JavaScript implementation of the multibase specification

Oli Evans

• Install
  • In Node.js through npm
  • Browser: Browserify, Webpack, other bundlers
  • In the Browser through <script> tag
    • Gotchas
• Usage
  • Example
• API
  • multibase - Prefixes an encoded buffer with its multibase code
  • multibase.encode - Encodes a buffer into one of the supported encodings, prefixing it with the multibase code
  • multibase.decode - Decodes a buffer or string
  • multibase.isEncoded - Checks if buffer or string is encoded
  • multibase.names - Supported base encoding names
  • multibase.codes - Supported base encoding codes
  • Supported Encodings, see src/constants.js
• Architecture and Encoding/Decoding
• Adding additional bases
• License

> npm install --save multibase

The code published to npm that gets loaded on require is in fact an ES5 transpiled version with the right shims added. This means that you can require it and use with your favourite bundler without having to adjust asset management process.

const multibase = require('multibase')

Loading this module through a script tag will make the Multibase obj available in the global namespace.

<script src="https://unpkg.com/multibase/dist/index.min.js"></script>
<!-- OR -->
<script src="https://unpkg.com/multibase/dist/index.js"></script>

You will need to use Node.js Buffer API compatible, if you are running inside the browser, you can access it by multibase.Buffer or you can load Feross's Buffer module.

const multibase = require('multibase')

const encodedBuf = multibase.encode('base58btc', new Buffer('hey, how is it going'))

const decodedBuf = multibase.decode(encodedBuf)
console.log(decodedBuf.toString())
// hey, how it going

https://multiformats.github.io/js-multibase/

const multibased = multibase(<nameOrCode>, encodedBuf)

const encodedBuf = multibase.encode(<nameOrCode>, <buf>)

const decodedBuf = multibase.decode(bufOrString)

const value = multibase.isEncoded(bufOrString)
// value is the name of the encoding if it is encoded, false otherwise

A frozen Array of supported base encoding names.

A frozen Array of supported base encoding codes.

Multibase package defines all the supported bases and the location of their implementation in the constants.js file. A base is a class with a name, a code, an implementation and an alphabet.

class Base {
  constructor (name, code, implementation, alphabet) {
    //...
  }
  // ...
}

The implementation is an object where the encoding/decoding functions are implemented. It must take one argument, (the alphabet) following the base-x module architecture.

The alphabet is the ordered set of defined symbols for a given base.

The idea behind this is that several bases may have implementations from different locations/modules so it's useful to have an object (and a summary) of all of them in one location (hence the constants.js).

All the supported bases are currently using the npm base-x module as their implementation. It is using bitwise maipulation to go from one base to another, so this module does not support padding at the moment.

If the base you are looking for is not supported yet in js-multibase and you know a good encoding/decoding algorithm, you can add support for this base easily by editing the constants.js file (you'll need to create an issue about that beforehand since a code and a canonical name have to be defined):

const baseX = require('base-x')
//const newPackage = require('your-package-name')

const constants = [
  ['base1', '1', '', '1'],
  ['base2', '0', baseX, '01'],
  ['base8', '7', baseX, '01234567'],
  // ... [ 'your-base-name', 'code-to-be-defined', newPackage, 'alphabet']
]

The required package defines the implementation of the encoding/decoding process. It must comply by these rules :

• encode and decode functions with to-be-encoded buffer as the only expected argument
• the require call use the alphabet given as an argument for the encoding/decoding process

If no package is specified (such as for base1 in the above example, it means the base is not implemented yet)

Adding a new base requires the tests to be updated. Test files to be updated are :

• constants.spec.js

describe('constants', () => {
  it('constants indexed by name', () => {
    const names = constants.names
    expect(Object.keys(names).length).to.equal(constants-count) // currently 12
  })

  it('constants indexed by code', () => {
    const codes = constants.codes
    expect(Object.keys(codes).length).to.equal(constants-count)
  })
})

• multibase.spec.js
  • if the base is implemented

  const supportedBases = [
    ['base2', 'yes mani !', '01111001011001010111001100100000011011010110000101101110011010010010000000100001'],
    ['base8', 'yes mani !', '7171312714403326055632220041'],
    ['base10', 'yes mani !', '9573277761329450583662625'],
    // ... ['your-base-name', 'what you want', 'expected output']

  • if the base is not implemented yet

  const supportedBases = [
    // ... ['your-base-name']

Contributions welcome. Please check out the issues.

Check out our contributing document for more information on how we work, and about contributing in general. Please be aware that all interactions related to multiformats are subject to the IPFS Code of Conduct.

Small note: If editing the README, please conform to the standard-readme specification.

MIT © 2016 Protocol Labs Inc.