Schnorr Crypto

Based on zenroom, uses curve BLS461 from the Millagro library.

The way it works is that Zenroom uses the Milagro library for the elliptic curve and finite field stuff. It's all written in C and scriptable using Lua. This is then compiled into wasm using emscripten.

The arguments for the Lua scripts are passed as JSON encoded strings. To get output back from the scripts, the print(JSON.encode({})) command is used.

So the cryptography is implemented in Lua, see scripts/*.lua.

There is a build.js script that prepends the contents of prelude.lua to each other script and produces lua-scripts.js. Run npm run bundle-lua to update this file.

API

const S = require('zenroom-schnorr')

• random(rngseed) => hex
• keypair(rngseed) => {private, public}
• sign(keypair, message, rngseed) => {s, R}
• verify(signature, public, message) => bool

All calls are async/Promise.

Deterministic behaviour

You can pass a random number generator seed to the functions that use random numbers (random, keypair, sign) to make them deterministic.

Watch out that you don't generate a keypair with the same nonce.

// must be 256 bytes
const rngseed = '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'

Generating a random number

const rnd = await S.random(rngseed)

Creating a keypair

const {private, public} = await S.keypair(rnd)

Signing a message

const m = 'deadbeef'
const {s, R} = await S.sign({private, public}, m, rnd)

Verifying a signature

const isValid = await S.verify({s, R}, public, m)