Authentication today mostly means using passwords or personal identification numbers (PINs). The average user has to remember an increasing amount of PINs and passwords. But unfortunately, humans have limited capabilities in remembering abstract alphanumeric sequences. Thus, many people either forget them or use very simple ones that imply several security risks. In our previous work on PIN entry on ATMs (cash machines), we found out that many persons support their memory recalling PINs by using an imaginary shape overlaid on the number pad. In this paper, we introduce PassShape, a shape based authentication mechanism. We argue that using shapes will allow more complex and more secure authentication with a lower cognitive load. That is, it enables people to use easy to remember but complex authentication patterns.