日前一家公司通知我去参加上岗培训，交费400块。说培训完考过试后归还，交钱是因为怕我们泄漏公司机密信息。我不知道这种做法是否合理？愿听大家指教。

they promised to give us the receipt once we handed S$400. They claimed the money is for candidates to attend the course everyday(5-day course), if you miss one lesson, the 400 deposit will not be returned. They said the company paid for the course and lecturer, so all the candidates must make sure to attend it every day. After the course there is a test, if you pass the test you'll be offered the job. Do this credible?

只是参加培训，公司需要我们每天都听课，缺课的话也扣押金。