CFCS Invited Talks

Mutator Set: a Scalable Cryptographically Authenticated Data Structure for Private UTXOs

  • Dr. Alan Szepieniec, Neptune
  • Time: 2023-11-17 16:00
  • Host: Dr. Tianren Liu
  • Venue: Room 204, Courtyard No.5, Jingyuan


A mutator set is a cryptographic data structure for efficiently authenticating operations on large sets, similar to a Merkle tree but with new features:
-you can add items to the set;
-you can remove items from the set;
-you cannot link additions to removals.
Depending on your perspective, it is a) a succinct decoy-and-nullifier set such as used in ZCash and Monero (but without an ever-expanding nullifier set); b) a cryptographic accumulator scheme with unlinkable set updates; or c) a mixnet without operators. In the context of cryptocurrencies, mutator sets are capable of concealing the links between transaction outputs and inputs without sacrificing scalability.



Dr. Alan Szepieniec obtained his PhD from KU Leuven, Belgium, in 2018, on the topic of post-quantum cryptography. After that he pivoted towards hash function design and interactive proof systems in the capacity of researcher for various blockchain foundations. Since 2022 he has been working as co-founder and chief architect of the Neptune cryptocurrency ( which uses Mutator Sets to succinctly represent the UTXO set.