Mihail Plesa

Security Software Engineer Special Telecommunications Service


Mihail Plesa works as a Security Software Engineer at Special Telecommunications Service. Mihail holds an MSc in Information Security from Military Technical Academy and he is currently pursuing a PhD in the field of applied cryptography at the Faculty of Mathematics and Informatics at the University of Bucharest. He is passionate about applying cryptography to solve problems ranging from basic confidentiality to privacy-preserving computation. Mihail has authored and co-authored research papers on topics like privacy-preserving machine learning or quantum cryptography.

Modern Contact Discovery. How not to betray your contacts

Whatsapp, Signal, Telegram or Messenger – We all have at least one messaging app installed on our smartphones. Whether they are e2e encrypted or not they all have a common client-server architecture. Besides this, they all require your contacts in order to function.

These apps needs to know which of your contacts stored in device use the same app to communicate. To do that, the app transmits your contacts to the server, which maintains a list of all the enrolled users. The server intersects its list with the list received from your phone and returns the result to the app. This is clearly a privacy problem that needs to be addressed.

In this talk, we will see different cryptographic protocols that solve the above problem. From the use of Intel SGX to the private set intersection protocols, we will review methods that can be deployed in order to protect your contacts. This talk will bring you to the edge of modern applied cryptography with topics like homomorphic encryption (HE), oblivious pseudorandom functions (OPRF) or secure multi-party computation (SMPC). Only through a good regulation followed by the implementation of modern and safe technological solutions, users of messaging apps can use fast communication and have their personal data protect at the same time.

Are you the next cyber security superstar?

If you are passionate about an information security topic or you have strong technical skills developing researches on your own, you should definitely Apply at Call for Papers. By submitting you will have the chance to showcase your work to +2000 attendees.

Other speakers joining this year

Alex “Jay” Balan

CISO Superbet Group

Bianca Lewis

CEO Girls Who Hack / Secure Open Vote

Giorgi Akhalaia

Associate Professor of ICT, Caucasus University; Scientific Cyber Security Association; Cyber Security Main Specialist at Caucasus Cyber Security Center - Regional Representative of Bit Sentinel Caucasus University

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They help us make this conference possible.


At Orange Business Services, we help our customers transform their industries, reimagine their services, create a positive impact and unleash the power of their data into an amazing and trusted resource.

With the dual expertise as a global operator coupled with the agility of an end-to-end integrator, Orange Business Services is a global network-native, digital services company. From connectivity, smart mobility services and the cloud to artificial intelligence (AI), analytics and cybersecurity, Orange Business Services helps businesses at every stage of their data management. Orange Business Services is represented in Romania by the business division of Orange Romania and helps large companies, SMEs and public authorities to transform their organizations through the use of technology and digital information.


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