Talk by Alex Lombardi (Princeton University)
summary
Provides a concrete path for when Fiat–Shamir is provably safe in the standard model: if the starting protocol has information-theoretic soundness and the hash family satisfies correlation intractability for the protocol’s bad-challenge relation, then Fiat–Shamir yields a sound non‑interactive argument. Shows constructions (LWE → functions; Peikert–Shiehian improvements; product‑relation work) and a flowchart of options, but warns of counterexamples, the need for statistically binding commitments/trapdoors, and that secure hash evaluation sometimes must be slower than the functions it protects.
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chapters (8)
- 0:00Introduction to Fiat-Shamir
- 1:51Interactive proof systems
- 7:25The Fiat-Shamir transform
- 10:58Security of Fiat-Shamir
- 15:18Correlation intractability
- 24:55Proving soundness
- 43:27CI construction challenges
- 52:38Restricted constructions
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