New Approaches for Building Cryptographic Hash Functions

Cryptographic hash functions are a fundamental primitive, utilized in numerous security applications. With the recent attacks against many widely deployed hash functions (e.g., MD5, SHA-1), the search is on for new, secure hash functions to re-establish security of all the various protocols that rely on them. At the same time, hash functions like SHA-1 have seen expanded usage into applications that demand security properties not handled by traditional design approaches. In this talk, I'll discuss the traditional design setting for hash functions, investigate the insufficiency of proposed design approaches, and introduce our new approach, which enables building a single hash function with strong security guarantees for multiple applications. Beyond the traditional design setting, there exists another in which hash functions have dedicated-keys. I'll highlight some of the benefits and downsides of working in this setting and, as before, propose approaches for this setting that allow building hash functions secure in a broad sense. Joint work with Mihir Bellare