At the behest of the excellent Quorum Control company, I have carried out my first foray into both Rust and Web Assembly (abbr. Wasm), making a JavaScript/Wasm binding of the Hyperledger Indy Crypto library. The reason behind this undertaking is that Quorum Control (and others) need BLS cryptographic signature verification abilities in JavaScript applications (Web and Node.js), and Indy Crypto provides a solid implementation of this although in the Rust language.

Luckily, there are facilities for converting Rust code into Web Assembly, i.e. the wasm-bindgen tool. While still a fledgling project, it allows us to expose a JavaScript API for the BLS module of Indy Crypto. In practice, this is done by writing a set of Rust functions tagged so that they get exported by the binding generated by wasm-bindgen. Additionally, we produce two variants of the binding: One for Node.js and one for ECMAScript modules aware systems (such as the Webpack bundler), in order for it to work both server side and in the browser.