encode32

encode32

This is a Base-32 encoding for 32-bit numbers inspired by Douglas Crockford

http://www.crockford.com/wrmg/base32.html

This encoding is designed to balance compactness with human-friendliness and robustness. It uses 32 digits, the standard numbers and 22 alphabetic characters. It is case insensitive and characters easily confused by humans are accepted as aliases for some digits (e.g. l and I for 1, o for 0, etc). U is excluded so you can avoid winding up with certain common obscenities.

A 32-bit unsigned integer will encode into 7 base-32 (5-bit) digits (left padded with 0 as needed). Rather than use an additional check character as suggested in the original source, we fill the otherwise unused bits of the final character to with a 3-bit parity checksum. This feature makes it incompatible with other encoding schemes, but allows for quick sanity checks for transcribed numbers without the increased length or additional alphabet required by Crockford's "mod 37 checksum" approach.

Install

npm install encode32

or

git clone http://github.com/femto113/node-encode32.git
cd encode32
npm link

Example

var enc = require("./encode32");

var a = enc.encode32(123456772);
// a == "0XDWT16"

// can change case or substitute 1's and 0's without problem
var b = [
  "0xdwt16", // lower case
  "oXDWTi6", // o for 0 and i for 1
  "OxDwtL6"  // O for 0 and L for 1
].map(function (s) { return enc.decode32(s); });
// b == [123456772, 123456772, 123456772]

// but break the parity check and you get NaN
var c = [
  "0XDWT18", // incorrect final digit
  "X0DWT16", // transposed digits
  "0XDT16"   // missing digit
].map(function (s) { return enc.decode32(s); });
// c == [NaN, NaN, NaN]

console.log(a, b, c);

TODO

• needs performance work (probably should port to C++)
• should provide versions without parity bits and with checksum for compatibility with other implementations