base32-crockford

Base 32 encoding/decoding for JavaScript

Base 32 is between hexadecimal notation and Base 64 encoding. It's intended to be a human-friendly -- you don't have to worry about punctuation, capitalization, or letters/numbers that are easy to confuse, making it easier to transmit in handwriting or over the phone.

One of the primary purposes is to have aesthetically pleasing SHA1 hashes. Compare:

• Hex: 17O57684bea1f9331418b633a8f373119d765fd4
• B64: xE_ptB5SeclHm8JEsD0-ST1mTBM
• B32: 2w2qd15ym7wk650rprtuh4vk26eqcqym

Try giving out the Base 64 hash over the phone! "lowercase 'x', capital 'E', underscore, lowercase 'p', ..." Base 32 will work the same with upper- or lowercase, you can mistake a number for a similar-looking letter, and it will still decode to the same data.

Getting started

In your shell, install with npm:

npm install base32

In your code:

var base32 = require('base32')

// simple api

var encoded = base32.encode('some data to encode')
var decoded = base32.decode(encoded)

// streaming api
this.encoder = new Base32.encoder()
this.dataCallback = function(chunk) {
    this.emit(this.encoder(chunk))
}
this.closeCallback = function(chunk) {
    this.emit(this.finish()) // flush any remaining bits
}

// easy sha1 hash
var hash = base32.sha1(some_data_to_hash) // DONE.

On the command-line (to install system-wide, use npm install -g base32):

base32 -h
#> Usage: base32 [input_file] [-o output_file] [-d|--decode] [-s|--sha]
echo "Hello World" | base32
#> 91jprv3f41bpywkccg50
echo 'axqqeb10d5u20wk5c5p6ry90exqq4uvk44' | base32 -d
#> Wow, it really works!
base32 -s test/*
#> ky2t1raumjn9cghne773petngx3zz3q7  test/base32-test.coffee
#> 6b4bkjaveddmg5jh7hnyw132yht20g6e  test/compare.coffee

Warning: this is a Base 32 implementation, not the Base 32 implementation

There are about (128 choose 32) different specifications of something called "Base 32" - see Wikipedia for some of them.

This is just one that should be simple, less error-prone, and streamable (for Node).

Minispec

• The encoding alphabet consists of the numerals 0-9 and the letters a-z, excluding a few letters that might look like numbers, which we simply interpret as follows:

  • I -> 1
  • L -> 1
  • O -> 0
  • S -> 5

• When decoding, capital letters are converted to lowercase and the "ambiguous" letters mentioned above converted to their numeric counterparts.

• Each character corresponds to 5 bits of input.

• Lexicographic order of strings is preserved through Base 32 encoding.

Formalia

Under MIT License.

Fork as much as you like, I'm more than amenable to pull requests. I'm trying to keep it reasonably node-ish, so bear that in mind.