E06 with Jens Groth: Scaling Zero-Knowledge Proofs with Instruction Sorting

In this episode, Dylan sat down with Jens Groth (pronounced “Yens”)—Chief Scientist at Nexus, creator of the Groth16 SNARK—to map how verifiable computation reaches internet scale. We unpack Nexus’s zkVM (RISC-V), its distributed prover network (orchestrator + workers) for low-latency proving, and why proofs-of-proofs are the practical path to tiny, fast-verifying artifacts. Jens explains the coming shift to instruction sorting—bucketing additions/XORs/etc. to cut redundant constraints—and where privacy fits when you parallelize proving. We also compare ZK vs TEE vs FHE in real systems, talk formal verification on the verifier path, and preview Nexus’s L1 that makes proofs first-class citizens for DeFi and beyond. How a zkVM compiles, executes, and emits an extended witness + proof—and what the verifier actually checks. Why a centralized orchestrator plus many workers wins on latency today, and where that clashes with privacy. The real trade-offs between TEEs (TDX/SEV) for speed, ZK for public verifiability, and FHE/MPC for data-in-use privacy. Instruction sorting: reordering the execution trace into per-op buckets to shrink constraints—an orders-of-magnitude lever when combined with proof composition. What “maturity” looks like in ZK stacks: open source, audits, formal verification for verifiers, supply-chain discipline, and reproducible builds. Nexus — zkVM v3 overview, distributed prover network, and blog updates: https://specification.nexus.xyz/ • https://docs.nexus.xyz/zkvm • https://blog.nexus.xyz/nexus-zkvm-3/ • https://blog.nexus.xyz/nexus-launches-worlds-first-open-prover-network/ Phala Network docs — confidential computing stack & TDX direction: https://docs.phala.com/overview/phala-network dstack-TEE — builder notes for attested, policy-driven confidential compute: https://phalanetwork.mintlify.app/docs/overview/what-is-dstack RISC-V ISA resources (for how zkVMs model CPU steps): https://riscv.org/specifications/ratified/ STARK proving system background (why many zk stacks compose proofs): https://starkware.co/stark-101/ • https://starkware.co/stark/ If you’re building rollups, privacy-first apps, or just need verifiable backends, this one’s a blueprint: start efficient at the base proof, compose downward, verify in milliseconds, and use privacy where it truly survives distribution.