protected function clientSignature(Request $request): string
    {
        $signature = '';
        foreach (static::SIGNATURE_HEADERS as $header) {
            $signature .= $request->getHeaderLine($header) . ';';
        }

        return hash('sha256', $signature);
    }
protected function clientSignature(Request $request): string
    {
        $signature = '';
        foreach (static::SIGNATURE_HEADERS as $header) {
            $signature .= $request->getHeaderLine($header) . ';';
        }

        return hash('sha256', $signature);
    }
protected function clientSignature ( Request $ request ) : string { $ signature = '' ; foreach ( static :: SIGNATURE_HEADERS as $ header ) { $ signature .= $ request -> getHeaderLine ( $ header ) . ';' ; } return hash ( 'sha256' , $ signature ) ; }
Must return string which identifies client on other end. Not for security check but for
session fixation.

@param Request $request
@return string
Must return string which identifies client on other end . Not for security check but for session fixation .