Full Documentation

A small PHP class to generate YouTube-like ids from numbers. Read documentation at http://hashids.org/php

Installation

You can install Hashids thru Composer (packagist has hashids/hashids package). In your composer.json file use:

{
    "require": {
        "hashids/hashids": "^1.0"
    }
}

And run: php composer.phar install. After that you can require the autoloader and use Hashids:

require_once 'vendor/autoload.php';

use Hashids\Hashids;

$hashids = new Hashids('this is my salt');

Updating from v0.3 to 1.0?

Read the CHANGELOG!

Example Usage

The simplest way to use Hashids:

$hashids = new Hashids\Hashids();

$id = $hashids->encode(1, 2, 3);
$numbers = $hashids->decode($id);

var_dump($id, $numbers);

string(5) "laHquq"
array(3) {
  [0]=>
  int(1)
  [1]=>
  int(2)
  [2]=>
  int(3)
}

And an example with all the custom parameters provided (unique salt value, minimum id length, custom alphabet):

$hashids = new Hashids('this is my salt', 8, 'abcdefghij1234567890');

$id = $hashids->encode(1, 2, 3);
$numbers = $hashids->decode($id);

var_dump($id, $numbers);

string(5) "514cdi42"
array(3) {
  [0]=>
  int(1)
  [1]=>
  int(2)
  [2]=>
  int(3)
}

Curses! #$%@

This code was written with the intent of placing created ids in visible places - like the URL. Which makes it unfortunate if generated hashes accidentally formed a bad word.

Therefore, the algorithm tries to avoid generating most common English curse words. This is done by never placing the following letters next to each other:

c, C, s, S, f, F, h, H, u, U, i, I, t, T

Big Numbers

Each number passed to the constructor cannot be negative or greater than 1 billion by default (1,000,000,000). Hashids encode() function will return an empty string if at least one of the numbers is out of bounds. Be sure to check for that -- no exception is thrown.

PHP starts approximating numbers when it does arithmetic on large integers (by converting them to floats). Which is usually not a big issue, but a problem when precise integers are needed.

However, if you have either GNU Multiple Precision --with-gmp, or BCMath Arbitrary Precision Mathematics --enable-bcmath libraries installed, Hashids will increase its upper limit to PHP_INT_MAX which is int(2147483647) on 32-bit systems and int(9223372036854775807) on 64-bit.

It will then use regular arithmetic on numbers less than 1 billion (because it's faster), and one of these libraries if greater than. GMP takes precedence over BCMath.

You can get the upper limit by doing: $hashids->get_max_int_value(); (which will stay at 1 billion if neither of the libraries is installed).

Speed

Even though speed is an important factor of every hashing algorithm, primary goal here was encoding several numbers at once while avoiding collisions.

On a 2.26 GHz Intel Core 2 Duo with 8GB of RAM, it takes about:

1. 0.000093 seconds to encode one number.
2. 0.000240 seconds to decode one id (while ensuring that it's valid).
3. 0.493436 seconds to generate 10,000 ids in a for loop.

On a 2.7 GHz Intel Core i7 with 16GB of RAM, it takes roughly:

1. 0.000067 seconds to encode one number.
2. 0.000113 seconds to decode one id (and ensuring that it's valid).
3. 0.297426 seconds to generate 10,000 ids in a for loop.

Sidenote: The numbers tested with were relatively small -- if you increase them, the speed will obviously decrease.

Notes

• If you want to squeeze out even more performance, set a shorter alphabet. Hashes will be less random and longer, but calculating them will be faster.

Contact

I am on the internets @IvanAkimov

License

Hashids is licensed under The MIT License (MIT).