Paper 2015/031

Tight Parallel Repetition Theorems for Public-Coin Arguments using KL-divergence

Kai-Min Chung and Rafael Pass


We present a new and conceptually simpler proof of a tight parallel-repetition theorem for public-coin arguments (Pass-Venkitasubramaniam, STOC'07, Hastad et al, TCC'10, Chung-Liu, TCC'10). We follow the same proof framework as the previous non-tight parallel-repetition theorem of Hastad et al---which relied on *statistical distance* to measure the distance between experiments---and show that it can be made tight (and further simplied) if instead relying on *KL-divergence* as the distance between the experiments. We then show that our proof technique directly yields tight ``Chernoff-type'' parallel-repetition theorems (where one considers a ``threshold'' verifier that accepts iff the prover manages to convince a certain fraction of the parallel verifiers, as opposed to all of them) for any public-coin interactive argument; previously, tight results were only known for either constant-round protocols, or when the gap between the threshold and the original error-probability is a constant.

Available format(s)
Publication info
Published by the IACR in TCC 2015
parallel repetitionpublic coininteractive argumentscomputationally sound proofsKL divergence
Contact author(s)
kmchung @ iis sinica edu tw
2015-01-14: received
Short URL
Creative Commons Attribution


      author = {Kai-Min Chung and Rafael Pass},
      title = {Tight Parallel Repetition Theorems for Public-Coin Arguments using KL-divergence},
      howpublished = {Cryptology ePrint Archive, Paper 2015/031},
      year = {2015},
      note = {\url{}},
      url = {}
Note: In order to protect the privacy of readers, does not use cookies or embedded third party content.