Michael Reichle

INSAIT / Cryptography

Michael
Reichle

Tenure-track faculty at INSAIT

Google Scholar dblp Email

I am a tenure-track faculty member at INSAIT, where I am building a research program in cryptography. We study the mathematical foundations of secure protocols, with a focus on signatures, encryption, and privacy.

Before joining INSAIT, I was a postdoctoral researcher at ETH Zurich with Dennis Hofheinz. I earned my PhD at École Normale Supérieure in Paris under the supervision of Brice Minaud and Michel Abdalla, and wrote my master's and bachelor's theses under Geoffroy Couteau. My doctoral work explored memory-efficient searchable encryption.

Explore the groupPublications

Updates

News

Selected work

Research highlights

All publications

01 / Privacy-preserving signatures

Blind signatures from minimal assumptions

Blind signatures let a user obtain a valid signature on a chosen message in a privacy-preserving manner. We develop new techniques for pairing-free blind signatures that minimize rounds and communication under minimal assumptions. Recent work with Chairattana-Apirom and Tessaro gives a three-move scheme based on the discrete logarithm assumption. It matches the three-move structure and underlying assumption of the seminal work by Pointcheval and Stern (JoC '00) while supporting unrestricted concurrent issuance, addressing a longstanding question in the area.

Three-Move Blind Signatures from DL

02 / Distributed trust

Threshold signatures with stronger security properties

Threshold signatures distribute control of a signing key among multiple parties, avoiding a single point of failure. We analyze such schemes in realistic security models, including adaptive security, where parties may be corrupted during protocol execution. Recent work with Katsumata and Takemure gives the first efficient post-quantum threshold-signature protocol with adaptive security. In particular, we show that the ubiquitous proof technique of rewinding is compatible with adaptive security, contrary to prior belief.

Adaptively Secure 5 Round Threshold Signatures from MLWE/MSIS and DL with Rewinding

03 / Encrypted data

Memory-efficient encrypted search

Encrypted multi-maps are a core building block for searchable encryption, allowing a client to retrieve values from outsourced encrypted data. Reducing random memory accesses improves performance on modern storage, but traditionally comes at the cost of increased query bandwidth. Recent work with Falzon and Gui gives the first schemes with optimal server storage to combine optimal search bandwidth with good page efficiency, reconciling bandwidth and memory efficiency in both static and dynamic settings.

Page-efficient Encrypted Multi-Maps: New Techniques for Optimal Search Bandwidth