Universal SHA-256 digest library (@digitalcredentials/sha256-universal)

A minimal Typescript SHA-256 digest library for Node.js, browsers, and React Native.

Table of Contents

• Background
• Security
• Install
• Usage
• Contribute
• License

Background

In implementing Verifiable Credentials related libraries, we make frequent use of SHA-256 digests, and found ourselves re-implementing the same digest functions that had to run using native code whenever possible (native Node.js and browser WebCrypto API), but could also drop down to pure JS implementation for React Native.

Other universal SHA-256 libraries we've encountered either did not use the native implementations, or did not support React Native.

Security

• For Node.js, uses native Node crypto
• In browsers, uses the built-in WebCryptography API
• In React Native, uses the Microsoft Research library (msCrypto) via isomorphic-webcrypto.

Install

• Node.js 16+ is recommended.

NPM

To install via NPM:

npm install @digitalcredentials/sha256-universal

Development

To install locally (for development):

git clone https://github.com/digitalcredentials/sha256-universal.git
cd sha256-universal
npm install

Usage

Usable in Typescript and Javascript.

import { sha256digest } from '@digitalcredentials/sha256-universal'

// The digest function accepts either a string
await sha256digest('test')
// Uint8Array(32) [159, 134, 208, 129, 136,  76, 125, 101, 154,  47, 234, 160, 
// 197,  90, 208,  21, 163, 191,  79,  27,  43,  11, 130,  44, 209,  93, 108,  
// 21, 176, 240,  10,   8]

// or a raw byte array
const data = new TextEncoder().encode('test')
// Uint8Array(4) [ 116, 101, 115, 116 ]
await sha256digest(data)
// Uint8Array(32) [159, 134, 208, 129, 136,  76, 125, 101, 154,  47, 234, 160, 
// 197,  90, 208,  21, 163, 191,  79,  27,  43,  11, 130,  44, 209,  93, 108,  
// 21, 176, 240,  10,   8]

// If you want to hash a JS object, use JSON.stringify() first
const data = JSON.stringify({ "hello": "world" })
// '{"hello":"world"}'
await sha256digest(data)

Notice that the resulting hash digest is just an array of raw bytes. If you're intending to hash an object in order to obtain a deterministic content-addressable identifier string (for use in a database, for example), then you need to pass the result of sha256digest() to a base-X encoding function like base64url-universal.

Contribute

PRs accepted.

If editing the Readme, please conform to the standard-readme specification.

License

MIT License © 2022 Digital Credentials Consortium.