dmhendricks/hash-int

A PHP class to generate a short hash from an integer.

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Details

github.com/dmhendricks/hash-int

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Installs: 44

Dependents: 0

Suggesters: 0

Security: 0

Stars: 2

Watchers: 3

Forks: 0

Open Issues: 0

1.0.0 2018-10-09 18:56 UTC

Requires

  • php: >=4.0.4

MIT 1022c060bc6eec9a7cf762e58365db7d669ae54a

This package is auto-updated.

Last update: 2024-10-14 07:00:23 UTC

README

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Hash Integer

A PHP class to generate an alphanumeric hash of specified length from an integer.

composer require dmhendricks/hash-int

Requirements

  • PHP 5.6 or higher
  • BC Math: apt install php7.x-bcmath

Usage

$num = 456;

/**
 * Create a 7-character hash from integer
 */
$hash = \CloudVerve\HashInt::hash( $num, 7 );

// Unhash the string
$unhashed = \CloudVerve\HashInt::unhash( $hash );

echo 'Hashed: ' . $hash . '<br />';
echo 'Unhashed: ' . $unhashed;

Result

Hashed: p3Wq1aC
Unhashed: 456

Original Author Notes

Paraphrased (source):

I wanted a short, unique, alphanumeric hash with a sequence that is difficult to deduce. I could create it with md5 and trim the first n chars, but storing a truncated checksum in a unique field means that the frequency of collisions will increase geometrically as the number of unique keys for a base 62-encoded integer approaches 62^n. I'd rather do it right than create a time bomb.

Base 62

Hashes are base 62 encoded base 10 integers. 1=1, 10=a, 36=Z, 61=z, 62=10, 72=1a, etc.

62, 3844, 238328, 14776336, 916132832, 56800235584, 3521614606208

1 character = 62 permutations, 2 characters = 3844 permutations, etc.

41, 2377, 147299, 9132313, 566201239, 35104476161, 2176477521929

41 = next highest prime from golden mean of 62.

2377 = next highest prime from golden mean of 3844.

Uniqueness

I chose to use primes to ensure hash uniqueness. Any prime greater than one half 62^n will do, but if you use a prime near 62^n or 62^n/2 or 2*62^n/3 etc, you will detect a linearity in the sequence at certain points in the ring.

Appearance of Randomness

I chose primes near the golden ratio to maximize the appearance of randomness. Given a small set of hashes (even with the associated id) it would be difficult for anyone to guess the next hash.

⚠️ Minimum-Security Technique

This is a thin rotation and base re-encoding obfuscation algorithm, not an encryption algorithm. Don't use this to encrypt sensitive information - use it to obfuscate integer IDs or create short reference keys (as an example, for short URLs).

Special Thanks

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