Rafail Ostrovsky

Encryption hides content, but anyone watching which addresses a program reads and writes can still draw conclusions. In a paper published in 1996, Goldreich and Ostrovsky showed how to run a program so that its access pattern looks the same regardless of input, at the cost of logarithmic overhead. The idea, oblivious RAM, got a second life once cloud services and secure enclaves like Intel SGX made the problem practical.

In 1997 he and Eyal Kushilevitz showed that private information retrieval works against a single server: you fetch a record from a database without the server learning which one. He is also a co-author of fuzzy extractors (2004), which make noisy data such as biometrics usable as cryptographic keys.