It's time for my monthly research report for September. As always, my thanks to the community for ongoing support of research in applied cryptography.
Research contributor cargodog proposed a clever method for using Gray codes in Groth/Kohlweiss proofs, and suggested an adaptation for use in Triptych and Arcturus. I used this idea to produce working prototypes:
The efficiency tradeoffs for this method are subtle and interesting, and depend highly on the input anonymity size for the proofs, as well as how batching is constructed.
I made other updates to the code for Triptych and Arcturus as well. I updated the Triptych code in Python to support batch verification across proofs within the same transaction. The Arcturus Python code received updates for efficient verification and a better construction for aggregation coefficients.
The Arcturus preprint received attention as well. The correctness proof was expanded to more clearly show important derivations. The treatment of the linking tag as an injective one-way pseudorandom function was slightly modified for clarity. Discussion of the correspondence between witnesses for two relations was modified to better describe the connection to a particular cryptographic hardness assumption. And the precise proof statement for transaction applications was added in greater detail. Taken together, these updates make the preprint more clear and complete for readers.
I gave several talks this month. At the recent Magical Crypto Conference, I gave a talk on the collision between theory and practice in privacy techniques, and also participated in a panel on privacy. At the ESORICS CBT workshop, I gave a presentation on Triptych. Finally, I led a short discussion on Triptych for the Chicago BITDEVS group.
There were other assorted tasks and updates. I updated prototyping code for the Bulletproofs range proving system to extend its data embedding, adding additional data that can be secretly stored and recovered by the prover. Similarly, I updated the code for the Bulletproofs+ range proving system to add data embedding as well. I have been participating in ISO-affiliated workgroups to assist in developing standards like ISO/TR 23244, which helps to define aspects of distributed ledgers relating to personally-identifiable information and privacy techniques. Finally, I have been assisting research contributors studying the security implications of hypothetical quantum adversaries relating to the Monero protocol, providing data and reviewing results.
And now on to Sarang's Reading Corner, a short listing of some interesting papers that I have come across this month. The appearance of a paper in this list does not mean that I necessarily agree with its contents or correctness, or that I endorse it. Papers are in no particular order.
- Bitcoin--Monero Cross-chain Atomic Swap
- Anti-Money Laundering Regulation of Privacy-Enabling Cryptocurrencies
- MuSig-DN: Schnorr Multi-Signatures with Verifiably Deterministic Nonces
- SeF: A Secure Fountain Architecture for Slashing Storage Costs in Blockchains
- Lunar: a Toolbox for More Efficient Universal and Updatable zkSNARKs and Commit-and-Prove Extensions
- Hashing to elliptic curves
y^2 = x^3 + bprovided that
bis a quadratic residue
- Attacking Threshold Wallets
- Mimblewimble Non-Interactive Transaction Scheme
Dr. Sarang Noether