Patent ID: 8448251

Claim:
A data processing apparatus comprising: at least one processor; a display for displaying data processed by said at least one processor; at least one display buffer for storing an array of display elements for subsequent output to said display, said display elements being secure display elements for displaying secure data and non-secure display elements; a display controller for controlling display of data output from said at least one display buffer: a user interface, wherein said at least one processor is configured to execute at least one untrusted process and at least one secure process, said at least one secure process having access to secure data; a secure user interface for receiving a user input, said data processing apparatus configured such that said user input received at said secure user interface is transmitted either via a hardware link to said display controller or via a hardware link to a secure processor configured to execute only secure processes wherein said received user input is not accessible to said at least one untrusted process; and said data processing apparatus being responsive to an input received at said secure user interface to transform data to be displayed on said display such that said secure display elements and said non-secure display elements are transformed differently to each other.