technology in 1996, Amit Sahai was fascinated by the strange notion of a âoezero-knowledgeâ proof, a type of mathematical protocol for convincing someone that something is true without revealing any details of why it is true. As Sahai mulled over this counterintuitive concept, it led him to consider an even more daring notion: What if it were possible to mask the inner workings not just of a proof, but of a computer program, so that people could use the program without being able to figure out how it worked?

There must be something I am missing; because this sounds like proprietary software.