ETHEREUM PRIVACY TECHNOLOGIES Zero-Knowledge (ZK) and Fully Homomorphic Encryption (FHE) on Ethereum are often grouped together: “Both provide privacy.” But the truth is: 👉 They don't solve the same problem. 👉 They are not technologies from the same era. 🔐 What is ZK? ZK allows you to prove that you performed a computation correctly. But you don't reveal how you did it. In most cases: • The inputs of the transaction are public • The secret part (witness) is inside the proof • The verifier sees the result but not the method Thus, the essence of ZK is: 🧠 Proof privacy 🔒 What is FHE? FHE is a completely different level of technology. • The input is encrypted • The state is encrypted • Smart contracts perform computations without ever decrypting the data In other words, the system: “Performs operations without even knowing what it is doing.” Thus, the essence of FHE is: 🧠 Data privacy 🏗️ The maturity difference is critical ZK: ✅ Production-grade ✅ ZK-Rollups are already in use ✅ It has become a backbone of the Ethereum ecosystem FHE: 🧪 Testnet 📚 Academic and experimental ⏳ Not yet ready for large-scale production The technology in use today is clear: ZK ⚡ Performance reality (don't romanticize it) ZK: • Proof generation can be difficult • But verification is very fast FHE: • Biggest issue: bootstrapping • Computation is extremely slow • Cost is high • User experience is nearly a nightmare FHE today = expensive + slow 🧩 Why are their use cases different? ZK: • Scaling • Rollups • Verifiability • zk-login, zk-identity ZK is an infrastructure technology. FHE: • Private smart contracts • Private DeFi • Encrypted voting • Private computation FHE is a privacy utopia. 🧱 Main problems ZK's challenges: • Prover/verifier efficiency • Hardware • Cost • Latency FHE's challenges: • Cost of encrypted computation • Key management • User experience 🎯 Don't miss the big picture 🟦 ZK = Today's Ethereum 🟥 FHE = Tomorrow's Ethereum (but not yet) And in one sentence to summarize the difference: 👉 ZK: “I prove that I did it correctly” 👉 FHE: “I do it without anyone seeing what I did” That's why ZK and FHE are not competitors. ⛓️ They are technologies from different time periods of the same chain. Today, ZK is keeping Ethereum alive. In the future, FHE may step onto the stage. But not today.