https://github.com/cryptocoinjs/base-x

Encode/decode any base
https://github.com/cryptocoinjs/base-x

alphabet base base58 bitcoin decoding encoding

Last synced: 4 days ago
JSON representation

Encode/decode any base

• Host: GitHub
• URL: https://github.com/cryptocoinjs/base-x
• Owner: cryptocoinjs
• License: mit
• Created: 2015-05-19T04:25:00.000Z (over 9 years ago)
• Default Branch: master
• Last Pushed: 2024-07-04T07:48:37.000Z (7 months ago)
• Last Synced: 2025-01-14T03:45:57.939Z (8 days ago)
• Topics: alphabet, base, base58, bitcoin, decoding, encoding
• Language: JavaScript
• Size: 217 KB
• Stars: 317
• Watchers: 13
• Forks: 75
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE.md

Awesome Lists containing this project

README

        
# base-x

[![NPM Package](https://img.shields.io/npm/v/base-x.svg?style=flat-square)](https://www.npmjs.org/package/base-x)

[![Build Status](https://img.shields.io/travis/cryptocoinjs/base-x.svg?branch=master&style=flat-square)](https://travis-ci.org/cryptocoinjs/base-x)

[![js-standard-style](https://cdn.rawgit.com/feross/standard/master/badge.svg)](https://github.com/feross/standard)

Fast base encoding / decoding of any given alphabet using bitcoin style leading

zero compression.

**WARNING:** This module is **NOT RFC3548** compliant,  it cannot be used for base16 (hex), base32, or base64 encoding in a standards compliant manner. 

## Example

Base58

``` javascript

var BASE58 = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'

import basex from 'base-x'

var bs58 = basex(BASE58)

var decoded = bs58.decode('5Kd3NBUAdUnhyzenEwVLy9pBKxSwXvE9FMPyR4UKZvpe6E3AgLr')

console.log(decoded)

// => Uint8Array(33) [

//   128, 237, 219, 220,  17, 104, 241, 218,

//   234, 219, 211, 228,  76,  30,  63, 143,

//    90,  40,  76,  32,  41, 247, 138, 210,

//   106, 249, 133, 131, 164, 153, 222,  91,

//    25

// ]

console.log(bs58.encode(decoded))

// => 5Kd3NBUAdUnhyzenEwVLy9pBKxSwXvE9FMPyR4UKZvpe6E3AgLr

```

### Alphabets

See below for a list of commonly recognized alphabets, and their respective base.

Base | Alphabet

------------- | -------------

2 | `01`

8 | `01234567`

11 | `0123456789a`

16 | `0123456789abcdef`

32 | `0123456789ABCDEFGHJKMNPQRSTVWXYZ`

32 | `ybndrfg8ejkmcpqxot1uwisza345h769` (z-base-32)

36 | `0123456789abcdefghijklmnopqrstuvwxyz`

58 | `123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz`

62 | `0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ`

64 | `ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/`

67 | `ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_.!~`

## How it works

It encodes octet arrays by doing long divisions on all significant digits in the

array, creating a representation of that number in the new base. Then for every

leading zero in the input (not significant as a number) it will encode as a

single leader character. This is the first in the alphabet and will decode as 8

bits. The other characters depend upon the base. For example, a base58 alphabet

packs roughly 5.858 bits per character.

This means the encoded string 000f (using a base16, 0-f alphabet) will actually decode

to 4 bytes unlike a canonical hex encoding which uniformly packs 4 bits into each

character.

While unusual, this does mean that no padding is required and it works for bases

like 43. 

## LICENSE [MIT](LICENSE)

A direct derivation of the base58 implementation from [`bitcoin/bitcoin`](https://github.com/bitcoin/bitcoin/blob/f1e2f2a85962c1664e4e55471061af0eaa798d40/src/base58.cpp),  generalized for variable length alphabets.