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On December 5th, Lefteris presented "CALYPSO:
Sharing of Private Data over Blockchains" at Bitcoin Wednesday in Amsterdam. He discussed the two main CALYPSO concepts: on-chain secrets and skipchain-based identity and access management.

CALYPSO, the first fully-decentralized, auditable access-control framework for secure blockchain-based data-sharing which builds upon two abstractions. First, on-chain secrets enable collective management of (verifiably shared) secrets under a Byzantine adversary where an access-control blockchain enforces user-specific access rules and a secret-management cothority administrates encrypted data. Second, skipchain-based identity and access management enables efficient administration of dynamic, sovereign identities and access policies and, in particular, permits clients to maintain long-term relationships with respect to evolving user identities thanks to the trust-delegating forward links of skipchains. The evaluation of our CALYPSO implementation shows that the latency for processing read and write requests scales linearly with the number of secret-management trustees and is in the range of 0.2 to 8 seconds for 16 to 128 trustees. Lastly, three specific deployments of CALYPSO illustrate its feasibility and applicability to data-sharing problems faced by real-world organizations.



Lefteris, Philipp and Linus presented their work related to PERSONHOOD.ONLINE at the recent Master Blockchain Workshop in Amsterdam on November 17-18 2018, where a a thorough look at layer I scaling solutions for blockchains was provided by multiple experts.



After years of research on scalable blockchain systems and Proof-of-Personhood mechanisms we are proud to launch the PERSONHOOD.ONLINE website to highlight developments by EPFL DEDIS around the theme of a more human-centric digital society.

PERSONHOOD.ONLINE is an EPFL DEDIS project focused on developing next-generation blockchain and cryptographic technologies to enable a people-centric digital society where online participants can be trusted to be real human beings while remaining anonymous but accountable. Through those technologies, we aim at fostering democracy and creating equal opportunities in the real world by restoring trust on the internet and reshaping social networks and applications.