Patent ID: 7464412

Claim:
A method for maintaining the security of a secured execution environment on a system comprising said secured execution environment and a second execution environment both on a single computing device, the method comprising: accepting at the second execution environment a flow of user input from a trusted input device; initially directing the accepted flow of user input from the second execution environment to the secured execution environment; determining at the secured execution environment whether said secured execution environment is in a standard input mode; subsequently directing the initially directed flow of user input at the secured execution environment based on the input mode of the secured execution environment including if said secured execution environment is in a standard input mode, transferring at least a first portion of said user input to said second execution environment; determining at the secured execution environment from the initially directed flow of user input at such secured execution environment whether said user input comprises a user NIM indication that said secured execution environment should be in a nexus input mode; and if said user input comprises said user NIM indication and said secured execution environment is not in said nexus input mode, switching said secured execution environment to said nexus input mode, said user NIM indication being the only way to initiate a transition from said standard input mode to said nexus input mode, there being at least two ways to transition from said nexus input mode to said standard input mode at least one of which is not a symmetrical counterpart of said user NIM indication.