This is a companion to my talk. Not a whitepaper, not a sales pitch — just the stuff you'd actually want open in a tab if you sat down to build something private this week.
Different privacy problems need different crypto primitives. Here's where things stand:
| Tech | Good For | Verification | Maturity |
|---|---|---|---|
| ZK-SNARKs | Private transfers, identity proofs | < 10ms | Production (Noir/Circom) |
| TEEs (SGX) | Dark pools, MEV protection | Native | Hardware-dependent |
| FHE | On-chain confidential compute | ~1s+ | Early (Fhenix/Zama) |
Quick take: ZK-SNARKs are the only one ready for real users today. TEEs work but you're trusting Intel. FHE is exciting but slow — keep an eye on it, don't ship on it yet.
AztecZK DSLRust-like
Noir is to ZK circuits what Solidity was to the EVM — the thing that made it accessible. You write Rust-like code, it compiles to a ZK circuit. No cryptography PhD required.
If you want private smart contracts on Aztec's network, this is where you start.
DeFi PrivacyL1/L2PPOI
The go-to for adding privacy to existing DeFi. Swaps, transfers, LP positions — all shielded. The important bit: it has Private Proof of Innocence baked in, so you can stay private and compliant after the 2025 regulatory shifts.
Ethereum FoundationStealth AddressesERC-5564
The EF's official privacy toolkit. Gives you stealth addresses and ZK-compliance modules you can drop into any wallet or dApp. Three of the four core modules (Stealth, Compliance, Registry) are audited and live.
All assets need to support View Keys or ZK-Compliance Proofs for sanctions screening. Deadline: July 2026. If your protocol can't prove a transaction isn't from a sanctioned address without revealing the sender, you have a problem.
Focused on market abuse and MEV. Using privacy tools to hide wash trading = illegal. Using them to protect against front-running = encouraged. The line is intent, not the tool.
Hosting decentralised, non-custodial privacy code is protected activity. Writing Tornado Cash is fine. Running a mixer with a fee and no compliance = not fine.
The pitch from my talk: privacy on-chain is going through the same transition HTTPS did. It went from "sketchy" to "default". Here's the core equation if you want to reason about ZK proofs:
That's it. Everything else — Noir circuits, Railgun shielding, stealth addresses — is just a nicer interface for constructing that π.
"Privacy is not about hiding. It's about ensuring that whoever has the information doesn't have all the power."