PhD Position F/M Security of ASCON and Lightweight Symmetric Primitives against Quantum Attackers

The Inria Centre at Rennes University is one of Inria's eight centres and has more than thirty research teams. The Inria Centre is a major and recognized player in the field of digital sciences. It is at the heart of a rich R&D and innovation ecosystem: highly innovative PMEs, large industrial groups, competitiveness clusters, research and higher education players, laboratories of excellence, technological research institute, etc.

This PhD position takes place within the ASCON-CAT project, which studies the resistance of the
ASCON cipher family against quantum attacks. ASCON-CAT aims at combining the expertise of its
members in cryptography, quantum computing and physical implementations to assess the security
levels of ASCON, and increase our understanding of the quantum security of symmetric cryptosystems
as a whole.

In 2018, the NIST launched a competition to select a new family of lightweight symmetric authenti-
cated encryption algorithms, therefore recognizing the importance that lightweight cryptography has
taken in industrial applications and research. After five years of competition, ASCON was selected
for standardization, and is now expected to become a major commercial standard. In parallel,
many other lightweight designs have been proposed throughout the competition and later on.

Mainstream symmetric primitives are widely believed to retain a good level of security against
hypothetical quantum adversaries. However, the past few years have shown that a lot can be
said about the quantum security of symmetric ciphers.The goal of ASCON-CAT is to tackle
this challenge on the high-profile target ASCON. Within this project, the goal of this PhD
will be to analyze the impact of quantum cryptanalysis families on ASCON and develop
dedicated attacks.

The ASCON-CAT project is a collaboration between Alice&Bob (Paris), Thales SIX (Gennevilliers)
and Inria Rennes.The PhD student will be jointly supervised with the cryptography group at
Thales SIX and is expected to collaborate regularly with the group.

The PhD candidate will study different categories of attacks and analyze their impact
on the ASCON cipher family and related targets. These categories will notably include:

• Linear and differential attacks
• Algebraic attacks (including Meet-in-the-middle attacks on hashing or Duplex encryption modes

It is expected that some of the observations made on ASCON and / or cryptanalysis techniques will
lead to results on other similar lightweight primitives.

More information on the research to be carried out in this project as well as relevant
bibliographic references are available on this document.

The PhD candidate will contribute to the research activities of the CAPSULE team
and collaborate with the ASCON-CAT project partners.

• Analyze existing families of attacks and build a bibliography of applicable attacks
• Design new attack algorithms and analyze their costs

The candidate will also communicate her/his work through publications and
communications in conferences, workshops or seminars.

The ideal candidate will have the following skills:

• A strong level in English for written and oral communication
• Relational skills (working in a team)
• A background in cryptography and / or algorithmics
• Programming skills in Python or other languages
• Notions of quantum computing

• Subsidized meals
• Partial reimbursement of public transport costs
• Possibility of teleworking (90 days per year) and flexible organization of working hours
• Partial payment of insurance costs

Monthly gross salary: 2100€ during the 2 1st years and 2200€ during the 3rd year.