Building a Faster secp256k1 Library – UltrafastSecp256k1 v3.21

I’ve been working on UltrafastSecp256k1, a high‑performance secp256k1 cryptography library focused on throughput and auditability. The new v3.20 release consolidates more than 120 commits and introduces major improvements in constant‑time security, performance, and testing infrastructure. Key highlights: • Constant‑time scalar inversion rewritten using Bernstein‑Yang SafeGCD • 6.4× improvement in scalar inverse • ~43% faster constant‑time ECDSA signing • strict BIP‑340 parsing and safer APIs • expanded audit infrastructure • reproducible Docker CI pipeline Benchmarks across several architectures show strong performance improvements compared to libsecp256k1 in signing workloads and generator multiplication. The project now includes: • cross‑platform benchmark campaigns • formal constant‑time verification tools • Wycheproof and Fiat‑Crypto verification • full local Docker CI GitHub: https://github.com/shrec/UltrafastSecp256k1