Blockchains and distributed ledger technologies are perhaps most notable for underpinning the cryptocurrency Bitcoin, amongst many others. However, of late, researchers in academia and industry have recognized blockchain infrastructure as a ‘general purpose technology’ with the potential to fundamentally transform the way distributed networks of peers can trust, transact, collaborate, organize and identify themselves.

Swan (2014) proposed three evolutions of blockchain. Blockchain 1.0 describes Bitcoin and other cryptocurrencies, and concerns the secure transaction of digital property. Blockchain 2.0 describes the development of decentralized economies and financial instruments, based on the implementation of ‘smart contracts’: self-executing code that is immutably embedded in a blockchain. The most well-known example of a Blockchain 2.0 technology is ‘Ethereum’. First developed in 2015, Ethereum proposes to build a decentralized internet, and supports the deployment of ‘decentralized applications’ (‘dapps’) on its blockchain platform. Beyond this, Blockchain 3.0 articulates decentralized principles of governance and justice throughout society, underpinned by the diffusion of blockchain technology.

Beyond Bitcoin, which continues its volatile rise in value, potential applications of Blockchain 2.0 are being envisioned in all manner of domains. Many of these domains, such as currency, identity and data management are longstanding areas of interest for the CHI community. But throughout, there are more fundamental interactional, infrastructural and societal issues at stake, which warrant the attention of HCI researchers and practitioners, and which this workshop will surface and address.

While previous work in HCI and related fields has addressed, in particular, the users and infrastructure of Bitcoin efforts to address the socio-political, technical, economic and cultural implications of blockchain more fundamentally are only emerging. Lustig and Nardi (2015) point to the Bitcoin protocol as a case of ‘algorithmic authority’. Nissen et al.’s DIS 2017 workshop specifically considered the potential of Distributed Autonomous Organizations (DAO’s) in mediating new value transactions. Jabbar and Bjørn (2017) point to the wider infrastructure and necessary materiality of blockchain services and applications. This recent work frequently highlights the fundamental human challenges requisite in interactions with blockchain and distributed ledger technology.

This workshop seeks to foster such constructive and critical perspectives, and identify specific areas of interest and relevance for HCI. These may include:

Transactions and Financialization

Transactions are a basic component of how people interact with a blockchain. This feature is most evident in the exchange of a new forms of currency or tokens, which could be paid, or rewarded on the basis of any kind of definable interaction – such as viewing an advert (, entering a chat group (, or upvoting a comment ( These may provide the basis for a metered internet, but more fundamentally, Iaconesi [3] argues that reducing such interactions to transactions, risks a ‘financialization’ of everyday life. This view begs questions about the lived experience of life on the ledger.

Designing for Privacy and Trust

Blockchain technologies potential reframe existing privacy challenges, and implicate new models of trust. Rather than needing to trust the actors or mediators in an exchange, users are expected to trust a technical protocol. Werbach (2017) describes this as ‘trustless trust’. The promise of blockchain technologies is in supporting new forms of collaboration and privacy between actors who previously could not trust each other. However, Sas and Khairrudin’s (2017) studies of cryptocurrency exchanges show that even while the underlying Bitcoin protocol may be secure, interactions with blockchain applications can create new mediators and require new frameworks for trust and privacy. In particular, we may ask how privacy rights gained through GDPR, or the ‘right to be forgotten’, can be accommodated with DLT’s.

Decentralized Economies

By underpinning peer-to-peer economies, blockchain technologies can foster the self-organization of crowds and publics. These are issues of longstanding and contemporary interest to HCI, with the potential for both empowerment and exploitation. The opportunities and challenges in displacing existing mediators is apparent, for example, in the context of international development. Currently, large NGOs, governments and corporations mediate the centralized delivery of much international aid. Blockchains might offer greater transparency, and more direct relationships and economies between donors and recipients. However, the actual work of aid organizations on the ground is complex and perhaps not so easily abstracted.

DAO’s and Algorithmic Governance

For some, the prospect of breaking up, or radically reforming existing centralized models of governance and exchange is the central promise of blockchain. However, as a socio-technical infrastructure, blockchains replace existing mediators with new forms of algorithmic governance. This especially extends to networks of things that can enact agency through smart contracts, and function as distributed autonomous organizations (DAO’s). There are fundamental questions to be asked about how these new forms of governance are constructed, understood and made accountable.