Abstract: One aspect of the invention provides a method of controlling execution of a computer program. The method comprises the following runtime steps: parsing code to identify one or more indirect branches; creating a branch ID data structure that maps an indirect branch location to a branch ID, which is the indirect branch's equivalence class ID; creating a target ID data structure that maps a code address to a target ID, which is an equivalence class ID to which the address belongs; and prior to execution of an indirect branch including a return instruction located at an address: obtaining the branch ID associated with the return address from the branch ID data structure; obtaining the target ID associated with an actual return address for the indirect branch from the target ID data structure; and comparing the branch ID and the target ID.

Abstract: An icon for a machine recognition system has a frame element and a symbol associated with the frame element. The icon can be defined by a model-collection of frame keypoints. The icon can be recognized by identifying an image-collection of frame keypoints within the image that matches the model-collection of frame keypoints and by recognizing a symbol associated with the image-collection of keypoints that is identified.

Abstract: A tamper response mechanism introduces a delayed failure into a program in response to detected tampering with the program. The mechanism determines a manner of responding to the detected tampering. The manner of responding may include corrupting a global pointer or using other techniques. The mechanism also determines when to respond to the tampering and implements the response at the determined time.

Abstract: A tamper response mechanism introduces a delayed failure into a program in response to detected tampering with the program. The mechanism determines a manner of responding to the detected tampering. The manner of responding may include corrupting a global pointer or using other techniques. The mechanism also determines when to respond to the tampering and implements the response at the determined time.