a16z Crypto updates Jolt zkVM, flags misuse of the term 'ZK'

Andreessen Horowitz (a16z)’s Web3 arm, a16z Crypto, has updated the open-source Jolt zkVM and said the developer ecosystem is overusing the term “ZK.”

According to a report by The Block on the 3rd (local time), a16z Crypto said in a recent blog post that many zkVMs in fact do not provide full zero-knowledge. The post explained: “Most zkVMs are not truly zero-knowledge unless they go through a separate, costly ‘wrapping’ procedure.”

It added that this wrapping procedure—recursively proving the zkVM verification process inside another zero-knowledge proof system—comes with high computational costs and requires a trusted setup, meaning some transparency must be sacrificed.

a16z Crypto also emphasized that “zk” has recently been used almost as an abbreviation for proof succinctness—i.e., proofs that are short and quickly verifiable—which differs from the original concept of zero-knowledge. It noted that misuse of the term could be problematic at a time when the importance of privacy is resurfacing among developers and investors.

A zero-knowledge proof is a cryptographic technique that allows one party to prove to another that a given statement is true without revealing any other information. The technology became widely known through Zcash’s use of zk-SNARKs to hide on-chain transaction data, and its applications have since expanded to areas such as Ethereum Layer 2 and zk-rollup scaling solutions.

In this update, a16z Crypto introduced the NovaBlindFold folding scheme into Jolt zkVM, improving it so that it supports zero-knowledge proofs by default. NovaBlindFold is based on a structure proposed in the 1990s and generates blind proofs that prevent information leakage during the proving process.

a16z Crypto said, “With this improvement, Jolt zkVM has shifted to an architecture suited for privacy applications,” adding that “the zero-knowledge proofs generated after the update increase by only about 3 kilobytes compared with the previous non-zero-knowledge Jolt proofs, preserving efficiency.”