This paper shows how to adapt existing non-Byzantine CRDT algorithms and make them Byzantine fault-tolerant. The proposed scheme can tolerate any number of Byzantine nodes (making it immune to Sybil attacks), guarantees Strong Eventual Consistency, and requires only modest changes to existing CRDT algorithms.

The approach is based on a graph of hashes which looks remarkably similar to a Git commit history. Sadly this has the downside that the history has to be retained in its entirety for the structure to be self-validating.