Authenticated Dictionaries with Cross-Incremental Proof (Dis)aggregation

Authenticated dictionaries (ADs) are a key building block of many cryptographic systems, such as transparency logs, distributed €le systems and cryptocurrencies. In this paper, we propose a new notion of cross-incremental proof (dis)aggregation for authenticated dictionaries, which enables aggregating multiple proofs with respect to di‚erent dictionaries into a single, succinct proof. Importantly, this aggregation can be done incrementally and can be later reversed via disaggregation. We give an ecient authenticated dictionary construction from hidden-order groups that achieves cross-incremental (dis)aggregation. Our construction also supports updating digests, updating (cross-)aggregated proofs and precomputing all proofs eciently. ‘is makes it ideal for stateless validation in cryptocurrencies with smart contracts. As an additional contribution, we give a second authenticated dictionary construction, which can be used in more malicious se‹ings where dictionary digests are adversarially-generated, but features only “one-hop” proof aggregation (with respect to the same digest). We add support for append-only proofs to this construction, which gives us an append-only authenticated dictionary (AAD) that can be used for transparency logs and, unlike previous AAD constructions, supports updating and aggregating proofs.