Cryptology ePrint Archive: Report 2021/1173

Lelantus Spark: Secure and Flexible Private Transactions

Aram Jivanyan and Aaron Feickert

Abstract: We propose a modification to the Lelantus private transaction protocol to provide recipient privacy, improved security, and additional usability features. Our decentralized anonymous payment (DAP) construction, Spark, enables non-interactive one-time addressing to hide recipient addresses in transactions. The modified address format permits flexibility in transaction visibility. Address owners can securely provide third parties with opt-in visibility into incoming transactions or all transactions associated to the address; this functionality allows for offloading chain scanning and balance computation without delegating spend authority. It is also possible to delegate expensive proving operations without compromising spend authority when generating transactions. Further, the design is compatible with straightforward linear multisignature operations to allow mutually non-trusting parties to cooperatively receive and generate transactions associated to a multisignature address. We prove that Spark satisfies formal DAP security properties of balance, non-malleability, and ledger indistinguishability.

Category / Keywords: cryptographic protocols /

Date: received 13 Sep 2021, last revised 23 Sep 2021

Contact author: aram at firo org, aaron at cypherstack com

Available format(s): PDF | BibTeX Citation

Note: Fixes a tag issue identified by Nikolas Krätzschmar. Updates notation and proofs.

Version: 20210923:162945 (All versions of this report)

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