Trust-by-Design – Strong Security Arguments for Symmetric Key Cryptography

Project Information

SymTrust

Grant agreement ID: 101097056

DOI

10.3030/101097056

EC signature date 23 May 2023

Start date 1 September 2023

End date 31 August 2028

Funded under

• European Research Council (ERC)

Total cost

€ 2 485 000,00

EU contribution

€ 2 485 000,00

Coordinated by

RUHR-UNIVERSITAET BOCHUM
Germany

Periodic Reporting for period 1 - SymTrust (Trust-by-Design – Strong Security Arguments for Symmetric Key Cryptography)

Reporting period: 2023-09-01 to 2026-02-28

Summary of the context and overall objectives of the project

Being able to communicate privately and securely is essential in today’s digital world. From online banking and cloud storage to private messaging, our personal and professional lives depend on data being protected from unauthorized access.

Cryptography is the key technology that makes this possible. In particular, symmetric cryptography—the use of shared secret keys to encrypt and decrypt data—protects the vast majority of information that flows through the internet and is stored in digital systems. Its importance will only continue to grow as our reliance on digital infrastructure increases.

While symmetric cryptography has seen remarkable progress in terms of speed and efficiency, the same cannot be said for how we understand and guarantee its security. Many of today’s cryptographic security arguments rely on unproven or unrealistic assumptions, and even the attacks used to test them often rest on shaky ground.

This ERC Advanced Grant aims to change that. By developing cryptographic primitives whose security can be demonstrated from first principles, we aim to build the next generation of cryptographic tools: fast, efficient, and mathematically trustworthy foundations for secure digital communication.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The project is advancing steadily from foundational research toward practical, trustworthy cryptographic designs. During this period, we focused on understanding how the building blocks of cryptography interact, developing rigorous ways to argue about their security, and creating tools to analyze potential weaknesses.

Our work has led to several publications at top international conferences in cryptography. We clarified when certain cipher components are uniquely defined, resolving ambiguities that have long complicated security analyses. We established design principles that prevent specific structural weaknesses, ensuring that new ciphers can be provably resistant to entire classes of attacks. We also created a framework that connects abstract security proofs with practical attack methods, helping bridge the gap between theory and practice. Finally, we developed efficient tools to test and strengthen modern cipher designs that use modular addition, expanding our understanding of this important technique.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The advances described above all go beyond the state of the arts and provide a strong theoretical foundation for the next phase of the project, which will focus on developing practical design tools and complete trustworthy cryptographic systems.