This article explores Zero-Knowledge Proofs (ZKP) support on the Stellar blockchain, focusing on Soroban's host functions for BLS12-381 and upcoming X-Ray upgrade adding BN254 and Poseidon hash functions. It explains elliptic curves, their security differences, and how these primitives enable efficient ZK smart contracts. The enhancements promise smoother migrations, better performance, and lower costs for privacy-preserving apps on Stellar.
The article dives into Stellar's adoption of advanced ZKP systems via its Soroban smart contract platform, which uses Rust and WebAssembly. In 2024, Stellar added host functions for the secure BLS12-381 elliptic curve, enabling efficient ZKP operations without heavy computation in Wasm. The upcoming X-Ray protocol upgrade, via CAP-0074 and CAP-0075, will introduce native support for BN254 (for EVM compatibility) and Poseidon hash functions optimized for ZK circuits. These developments address performance bottlenecks, allow seamless migration of existing ZK apps, reduce costs, and bridge Stellar to the broader ZK ecosystem. Host functions act as native, optimized APIs for complex crypto math, likened to a starship's nav-computer. The piece highlights Stellar's strategic choices for long-term security and developer flexibility.