KVaC: Key-Value Commitments for Blockchains and Beyond

KVaC: Key-Value Commitments for Blockchains and Beyond

Cybersecurity Seminars Online seminar
Thursday, 18 February 2021
12 pm - 1 pm (AEDT)

As blockchains grow in size, validating new transactions becomes more and more resource intensive. To deal with this, there is a need to discover compact encodings of the (effective) state of a blockchain -- an encoding that allows for efficient proofs of membership and updates. In the case of account-based cryptocurrencies, the state can be represented by a key-value map, where keys are the account addresses and values consist of account balance, nonce, etc.

We propose a new commitment scheme for key-value maps whose size does not grow with the number of keys, yet proofs of membership are of constant-size. In fact, both the encoding and the proofs consist of just two and three group elements respectively (in groups of unknown order like class groups). Verifying and updating proofs involves just a few group exponentiations. Additive updates to key values enjoy the same level of efficiency too.

Key-value commitments can be used to build dynamic accumulators and vector commitments, which find applications in group signatures, anonymous credentials, verifiable databases, interactive oracle proofs, etc. Using our new key-value commitment, we provide the most efficient constructions of (sub)vector commitments to date.

About the speaker

Srinivasan Raghuraman
Staff Research Scientist, Visa Research

Dr. Srinivasan Raghuraman joined Visa Research as a Staff Research Scientist in June 2020. Srini received his Ph.D. in Cryptography from MIT in 2020 working with Prof. Shafi Goldwasser, specializing in infrastructures for secure multi-party computation. His Ph.D. thesis focused on enabling reliable communication, secure computation, and fair computation in an incomplete network that also provides reusability, transferability, and fault-tolerance.

As a member of the Advanced Cryptography and Blockchain teams, his research interests are in cryptography, blockchain, and secure computation. He has published papers in several international conferences and journals, including CRYPTO, EUROCRYPT, Theory of Cryptography Conference (TCC), International Association for Cryptologic Research International Conference on Practice and Theory of Public-Key Cryptography (IACR PKC), and others.


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