International Association for Cryptologic Research

International Association
for Cryptologic Research


Double-block Hash-then-Sum: A Paradigm for Constructing BBB Secure PRF

Nilanjan Datta , Indian Institute of Technology, Kharagpur
Avijit Dutta , Indian Statistical Institute, Kolkata
Mridul Nandi , Indian Statistical Institute, Kolkata
Goutam Paul , Indian Statistical Institute, Kolkata
DOI: 10.13154/tosc.v2018.i3.36-92
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Presentation: Slides
Abstract: SUM-ECBC (Yasuda, CT-RSA 2010) is the first beyond birthday bound (BBB) secure block cipher based deterministic MAC. After this work, some more BBB secure deterministic MACs have been proposed, namely PMAC_Plus (Yasuda, CRYPTO 2011), 3kf9 (Zhang et al., ASIACRYPT 2012) and LightMAC_Plus (Naito, ASIACRYPT 2017). In this paper, we have abstracted out the inherent design principle of all these BBB secure MACs and present a generic design paradigm to construct a BBB secure pseudo random function, namely Double-block Hash-then- Sum or in short (DbHtS). A DbHtS construction, as the name implies, computes a double block hash on the message and then sum the encrypted output of the two hash blocks. Our result renders that if the underlying hash function meets certain security requirements (namely cover-free and block-wise universal advantage is low), DbHtS construction provides 2n/3-bit security. We demonstrate the applicability of our result by instantiating all the existing beyond birthday secure deterministic MACs (e.g., SUM-ECBC, PMAC_Plus, 3kf9, LightMAC_Plus) as well as a simple two-keyed variant for each of them and some algebraic hash based constructions.
Video from TOSC 2018
  title={Double-block Hash-then-Sum: A Paradigm for Constructing BBB Secure PRF},
  journal={IACR Transactions on Symmetric Cryptology},
  publisher={Ruhr-Universit├Ąt Bochum},
  volume={2018, Issue 3},
  author={Nilanjan Datta and Avijit Dutta and Mridul Nandi and Goutam Paul},