In April 2026, delivered a circuit-driven refactor of zkVM public input handling to align PI processing with circuit semantics, improving verification reliability and reducing ambiguity in input ordering. The work centers on canonical PI representation via instance_values and instance_openings, with PI openings derived from PublicValues MLEs to ensure end-to-end consistency across prover, Rust verifier, and recursion verifier. This month also fixed critical soundness gaps by removing wit_in_evals and fixed_in_evals from the proof payload and deriving these values deterministically from sumcheck evaluations during verification. The changes establish a robust foundation for future hardening of public inputs and safer protocol upgrades.

March 2026 (scroll-tech/ceno): Focused on stabilizing and accelerating the ZKVM verifier. Consolidated and simplified verifier logic by standardizing instance handling across prove/verify paths and unifying the production check flow via a new state continuation mechanism. This reduces complexity, improves readability, and boosts performance. Implemented architectural changes alongside code cleanups, ensuring a tighter parity between prove/verify paths and reducing maintenance risk. Commit-driven work laid groundwork for future optimizations and more reliable production checks.

February 2026 monthly summary for scroll-tech/ceno. Focused on performance and throughput enhancements of the ZK proof system and related developer ergonomics. Delivered core optimizations to speed up proofs, improve throughput, and reduce memory copies, along with a user-facing runbook to improve onboarding.

January 2026 Performance Summary for scroll-tech/ceno Key features delivered: - Keccak circuit mask representation optimization: Refactored MaskRepresentation to reduce dynamic allocations, yielding dramatic witness-generation time improvements across shards (notably shards 3–8 with up to ~88% faster times). - FullTracer performance optimization: Skipped next_access updates to reduce overhead, delivering ~7–8% faster core components (reth-block and app.prove) and enabling more responsive end-to-end proofs. - ShardContext bug fix: Corrected hint condition handling for heap/hint addresses, improving address-range correctness. - Secp256r1 signature verification and syscall support: Implemented verification path in pure RISCV with added syscall specs; validated with Ethereum L1 proofs, reducing verification cycles (11.9M -> 11.7M) and resolving prior emulator panics. - Opcode dispatching optimization with reusable record buffers: Reworked dispatch flow to reuse buffers, cutting per-shard timings by roughly 9% on average and simplifying emulator emit steps. - ECC quark prover GPU acceleration and GPU optimizations: Moved major ECC quark workloads to GPU and introduced GPU-friendly optimizations (monomial factorization, sparse selectors), achieving substantial speedups in prove_main_constraint and overall end-to-end times on large blocks (e.g., 24169100). - Supporting improvements: Ordered sparse 64 selectors and related updates to widen GPU-CPU collaboration and reduce kernel launch overhead. Major bugs fixed: - ShardContext hint condition bug fix addressing #1215 (fixes incorrect address-range handling in heap/hint addresses). Overall impact and accomplishments: - Substantial performance gains across cryptographic and circuit workloads, enabling faster proofs and witness generation, lower GPU/CPU cost, and improved reliability for large-block proofs. - Demonstrated end-to-end stability on large Ethereum L1-like blocks and improved correctness in critical address-handling code paths. Technologies/skills demonstrated: - Performance engineering: dynamic memory optimization, vector allocation reduction, and reuse of record buffers. - Cryptography: secp256r1 verification integration and syscall modeling; GPU-accelerated ECC proof paths. - Systems integration: e2e verification against Ethereum L1, RISCV-based verification paths, and cross-component benchmarking. - Debugging and reliability: bug fixes in ShardContext hint conditions, improved latency and throughput under load.

December 2025 Monthly Summary for Scroll Tech (repo: scroll-tech/ceno) focused on delivering core performance, reliability, and developer experience improvements across the Proof system, with clear business value in throughput, observability, and maintainability.

November 2025 performance summary for scroll-tech/ceno: Delivered major architectural, GPU, and cryptographic improvements that scale across shards, acceleration of witness generation, and enhanced observability. The work emphasizes business value through increased throughput, reduced prover cycles, and more robust debugging.

October 2025 performance-focused update for scroll-tech/ceno: migrated GPU tower proof to the new create_proof API, instrumented comprehensive benchmarks, and produced latency breakdowns to quantify improvements. The change delivered measurable throughput gains and more predictable latency for proof generation, enabling higher load handling and faster iterations. Benchmarks (CPU 5900XT 32 cores, GPU RTX 5070 TI 16GB) show ~21-23% reductions in proof times across tested fib benchmarks and up to ~1.30x speedups. Included detailed latency traces and a baseline comparison against master to support ongoing optimization.

September 2025 (scroll-tech/ceno) monthly summary focused on reliability, correctness, and maintainability improvements in cryptographic and memory-related components of the ZKVM workflow. The work stabilizes test behavior, eliminates sources of transcript variability, and strengthens memory allocation guarantees, delivering clear business value and technical quality.

