International Association
for Cryptologic Research

Constraint Programming for Cryptanalysis of Symmetric Encryption Schemes

• Location: LIMOS, Clermont-Ferrand, France
• Salary: 2000€
• Duration: 1 year
• Keywords: Cryptanalysis symmetric, constraint programming, SAT solving, ILP.
• Starting date: As soon as possible, when we have a good candidate; at least before October 2020.

Your Profile

• A PhD in Computer Science, Applied Mathematics, Cryptography or related field.
• Competitive research record in symmetric cryptography or in constraint programming.
• Commitment, team working and a critical mind.
• Good written and verbal communication skills in English are essential.

This post-doc is founded by the ANR project Decrypt started in January 2019.

Transforming a theoretical cryptanalysis into a SAT problem or into a set of linear constraints could be a hard and time-consuming task. Our aim is to use constraint programming (CP) to simplify the way the symmetric key attacks are modeled and thus to overpass existing cryptanalytic results. Preliminary studies are really encouraging.

Goal

The main goal is to identify schemes and attacks for which it is possible to use off-the-shelf CP, SAT or ILP approaches. To achieve this goal, the work will be divided into the following tasks.

1. Study symmetric encryption schemes and identify for several schemes the different components that are used in the scheme design.
2. Design CP, SAT, and ILP models for cryptanalytic problems on selected schemes. We will mainly focus on the following attacks: cube attacks, conditional cube attacks with division property, (related-key) differential and linear cryptanalysis, word-based division property / integral distinguisher.
3. Experimentally evaluate CP, SAT, and ILP solvers on the models designed in previous tasks, and compare these solvers with existing dedicated cryptanalysis approaches. Design of a tool to automate this task is one of the goals of the project.

Closing date for applications:

Contact: Pascal Lafourcade pascal.Lafourcade@uca.fr

More information: https://decrypt.limos.fr/post/postdoc-offer-limos/