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Lefteris Kokoris-Kogias, from Calypso Technology

Lefteris Kokoris-Kogias of Switzerland’s EPFL

Sharing of Private Data over Blockchains

As the popularity of social media like Facebook has grown, it has become critical to find more secure ways to share our personal information with others.  The Cambridge Analytica scandal of March 2018 revealed how one company exploited the personal information of millions of Facebook users in order to sway voter opinion in the 2016 US presidential election.

Most blockchain-based apps are designed to share data that can be verified between individuals without offering a way to protect this info.  With Calypso, Lefteris Kokoris-Kogias of Switzerland’s EPFL has taken on the challenge of sharing confidential information securely via a distributed ledger.  During Bitcoin Wednesday on 5 December, 2018, he will present his solution to this problem.

Calypso is a fully decentralized, auditable access-control framework for secure data sharing.  Current blockchain-based systems do not support this functionality or, if they do, tend to rely on semi-centralized solutions that provide storage and access control for sensitive data off chain.  During his presentation Lefteris will discuss the feasibility of Calypso through three actual deployments that illustrate its usefulness for data sharing problems faced by real-world organizations.

Lefteris writes:

Calypso builds on two concepts: On-chain secrets and skipchain-based identity and access management.

First, secrets can be collectively managed and verifiably shared on chain.  Second, identity and access management enables long-term relationships with dynamic sovereign identities.

A skipchain, a data structure that allows information to be read from non-sequential blocks, supports these features and allows us to securely and very efficiently update access to the information we need to protect.

Our implementation of Calypso also appears to be very scalable; it has a latency in the range of 0.2 – 8 seconds for 16 – 128 trustees.

Lefteris is an expert in decentralized trust systems that are designed to increase the robustness and transparency of today’s Internet.  He has twice been awarded the IBM PhD Fellowship, the EPFL EDIC Fellowship, and the NTUA Thomaidio Award, and his work has been published in top tier computer science conferences like USENIX Security and IEEE Security and Privacy.

He is specialized in scalable blockchain systems, bias-resistant decentralised randomness generation, secure software update dispersion, novel applications of threshold cryptography and distributed consensus.  He is a PhD researcher at EPFL where he is advised by Professor Bryan Ford.

Lefteris Kokoris-Kogias of Switzerland’s EPFL