Showing papers by "Robert E. Tarjan published in 2003"

Establishing a secure channel with a human user

Abstract: A method of establishing a secure channel between a human user and a computer application is described. A secret unique identifier (“PIN”) is shared between a user and an application. When the user makes a request that involves utilizing the PIN for authentication purposes, the application renders a randomly selected identifier. The randomly selected identifier is in a format that is recognizable to a human but is not readily recognizable by an automated agent. The randomly selected identifier is then presented to the human user. The user identifies the relationship between the randomly selected identifier and the PIN. If the user's input reflects the fact that the user knows the PIN, then the user is authenticated.

Dynamic rectangular intersection with priorities

Abstract: We present efficient data structures to maintain dynamic set of rectangles, each with priority assigned to it, such that we can efficiently find the rectangle of maximum priority containing a query point. Our data structures support insertions and deletions of rectangles. In one dimension, when rectangles are intervals, our most efficient data structure supports queries and insertions in O(log n) time, deletions in O(log n loglog n) time and requires linear space. When intervals are guaranteed to be nonoverlapping (but one can be nested within the other) we obtain a simpler data structure that supports all operations in O(log n) time.

If Piracy Is the Problem, Is DRM the Answer?

Abstract: Piracy of digital content is considered a serious problem by content companies Digital Rights Management is considered a potential solution to this problem In this paper we study to what degree DRM can live up to this expectation We conclude that given the current and foreseeable state of technology the content protection features of DRM are not effective at combating piracy