Real World Crypto 2021 - Session 11: Invited Talk

   2021-01-14        RWC2021 · Real World Crypto

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Eli Ben Sasson (StarkWare) / Scaling Computations on Blockchains with ZK-STARKs / paper video slides

Plug for a language called Cairo cairo-lang.org. There’s a playground too.

zkp.science – a list of resources about zero-knowledge proofs.

His Pitch: “Blockchains == Inclusive Accountability” but sacrifice privacy and scalability. ZK-STARKs solve both problems, because anyone can download chain and verify.

SNARK = Succinct, Non-Interactive ARgument of Knowledge
STARK = Scaleable, Transparency ARgument of Knowledge

Solving for scaleability

• ZKPs go back to 1985. Explosion of implementations since.
• see blog post A Cambrian explosion of ZKPs
• STARKs vs SNARKs

ZK-STARKs: they can solve scale and privacy - in theory, and in practice!

• but how to make them accessible to all?

Why can’t blockchains meet the txns/per sec that VISA et al can? He claims: VISA run big iron that can do 10,000s txns/sec, but your laptop can’t.

ZK proof recap:

• privacy is from ZK: the prover’s private inputs are shielded
• scalability is from Prover running in linear time, and generating a proof that is exponentially smaller than the amount of data the prover had to process. The verifier has exponentially small (‘poly-log’) running time

On a blockchain: verifiers only need to see a Merkle root hash of all txns, they see prev root and proposed new root, and a proof, and this can be executed v quickly. The prover only has to see all the individual txns.

Transparency is the T in ZK-STARK. []“arthur - merlin protocol”](https://en.wikipedia.org/wiki/Arthur%E2%80%93Merlin_protocol)

SNARK - S = succinct; N = Non-Interactive (set-up may require huge computation time and must be highly trusted. (remember zcash genesis?) He calls the need for these properties ‘toxic’ and claims that ZK-STARK is ‘non-toxic’.

Cairo: MVL (minimal viable language) for production STARK systems

If you write using Cairo code, then you get a ZKP verifier for free as part of Cairo.
This has been launched on the Ethereum test net.