International Association for Cryptologic Research

International Association
for Cryptologic Research


Zero-Communication Reductions

Varun Narayanan
Manoj Prabhakaran
Vinod Prabhakaran
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Abstract: We introduce a new primitive in information-theoretic cryptography, namely zero-communication reductions (ZCR), with different levels of security. We relate ZCR to several other important primitives, and obtain new results on upper and lower bounds. In particular, we obtain new upper bounds for PSM, CDS and OT complexity of functions, which are exponential in the information complexity of the functions. These upper bounds complement the results of Beimel et al. (2014) which broke the circuit-complexity barrier for ``high complexity'' functions; our results break the barrier of input size for ``low complexity'' functions. We also show that lower bounds on secure ZCR can be used to establish lower bounds for OT-complexity. We recover the known (linear) lower bounds on OT-complexity by Beimal and Malkin (2004) via this new route. We also formulate the lower bound problem for secure ZCR in purely linear-algebraic terms, by defining the invertible rank of a matrix. We present an Invertible Rank Conjecture, proving which will establish super-linear lower bounds for OT-complexity (and if accompanied by an explicit construction, will provide explicit functions with super-linear circuit lower bounds).
Video from TCC 2020
  title={Zero-Communication Reductions},
  booktitle={Theory of Cryptography},
  author={Varun Narayanan and Manoj Prabhakaran and Vinod Prabhakaran},