Blockchains have emerged as a promising instrument for
transparency and integrity in a decentralized fashion -- with an ever-increasing
interest from popular media, research, and policy communities. The blockchain
initially received wide attention as the underlying technology of Bitcoin proposed in 2009;
it has independently evolved since, thanks to its resilience, integrity, and transparency
properties, and spread to many other non-cryptocurrency applications. As Bitcoin suffers
from scalability and privacy issues that impede its wider adoption, many choose the
spectrum of permissioned or a combination of public and private blockchains. In a
public setting every transaction is published on a global ledger, which allows
small amounts of information (e.g., the identities of the participants in a single
transaction) to be amplified if statistical analysis is used to track user activities.
This limits the commercial usefulness of the current blockchain, and also harms individual privacy
as user behavior frequently reflects the pervasive assumption that Bitcoin is an anonymous system.
Ongoing research for public blockchains aims to alleviate privacy problems. In the meantime, private
ledgers offer improved privacy, but at the cost of security due to the reduction of the number of
participants. More importantly, decision-making entities of private ledgers are typically regulated
by a single trusted entity, which contrasts the fundamental security assumptions of open and
decentralized ledgers.
Research in the area has been focusing mainly on improving the proof-of-work, the
repurposing of mining energy, and denial-of-service attacks. With the Security on Blockchain
Workshop we propose to look at the major issues in adopting blockchains -- both permissioned and
permissionless models -- as a wide, secure and privacy preserving solution to contemporary
problems in various fields: financial, authentication, access control, medical applications,
fast data transactions, manufacturing processes, etc. We propose to focus on the critical
analysis of various implementations of blockchain solutions, and the security improvements
brought by technologies built on top of blockchains such as Sidechains, Confidential Transactions,
Hyperledger, Lightning Networks, and Smart Contracts, and their application to security and privacy
in the field.