Generate hash using PHASH with PHP

Question

How can I generate a PHASH value from a string in PHP ?

I've inherited an ASP codebase that utilizes PHASH with strings ( not paths to images ). From research, PHASH is used for images.

I'm currently rewriting this part of the codebase using PHP , and there's a couple of libraries that seem useful:

• https://github.com/jenssegers/imagehash
• https://github.com/xwiz/phash/blob/master/phash.php

However , they both require a path to an image. I've tried jenssegers/imagehash and this throws an exception when I pass a random string.

Code below of how PHASH is currently used within the legacy codebase:

sLoginPassword = RequestValue("Password")
SQLVal(PHASH(sLoginPassword))

Update

PHASH is a custom function within the codebase, I failed to find it originally due to mixed casing ( PHash vs PHASH ).

Luckily I found the following SO answer which is written in C# . Thanks to @Lathejockey81 for provding the answer, I've converted this into PHP below (as an answer).

Answer 1

Custom PHASH function converted from SO answer :

function PHASH($string)
{
    $value = trim(strtoupper($string));

    $dAccumulator = 0;
    $asciiBytes = [];

    for($i = 0; $i < strlen($value); $i++) {
        $asciiBytes[] = ord($value[$i]);
    }

    for($i = 0; $i < count($asciiBytes); $i++) {
        if(($i & 1) == 1) {
            $dAccumulator = cos($dAccumulator + (float) $asciiBytes[$i]);
        } else {
            $dAccumulator = sin($dAccumulator + (float) $asciiBytes[$i]);
        }
    }
    $dAccumulator = $dAccumulator * pow(10, 9);

    return round($dAccumulator);
}