Multi-Input Functional Encryption: Abhishek Jain, BU/MIT (BUSec Seminar)

Starts:
10:00 am on Wednesday, November 20, 2013
Ends:
11:00 am on Wednesday, November 20, 2013
Location:
MCS 137
Abstract: We introduce the problem of Multi-Input Functional Encryption, where a secret key K_f can correspond to an n-ary function f that takes multiple ciphertexts as input. Multi-input functional encryption is a general tool for computing on encrypting data which allows for mining aggregate information from several different data sources (rather than just a single source as in ordinary functional encryption). We show wide applications of this primitive to running SQL queries over encrypted database, non-interactive differentially private data release, delegation of computation, etc. We formulate both indistinguishability-based and simulation-based definitions of security for this notion, and show close connections with indistinguishability and virtual black-box definitions of obfuscation. Assuming indistinguishability obfuscation for circuits, we present constructions achieving indistinguishability security as well as simulation-based security (in those settings where simulation security is possible). Assuming differing-inputs obfuscation [Barak et al., FOCS'01], we also provide a construction with similar security guarantees as above, but where the keys and ciphertexts are compact. If time permits, I will also discuss how to extend functional encryption (both single-input and multi-input) to handle randomized functionalities, which opens new exciting applications. Based on joint work with Shafi Goldwasser, Vipul Goyal and Amit Sahai.