src/Didww/API2/ApiCredentials.php
protected function generateAuthString()
    {
        if (empty($this->password) || empty($this->userName)) {
            throw new ApiCredentialsException(" Undefined userName and/or password ");
        }

        $this->authString = $this->getTestMode() ? sha1($this->userName . $this->password . 'sandbox') : sha1($this->userName . $this->password);
    }
protected function generateAuthString()
    {
        if (empty($this->password) || empty($this->userName)) {
            throw new ApiCredentialsException(" Undefined userName and/or password ");
        }

        $this->authString = $this->getTestMode() ? sha1($this->userName . $this->password . 'sandbox') : sha1($this->userName . $this->password);
    }
method to generate authString property from userName and password properties
@throws ApiCredentialsException
@see http://open.didww.com/index.php/Authentication_Key