Simple php function to parse an image file and find if it has that image's signature (magic number) according to its extension

check_img_signature.php

<?php
// Author: Daniel L. Lacerda
// Created: 2018/10/05
// Updated: -
// License: MIT
/*
 * Reads the first bytes of the image file and checks its signature are true|false for that file extension
 *
 * @param actual $file
 * @param string $fileExtension
 * @return boolean
**/
function check_img_signature($file, $fileExtension) {
    
    $image_extensions = array("bmp"=>IMAGETYPE_BMP,"jpg"=>IMAGETYPE_JPEG,"jpeg"=>IMAGETYPE_JPEG,"png"=>IMAGETYPE_PNG,"gif"=>IMAGETYPE_GIF);
    
    //file extension is not in the list
    if ( !array_key_exists($fileExtension, $image_extensions) ) return false;
    
    //http://php.net/manual/en/function.exif-imagetype.php
    if (exif_imagetype($file) == $image_extensions[$fileExtension]) return true;
    
    return false;
}
?>