Production ZK: Privacy Pools, Identity, Rollups

What you'll learn

• From Theory to Production
• Tornado Cash and the Privacy Pool Reset
• ZK Identity: World ID, Privado, and Selective Disclosure
• Production zkEVMs and ZK Rollups
• zkBridges: ZK for Trustless Cross-Chain
• Where ZK Is Going

Key terms

Tornado Cash

A 2019 Ethereum mixer using Circom Groth16 proofs. Sanctioned by OFAC on August 8, 2022; the Fifth Circuit ruled in Van Loon v. Treasury (Nov 26, 2024) that immutable smart contracts are not property OFAC can sanction under IEEPA; OFAC delisted the contracts in March 2025.

Privacy Pools

A design proposed in a September 2023 paper co-authored by Vitalik Buterin and others in which users prove their funds are part of a "permitted" subset of deposits, enabling privacy while cryptographically dissociating from known illicit activity; an actual Privacy Pools protocol launched on Ethereum in 2024-2025.

Aleo

A privacy-focused L1 blockchain using zk-SNARKs and the Leo smart contract language. Mainnet launched September 25, 2024.

Aztec Network

A privacy-focused L2 using Noir for smart contracts and a private-by-default state model; progressed through testnets toward mainnet through 2024-2025.

World ID

A proof-of-personhood protocol using iris-scanning hardware (the Orb) and Semaphore-based ZK proofs of group membership; lets users prove they are unique humans without revealing which human.

Semaphore

A Circom-based ZK anonymity primitive developed by the Privacy and Scaling Explorations group; lets users prove group membership and anonymously signal while preventing double-signaling. Underlies World ID and many other systems.

Privado ID

A decentralized identity system (rebranded from Polygon ID in 2024) based on the iden3 protocol; users hold verifiable credentials and produce ZK proofs of selective attribute disclosure.

zkBridge

A cross-chain bridge architecture using ZK proofs of source-chain consensus signatures and block headers, allowing destination chains to verify cryptographically rather than trust an external validator multisig.

Polyhedra Network

A commercial provider of ZK light-client bridges between EVM and non-EVM chains; one of the leading production zkBridge implementations.

Succinct Telepathy

A ZK light client for Ethereum, providing other chains with cryptographic verification of Ethereum block headers; integrated into the broader Succinct SP1 ecosystem.