Lost and Found in the Fog of Trust
summary
Protocol promises private computation of the size of the intersection between Victor’s trusted keys and Peggy’s witnesses, but formalization finds two attacks that completely break privacy. One attack uses Victor cheating with per-key blinding to link entries after double-blinding; the other exploits the BLS instantiation so colluding Walters who reveal their private keys let Peggy recover gamma^b and hence identify trusted members. The protocol is implemented and analyzed and currently unfixable.
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chapters (7)
- 0:00Fog of Trust protocol intro
- 1:47Motivation behind protocol
- 3:36How protocol works
- 6:26Formal verification flaws
- 7:31First privacy attack
- 8:58BLS signature exploit
- 14:38Protocol flaws summary
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