The asymmetric trust model lets each participant in a distributed system make its own trust assumptions about others, captured by an asymmetric quorum system. This contrasts with ordinary, symmetric quorum systems and threshold models, where trust assumptions are uniformly shared among participants. Fundamental problems like reliable broadcast and consensus are unsolvable in the asymmetric model if quorum systems satisfy only the classical properties of consistency and availability. Existing approaches overcome this by introducing stronger assumptions.

In recent work that was published at the OPODIS 2025 conference, CRYPTO team member Juan Villacis with coauthors Ignacio Amores Sesar from the University of Aarhus and Simon Holmgaard Kamp of Ruhr-Universität Bochum have shown that some of these assumptions are overly restrictive, so much so that they effectively eliminate the benefits of asymmetric trust. To address this, they have proposed a new approach to characterize asymmetric problems and, building upon it, they introduce algorithms for reliable broadcast and consensus that require weaker assumptions than previous solutions.