Cas provides similar functionality to the myproxy service in that it returns a gsi - based credential to the portal or other client when presented with an appropriate username password combination , but it enables more fine - grain authorization than the standard myproxy credentials Cas为myproxy服务提供了类似的功能,其中以适当的用户名/密码组合形式向门户或其他客户机返回基于gsi的证书,不过这样实现的身份验证粒度比标准的myproxy证书更加精细。