Trusted Browsers for Uncertain Times
summary
JavaScript can recover fine-grained time even when performance.now is rounded coarsely; the clock edge technique and other tactics boost effective resolution by up to two orders of magnitude (100 ms → ~0.5–1 ms). Browsers expose many implicit clocks (video subtitles, animations, Web Speech, etc.) that leak timing. A Fuzzyfox prototype implements Fermata-style fuzzy time: randomized pauses and queued I/O that break timing edges, measurably noisy clocks and reduced attack bandwidth at the cost of higher latency for large sequential loads.
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chapters (20)
- 0:00Intro
- 1:02Browsers and timing attacks
- 1:58Timing attacks in web browsers SVG Filter cross-origin pixel stealing
- 2:33What is being done about it?-SVG attack
- 3:01What is being done about it? - Cache attack
- 4:06Rounding down the clock
- 5:57Clock-edge technique - performance.now()
- 7:21Implicit clocks - Techniques
- 8:53Implicit clocks - WebVTT and clock-edge
- 10:23Fuzzy time for the VAX security kernel • VAX VMM
- 10:48Fuzzy time - Problem
- 12:03Fuzzy time - Solution guarantees
- 12:35Fuzzy time - 1/0 queuing
- 13:52Fermata - Why adapt fuzzy time?
- 16:22Fuzzyfox - Main thread queuing
- 19:01Fuzzyfox - Effectiveness - Explicit - performance.now()
- 19:31Fuzzyfox - Effectiveness - Implicit - WebVTT clock
- 20:28Fuzzyfox - Performance - Micro benchmarks
- 21:13Fuzzyfox - Performance - Sequential loads
- 22:04Fuzzyfox - Performance vs Tor Browser
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