Cryptology ePrint Archive: Report 2016/1087

CENC is Optimally Secure

Tetsu Iwata and Bart Mennink and Damian Vizár

Abstract: At FSE 2006, Iwata introduced the CENC encryption mode and proved its security up to 2^{2n/3} plaintext blocks processed in total. He conjectured optimal security up to a constant. In this brief note, we confirm this conjecture. Rather than proving it ourselves, we point out that the conjecture's proof follows as a corollary of Patarin's ``Theorem P_i xor P_j for any xi_max'' from 2010. This connection appears to have remained unnoticed, and the sole purpose of this brief note is to make the connection explicit.

Category / Keywords: secret-key cryptography / encryption mode, CENC, optimal secure

Date: received 19 Nov 2016, last revised 21 Nov 2016

Contact author: bart mennink at esat kuleuven be

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Note: updated references

Version: 20161121:151944 (All versions of this report)

Short URL: ia.cr/2016/1087

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