A RIB validation rule, could be used with Laravel ^5.5 or separately

RIB.php

<?php

namespace App\Rules;

use Illuminate\Contracts\Validation\Rule;
/**
 * RIB validation (valide in morocco only)
 * 
 * @author med-ezzairi
 *
 */
class RIB implements Rule
{
    
    private $lastError = '';
    
    /**
     * Create a new rule instance.
     *
     * @return void
     */
    public function __construct()
    {
        //
    }

    /**
     * Determine if the validation rule passes.
     *
     * @param  string  $attribute
     * @param  mixed  $value
     * @return bool
     */
    public function passes($attribute, $value)
    {
        return $this->checkRIB( $value );
    }

    /**
     * Get the validation error message.
     *
     * @return string
     */
    public function message()
    {
        //return 'The :attribute must be something here to describe the eror.';
        return trans('validation.rib_format');
    }
    
    /**
     * Verify the integriry of RIB
     *
     * @param string $rib
     * @return boolean
     */
    private function checkRIB( $RIB = null )
    {
        
        $matchedInfo = null;
        preg_match( '/^(\d{3})(\d{3})(\d{4})(\d{5})(\d{5})(\d{2})(\d{2})$/', $RIB, $matchedInfo );
        if( empty( $matchedInfo ) ){
            $this->lastError = "Format du RIB est invalide";
            return false;
        }
        
        $banque		= $matchedInfo[1];
        $city		= $matchedInfo[2];
        $poste		= $matchedInfo[3];
        $identity	= $matchedInfo[4];
        $account	= $matchedInfo[5];
        $rang		= $matchedInfo[6];
        $key		= $matchedInfo[7];
        //--
        $C1 = (($banque * 1000 + $city) % 97);
        $C2 = (($C1 * 10000 + $poste) % 97);
        $C3 = (($C2 * 100000 + $identity) % 97);
        $C4 = (($C3 * 100000 + $account) % 97);
        $C5 = (($C4 * 100 + $rang) % 97);
        $C6 = (($C5 * 100) % 97);
        $new_key = 97 - $C6;
        if( $new_key == $key ){
            return true;
        }
        $this->lastError =  "RIB invalide";
        return false;
    }
}