International Association for Cryptologic Research

International Association
for Cryptologic Research

CryptoDB

Kan Yasuda

Affiliation: NTT Secure Platform Laboratories, Japan

Publications

Year
Venue
Title
2018
CRYPTO
Encrypt or Decrypt? To Make a Single-Key Beyond Birthday Secure Nonce-Based MAC 📺
At CRYPTO 2016, Cogliati and Seurin have proposed a highly secure nonce-based MAC called Encrypted Wegman-Carter with Davies-Meyer ($$\textsf {EWCDM}$$EWCDM) construction, as $$\textsf {E}_{K_2}\bigl (\textsf {E}_{K_1}(N)\oplus N\oplus \textsf {H}_{K_h}(M)\bigr )$$EK2(EK1(N)⊕N⊕HKh(M)) for a nonce N and a message M. This construction achieves roughly $$2^{2n/3}$$22n/3 bit MAC security with the assumption that $$\textsf {E}$$E is a PRP secure n-bit block cipher and $$\textsf {H}$$H is an almost xor universal n-bit hash function. In this paper we propose Decrypted Wegman-Carter with Davies-Meyer ($$\textsf {DWCDM}$$DWCDM) construction, which is structurally very similar to its predecessor $$\textsf {EWCDM}$$EWCDM except that the outer encryption call is replaced by decryption. The biggest advantage of $$\textsf {DWCDM}$$DWCDM is that we can make a truly single key MAC: the two block cipher calls can use the same block cipher key $$K=K_1=K_2$$K=K1=K2. Moreover, we can derive the hash key as $$K_h=\textsf {E}_K(1)$$Kh=EK(1), as long as $$|K_h|=n$$|Kh|=n. Whether we use encryption or decryption in the outer layer makes a huge difference; using the decryption instead enables us to apply an extended version of the mirror theory by Patarin to the security analysis of the construction. $$\textsf {DWCDM}$$DWCDM is secure beyond the birthday bound, roughly up to $$2^{2n/3}$$22n/3 MAC queries and $$2^n$$2n verification queries against nonce-respecting adversaries. $$\textsf {DWCDM}$$DWCDM remains secure up to $$2^{n/2}$$2n/2 MAC queries and $$2^n$$2n verification queries against nonce-misusing adversaries.
2018
TCHES
Beetle Family of Lightweight and Secure Authenticated Encryption Ciphers 📺
This paper presents a lightweight, sponge-based authenticated encryption (AE) family called Beetle. When instantiated with the PHOTON permutation from CRYPTO 2011, Beetle achieves the smallest footprint—consuming only a few more than 600 LUTs on FPGA while maintaining 64-bit security. This figure is significantly smaller than all known lightweight AE candidates which consume more than 1,000 LUTs, including the latest COFB-AES from CHES 2017. In order to realize such small hardware implementation, we equip Beetle with an “extremely tight” bound of security. The trick is to use combined feedback to create a difference between the cipher text block and the rate part of the next feedback (in traditional sponge these two values are the same). Then we are able to show that Beetle is provably secure up to min{c − log r, b/2, r} bits, where b is the permutation size and r and c are parameters called rate and capacity, respectively. The tight security bound allows us to select the smallest security parameters, which in turn result in the smallest footprint.
2018
ASIACRYPT
Building Quantum-One-Way Functions from Block Ciphers: Davies-Meyer and Merkle-Damgård Constructions
Akinori Hosoyamada Kan Yasuda
We present hash functions that are almost optimally one-way in the quantum setting. Our hash functions are based on the Merkle-Damgård construction iterating a Davies-Meyer compression function, which is built from a block cipher. The quantum setting that we use is a natural extention of the classical ideal cipher model. Recent work has revealed that symmetric-key schemes using a block cipher or a public permutation, such as CBC-MAC or the Even-Mansour cipher, can get completely broken with quantum superposition attacks, in polynomial time of the block size. Since many of the popular schemes are built from a block cipher or a permutation, the recent findings motivate us to study such schemes that are provably secure in the quantum setting. Unfortunately, no such schemes are known, unless one relies on certain algebraic assumptions. In this paper we present hash constructions that are provably one-way in the quantum setting without algebraic assumptions, solely based on the assumption that the underlying block cipher is ideal. To do this, we reduce one-wayness to a problem of finding a fixed point and then bound its success probability with a distinguishing advantage. We develop a generic tool that helps us prove indistinguishability of two quantum oracle distributions.
2016
EUROCRYPT
2016
FSE
2016
FSE
2014
EPRINT
2014
ASIACRYPT
2014
FSE
2014
FSE
2013
ASIACRYPT
2011
FSE
2011
CRYPTO
2009
EUROCRYPT
2009
FSE
2008
FSE
2008
ASIACRYPT
2007
ASIACRYPT

Program Committees

FSE 2020
FSE 2017
Asiacrypt 2014
FSE 2010
Asiacrypt 2010