KVaC: Key-Value Commitments for Blockchains and Beyond

Srinivasan Raghuraman


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.

In this talk, I will introduce 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.

The results in this talk are based on a joint work with Shashank Agrawal that is available online (https://eprint.iacr.org/2020/1161.pdf) and is to appear at ASIACRYPT'20.


Srinivasan (Srini) Raghuraman received his B.Tech. in Computer Science and Engineering from IIT Madras in 2015, and his S.M. and Ph.D. in Cryptography from MIT in 2017 and 2020 respectively, working with Prof. Shafi Goldwasser, specializing in infrastructures for secure multi-party computation. Currently, he is a Staff Research Scientist at Visa Research. He is a recipient of the President of India Prize for the best academic performance at IIT Madras, as well as the Carlton E. Tucker Teaching Award and Irwin Mark Jacobs and Joan Klein Jacobs Presidential Fellowship at MIT. He is also a Siebel Scholar, Class of 2017, a scholarship awarded annually for academic excellence and demonstrated leadership to over 90 top students from the world’s leading graduate schools.

Time and Place

Tuesday, November 10, 2:30pm