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SEASON 2 MODULE 2

The Sum-Check Protocol w/ Justin Thaler

In this module, Tracy Livengood and Justin Thaler provide a comprehensive introduction to the sum-check protocol and why it is so powerful, beginning with a catch-up on polynomials (univariate, multivariate, multilinear) as well as the important concept of multilinear extensions, and introduce the “equality” function. They go on to explain the mechanics of the sum-check protocol, detailing its goals and process, before walking us through the rounds of the protocol and demonstrating how it is applied. They then highlight the advantages of sum-check over other SNARK systems, and sketch the Spartan polynomial IOP. Toward the end, they delve into the Goldwasser, Kalai and Rothblum (GKR) protocol and discuss the trade-offs between this system and Spartan.

What you’ll learn:

  • 00:00 Intro
  • 02:40 Univariate, multivariate and multilinear polynomials
  • 07:13 Multilinear extensions
  • 16:03 The equality function
  • 20:33 Goal of the sum-check protocol
  • 22:40 Applying sum-check
  • 32:01 Application to R1CS
  • 37:03 Benefits of sum-check
  • 39:33 How Spartan polynomial IOP uses sum-check
  • 48:42 The GKR Protocol
  • 55:30 Trade-offs vs Spartan

Below is an accompanying reading list:

ZK Whiteboard Sessions is an educational series on all things zero knowledge. Presented by ZK Hack.

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