Locally Computable UOWHF with Linear Shrinkage

  • Benny Applebaum
  • Yoni Moses
Conference paper

DOI: 10.1007/978-3-642-38348-9_29

Part of the Lecture Notes in Computer Science book series (LNCS, volume 7881)
Cite this paper as:
Applebaum B., Moses Y. (2013) Locally Computable UOWHF with Linear Shrinkage. In: Johansson T., Nguyen P.Q. (eds) Advances in Cryptology – EUROCRYPT 2013. EUROCRYPT 2013. Lecture Notes in Computer Science, vol 7881. Springer, Berlin, Heidelberg


We study the problem of constructing locally computable Universal One-Way Hash Functions (UOWHFs) \(\mathcal{H}:\{0,1\}^n \rightarrow \{0,1\}^m\). A construction with constant output locality, where every bit of the output depends only on a constant number of bits of the input, was established by [Applebaum, Ishai, and Kushilevitz, SICOMP 2006]. However, this construction suffers from two limitations: (1) It can only achieve a sub-linear shrinkage of n − m = n1 − ε; and (2) It has a super-constant input locality, i.e., some inputs influence a large super-constant number of outputs. This leaves open the question of realizing UOWHFs with constant output locality and linear shrinkage of n − m = εn, or UOWHFs with constant input locality and minimal shrinkage of n − m = 1.

We settle both questions simultaneously by providing the first construction of UOWHFs with linear shrinkage, constant input locality, and constant output locality. Our construction is based on the one-wayness of “random” local functions – a variant of an assumption made by Goldreich (ECCC 2000). Using a transformation of [Ishai, Kushilevitz, Ostrovsky and Sahai, STOC 2008], our UOWHFs give rise to a digital signature scheme with a minimal additive complexity overhead: signing n-bit messages with security parameter κ takes only O(n + κ) time instead of O() as in typical constructions. Previously, such signatures were only known to exist under an exponential hardness assumption. As an additional contribution, we obtain new locally-computable hardness amplification procedures for UOWHFs that preserve linear shrinkage.

Copyright information

© International Association for Cryptologic Research 2013

Authors and Affiliations

  • Benny Applebaum
    • 1
  • Yoni Moses
    • 1
  1. 1.School of Electrical EngineeringTel-Aviv UniversityIsrael

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