Encrypted Davies-Meyer and Its Dual: Towards Optimal Security Using Mirror Theory PDF
Preview Encrypted Davies-Meyer and Its Dual: Towards Optimal Security Using Mirror Theory
Encrypted Davies-Meyer and Its Dual: Towards Optimal Security Using Mirror Theory Bart Mennink, Samuel Neves Radboud University (The Netherlands), University of Coimbra (Portugal) CRYPTO 2017 August 24, 2017 1/23 Luby-Racko(cid:27) / Feistel Now Introduction PRP PRF 2/23 Now Introduction Luby-Racko(cid:27) / Feistel PRP PRF 2/23 Introduction Luby-Racko(cid:27) / Feistel PRP PRF Now 2/23 Xor of Single Permutation p 0(cid:107)· x p y 1(cid:107)· • Single permutation using domain separation Xor of Permutations Xor of Permutations p 1 x p y 2 • First suggested by Bellare et al. [BKR98] • Secure up to 2n queries [BI99,Luc00,Pat08] • Application: CENC, SCT 3/23 Xor of Permutations Xor of Permutations Xor of Single Permutation p p 1 0(cid:107)· x p y x p y 2 1(cid:107)· • First suggested by Bellare et al. [BKR98] • Secure up to 2n queries [BI99,Luc00,Pat08] • Application: CENC, SCT • Single permutation using domain separation 3/23 EWCDM ν p1 p2 t h(m) • Message authentication using EWCDM Encrypted (Wegman-Carter) Davies-Meyer EDM x p p y 1 2 • By Cogliati and Seurin [CS16] • Secure up to 22n/3 queries • Conjecture: optimal 2n security 4/23 Encrypted (Wegman-Carter) Davies-Meyer EDM EWCDM x p1 p2 y ν p1 p2 t h(m) • By Cogliati and Seurin [CS16] • Secure up to 22n/3 queries • Conjecture: optimal 2n security • Message authentication using EWCDM 4/23 EDMD x p p y 1 2 → − − −− Earlierproposal EWCDMDremovedafter observationbyNandi EDMD (cid:22)(cid:22) 2n Backbone of analysis: mirror theory Our Contribution EDM and EWCDM (dashed) x p p y 1 2 h(m) scheme [CS16] now EDM 22n/3 2n/n EWCDM 22n/3 2n/n 5/23 → − − −− Earlierproposal EWCDMDremovedafter observationbyNandi Backbone of analysis: mirror theory Our Contribution EDM and EWCDM (dashed) EDMD x p p y x p p y 1 2 1 2 h(m) scheme [CS16] now EDM 22n/3 2n/n EWCDM 22n/3 2n/n EDMD (cid:22)(cid:22) 2n 5/23
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