[crypto] Fwd: REMINDER: Program Crypto Working Group, March 24, 2017

[R. Hirschfeld]

-------- Original Message --------
Subject: REMINDER: Program Crypto Working Group, March 24, 2017
Date: 2017-03-22 11:48
 From: Secretariaat DM <secdm at tue.nl>
To: Secretariaat DM <secdm at tue.nl>

Dear all,

Just a reminder for the CWG-meeting on Friday, March 24, 2017.

With kind regards / Met vriendelijke groeten,
Anita Klooster
secretary of the section Discrete Mathematics

[cid:image001.gif at 01CB8FB5.88A9C0F0]

Dept. of Mathematics and Computer Science
MF 4.058
Office hours: Monday and Friday 08.30-12.30 h / Tuesday and Wednesday 
08.30-17.00 h
Telephone: +31 (0)40 2472254
Email: secdm at tue.nl<mailto:secdm at tue.nl>




CRYPTO WORKING GROUP


Friday, March 24, 2017
De Kargadoor (http://www.kargadoor.nl/utrecht/zaalverhuur.html)
Oudegracht 36, Utrecht



Program

10.45 - 11.30 hrs.    Joost Rijneveld (RU Nijmegen),
                                                 MQDSS signatures - 
construction

11.30 -  11.45 hrs.    Coffee / tea break


11.45 - 12.30 hrs.     Simona Samardjiska (RU Nijmegen),

                                                 MQDSS signatures - 
security

12.30 -  14.00 hrs.    Lunch break (lunch not included)


14.00 - 14.45 hrs.     Andreas Hülsing (TU/e),

                                                 Semantic Security and 
Indistinguishability in the Quantum World


14.45 - 15.00 hrs.     Coffee / tea break


15.00 - 15.45 hrs.     Christine van Vredendaal (TU/e),

                                                 Short generators without 
quantum computers: the case of multiquadratics




Abstract talks Joost Rijneveld & Simona Samardjiska:  MQDSS signatures - 
construction & security

We present MQDSS, the first signature scheme with a security reduction 
based on the problem of solving a multivariate system of quadratic 
equations (the MQ problem). In order to construct this scheme, we give a 
new security reduction for the Fiat-Shamir transform from a large class 
of 5-pass identification schemes and show that a previous attempt from 
the literature to obtain such a proof does not achieve the desired goal. 
We also give concrete parameters for MQDSS, provide a detailed security 
analysis showing that the resulting instantiation MQDSS-31-64 achieves 
128 bits of post-quantum security, and describe an optimized 
implementation.



Abstract talk Andreas Hülsing: Semantic Security and 
Indistinguishability in the Quantum World

At CRYPTO 2013, Boneh and Zhandry initiated the study of quantum-secure 
encryption. They proposed first indistinguishability definitions for the 
quantum world where the actual indistinguishability only holds for 
classical messages, and they provide arguments why it might be hard to 
achieve a stronger notion. In this work, we show that stronger notions 
are achievable, where the indistinguishability holds for quantum 
superpositions of messages. We investigate exhaustively the 
possibilities and subtle differences in defining such a quantum 
indistinguishability notion for symmetric-key encryption schemes.

We justify our stronger definition by showing its equivalence to novel 
quantum semantic-security notions that we introduce. Furthermore, we 
show that our new security definitions cannot be achieved by a large 
class of ciphers -- those which are quasi-preserving the message length. 
On the other hand, we provide a secure construction based on 
quantum-resistant pseudorandom permutations; this construction can be 
used as a generic transformation for turning a large class of encryption 
schemes into quantum indistinguishable and hence quantum semantically 
secure ones. Moreover, our construction is the first completely 
classical encryption scheme shown to be secure against an even stronger 
notion of indistinguishability, which was previously known to be 
achievable only by using quantum messages and arbitrary quantum 
encryption circuits.

This is joint work with Tommaso Gagliardoni (TU Darmstadt) and Christian 
Schaffner (UvA & CWI & QuSoft)