Adaptively-secure Multiparty Non-interactive Key Exchange
- Author(s): Hanumantha Rao, Vanishree;
- Advisor(s): Sahai, Amit;
- et al.
Non-interactive key exchange (NIKE) is a fundamental notion in Cryptography.
This notion was introduced by Diffie and Hellman in 1976. They proposed the
well-known 2-party NIKE protocol and left open the generic question of whether
NIKE could be realized in the multiparty setting. NIKE has since then been an
active area of research with an ultimate goal of obtaining best possible security in
the multiparty setting. Although this has evaded researchers for many decades,
advancements have been made through relaxations in multiple directions such as
restricting to 3-parties, static/semi-static model (where the adversary needs to
commit to the set of parties he wishes to be challenged upon ahead of time),
random-oracle model, allowing initial setup, etc.
This dissertation provides a solution to the open question: it provides a multiparty
NIKE protocol that is adaptively secure with no setup and in the standard
The solution employs novel techniques of using indistinguishability obfuscation,
which are interesting in their own right and which seem promising in finding
wider applications in other settings. One such technique pertains overcoming the
somewhat inherent drawback of non-adaptivity of the puncturing technique introduced by Sahai and Waters [STOC'14].