src/Client/ApiClient.php
private function signParams(array $params): string
    {
        ksort($params);

        $signature = '';
        foreach ($params as $name => $value) {
            $signature .= $name.$value;
        }
        $signature .= $this->sharedSecret;

        return md5($signature);
    }
private function signParams(array $params): string
    {
        ksort($params);

        $signature = '';
        foreach ($params as $name => $value) {
            $signature .= $name.$value;
        }
        $signature .= $this->sharedSecret;

        return md5($signature);
    }
@param array $params

@return string