Abstract
Securely transferring tokenised assets between largely non-interoperable
blockchain networks is a great challenge to take on. Implementations
must coordinate transactions on multiple blockchain networks which have
inherently different characteristics and functionality. Moreover,
implementations must coordinate transactions in strict order, in an
atomic, synchronised way so that owners do not risk their assets
becoming lost, while also mitigating the age-old problem of “avoiding
double spend”. Several protocols for cross-network asset transfer, i.e.
the bridging of assets, exist, and several production bridge
implementations exist. However, frequent high-profile security breaches
have arguably given bridges a bad reputation. Therefore, there is a
clear need for standardised bridge protocols to re-establish trust. One
initiative for standardising cross-network bridges is the Secure Asset
Transfer Protocol (SATP) developed by the Internet Engineering Task
Force (IETF). This protocol establishes four distinctive phases for the
asset transfer process, driven by a standardised messaging cycle between
specialised bridge orchestration applications, known as gateways. In
this paper, we demonstrate a reference framework with functions needed
to implement SATP. We describe our implementation of this reference
framework, why SATP is unique and why SATP is likely to be an important
contribution to powering future bridges.