Researching Heterogeneous Trust in Distributed Systems


Giuliano Losa

Publishing date

The Stellar Development Foundation (SDF) aims to support technological and scientific research that benefits the broader blockchain community by providing academic grants, offering hands-on collaboration with external researchers, and organizing workshops and conferences that bring researchers together to exchange ideas.

Last October, with the help of Christian Cachin (a well-known cryptographer from the University of Bern), we organized our first scientific research workshop: the Workshop on Heterogeneous Trust in Distributed Systems (HTDS). The workshop was held on October 26th in Princeton, NJ, following the Advances in Financial Technologies conference.

What is Heterogeneous Trust?

Distributed systems based on heterogeneous trust allow participants (e.g., blockchain validators) to make their own judgments about which other participants they trust. An example is the Stellar network, where each validator is free to pick which other validators it trusts the votes of when finalizing new blocks. Other systems based on heterogeneous trust include the XRP Ledger (which pioneered the idea in 2013), MobileCoin, and Anoma.

In contrast, systems like Ethereum do not support heterogeneous trust because validators have no choice but to follow the majority of staked ETH tokens. Similarly, in Bitcoin, validators must follow the majority of the hashing power.

The Unique Advantages

Compared to Proof-of-Work and Proof-of-Stake, blockchains based on heterogeneous trust have several key advantages, including:

  • They are not required to lock in capital, as in Proof-of-Stake, or to perform a lot of computation, as in Proof-of-Work.
  • They can harness real-world reputation to create sustainable, non-monetary incentives.
  • They can support issuer-enforced finality, which allows asset issuers to protect themselves from double redemptions in case of blockchain fork.

For more details, David’s talk at the workshop is an interesting take on those ideas.

A Developing Field

Nevertheless, the research community has focused primarily on Proof-of-Stake and Proof-of-Work, and many scientific questions about heterogeneous trust and its applications remain not only to be answered but also to be asked.

For example:

  • How do we implement consensus efficiently in the heterogeneous trust setting?
  • Can heterogeneous trust be used in a Proof-of-Stake setting?
  • What are the relationships between the different mathematical models proposed and their guarantees?
  • What are the possible applications beyond consensus protocols?
  • How do we adapt well-known cryptographic schemes (like threshold signatures) to the heterogeneous setting?

Heterogeneous trust has recently been gaining traction among researchers and it reached a critical mass where it made sense to organize an in-person workshop to spur research in this promising area.

The Results

The workshop attracted around 30 researchers, including ten speakers from top research universities (Stanford, UIUC, Duke, UC Riverside, Ohio State, and the University of Bern), as well as private companies (Heliax and Akamai). We hope that the ideas exchanged at the workshop will help develop heterogeneous trust as a valuable tool for the blockchain community to build safe, efficient, and reliable systems.

Recordings of the talks are available on Stellar Development Foundation YouTube, and you can find links to them on the workshop’s web page below.