xsalsa20-csprng

CSPRNG and crypto library powered by XSalsa20. Small, fast, supports both browsers and Node.js, and optimized for CSPRNG usage.

pnpm add xsalsa20-csprng

This library is optimized to be used as CSPRNG rather than encrypting large data. Thus, this library doesn't contain native code or webassembly binding to reduce FFI overhead.

Usage

class XSalsa20CSPRNG

See reference for the further details.

import XSalsa20CSPRNG from 'xsalsa20-csprng'

const rng = new XSalsa20CSPRNG()

// Random 32bit int (-2147483648 ≤ x < 2147483648), takes about 85ns per each call
const i = rng.randomInt32()
// Random 32bit unsigned int (0 ≤ x < 4294967296)
const u = rng.randomUint32()
// Random int of desired range (0 ≤ x < 10)
const n = rng.uniformInt(10)

// You can use fixed nonce and key
const nonce = new Uint8Array([/* nonce with 24 bytes */])
const key = new Uint8Array([/* key with 32 bytes */])
const deterministic = XSalsa20CSPRNG.of(nonce, key)
// Fixed nonce and key will result in deterministic output
console.log(deterministic.randomInt32())
console.log(deterministic.randomInt32())
console.log(deterministic.randomInt32())

class XSalsa20

See reference for the further details.

import { XSalsa20 } from 'xsalsa20-csprng'

const nonce = new Uint8Array([/* nonce with 24 bytes */])
const key = new Uint8Array([/* key with 32 bytes */])

// Encrypt
const encoder = new XSalsa20(nonce, key)
const plaintext = Uint8Array.from('message')
const ciphertext = encoder.update(plaintext)

// Decrypt : same with encryption
const decoder = new XSalsa20(nonce, key)
const decrypted = decoder.update(ciphertext)
// plaintext and decrypted have same contents

// You can retrieve XSalsa20 streams if you want
const gen = new XSalsa20(nonce, key)
console.log(gen.stream(64))
console.log(gen.stream(64))