260 SEFM03 Tutorial T6 Jorge Cuellar Brisbane, Sep 2003 Preventing Resource Exhaustion: Delaying Commitment Idea: delay committing one's resources unt
{"Image DocumentName": "Cryptographic puzzles", "Image ImageDescription": "Used to protect against resource-exhaustion attacks. A server requires its clients to solve a puzzle, e.g. bruteforce search for some input bits of a one-way function, before committing its own resources to the protocol. The server can adjust the difficulty of the puzzles according to its load. Solving the puzzle creates a small cost for each protocol invocation, which makes flooding attacks expensive but has little effect on honest nodes. Drawbacks: IP layer does not know which node is the server (i.e. the respondent) MNs often have limited processor and battery capacity while an attacker pretending to be a MN is likely to have much more computational resources. The puzzle protocols work well only when all clients have approximately equal processing power. Brisbane, Sep 2003.", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}