Month: 2025-08. This month delivered significant performance, reliability, and scalability improvements for scroll-tech/ceno's ZKVM stack. Key features delivered include core ZKVM circuit and memory performance optimizations: static selector witness generation for GKR-IOP, optimized witness inference, limb-based memory representation, limb-based mulh circuit, improved less-than and range checks, enhanced shift logic, and Keccak precompile limb handling (9 commits: 842d35e04df216aaea3fb0bc2b62386b609e27e4; d0b28b9f0de3fe3e094482bdff0feda483a6dec4; 0a960a4937fa7ee403ef972fcf95f2d9b881b130; a951275e2e01dc28348b4529c2fd30c06ca0047a; 4b4de4f670ec966b6d51f938bacde4a314471983; 0c89843fff4e657ebee6b6196a50d8d823e82caf; dc5a22ad0f541e49a2a9643c2e3ef047267d50c9; bad8dcace3a078c9f39bfb8411faec3e775c25ed; 815afe40077510537d64c31ce3a91696f0eef9a2).

July 2025 highlights for scroll-tech/ceno: Delivered a modular prover backend capable of supporting separate CPU and GPU implementations, enabling hardware-accelerated proofs and improved latency. Implemented cross-crate utilities and shared primitives (zkvm and gkr_iop) to streamline development and reduce duplication. Integrated the Keccak precompile into the end-to-end flow with memory read/write in the precompile circuit, and introduced a new ComposedConstrainSystem wrapper for the Keccak flow, defining Keccak as a first-class ecall-opcode and enabling cross-crate lookup table sharing. These changes enhance performance, flexibility, and maintainability, unlocking faster proof generation and broader hardware options.

June 2025 highlights for scroll-tech/ceno focused on refactoring the core constraint machinery to improve maintainability, reusability, and future-proofing. Delivered a generalized GKR sumcheck layer and pre-compilation alignment, with backend expressions cached inside the constraint system. This reduces future refactoring risk, simplifies the main sumcheck’s read/write lookup expression, and removes the post-evaluate() call without sacrificing performance.

May 2025: scroll-tech/ceno delivered a series of architectural and performance upgrades that strengthen reliability, developer experience, and end-user performance. Key initiatives include centralizing MLE expression handling in the multilinear_extensions crate, enabling reuse and consistency across the codebase; pre-allocating witness vectors with parallel allocation to reduce runtime overhead; integrating jemalloc as an optional global allocator to boost performance; adding 64-bit cycle counts in ZKVM to align with newer toolchains; and introducing a no-syscall Keccak implementation with host-side support to improve portability and testing. Additional tooling improvements (Cargo debug mode and enhanced IO visibility on failure) and protocol-level optimizations further contributed to stability and efficiency. These changes position Ceno for higher throughput, better scalability, and faster iteration in development and CI pipelines.

April 2025 performance and reliability sprint for scroll-tech/ceno. Delivered major MPCS performance improvements, enhanced runtime instrumentation, and stabilized CI/build pipelines, alongside a critical verifier padding fix and toolchain upgrade. The month reinforced end-to-end throughput, observability, and development reliability, with a modernization of the Rust toolchain to enable optimizations and reformats.

March 2025 highlights for scroll-tech/ceno: Delivered substantial Prover/Verifier core refactor and sumcheck enhancements, introduced detailed ZKVM proof size statistics with per-circuit attribution, fixed end-to-end proof validity through a halt-detection bug fix, and expanded public I/O support with end-to-end testing improvements. Also centralized dependencies via a new p3 crate and aligned CI/build workflows for easier maintenance and scalability.

February 2025 performance summary focused on delivering robust end-to-end ZK workflows, improving caching reliability, and refining data structures for 2-adic generators. The work across two repositories demonstrates value through both feature advancement and stability improvements.

January 2025 (2025-01) – Scroll Tech/ceno: Codebase modernization and refactor to remove v2 suffix and unify prover/virtual polynomial logic. This work reduces technical debt, standardizes interfaces, and prepares the codebase for future enhancements. No major defects fixed this month; focus was on architectural cleanup and maintainability, with one committed change that encapsulates the refactor.

December 2024 monthly summary for scroll-tech/ceno: Focused on delivering measurable performance tooling improvements and cleaner logs to enable faster debugging and reproducible benchmarks. Key features delivered, major bugs fixed, and the broader business impact are summarized below.

November 2024 performance summary for scroll-tech/ceno: Delivered significant platform enhancements and a critical bug fix with measurable impact on reliability and resource efficiency. Key deliveries include a unified SRA opcode with refined shift operation flow, and a streamlined thread management model using max_usable_threads. Also resolved a minimal-table sumcheck edge case, extending verifier correctness and test coverage. Emphasis on maintainability, documentation, and robust testing to support future scalability.

Month 2024-10 — Delivered modular circuit architecture with end-to-end public I/O and prover/verifier protocol for the scroll-tech/ceno repository. Implemented modular circuits for non-volatile and volatile tables, refactored memory management by separating program data into a dedicated circuit and keeping memory volatile, and added a prover/verifier protocol for evaluating public I/O and handling table address arguments. Change is tracked via commit 6541209c02e62566bc0b805bf6ff97ce3d0c656c (#457).