Hash check failed. Key file seems to be corrupted. (0)

[khoavm]

Help me this is my code. key file same folder with index.php
""""""""""""

require 'vendor/autoload.php';
use baibaratsky\WebMoney\Signer;

Flight::route('/', function(){
$test = file_get_contents('test.kwm');
$signer = new Signer('wmid', $test, '12345678');
$data = 'Data to be signed';
$signature = $signer->sign($data);
echo "hello world! $signature";
});

Flight::start();