Introduction to Verifiable Delay Functions (VDFs) with Joseph Bonneau | a16z crypto research talks
Source: YouTube · a16z crypto · published Jul 30, 2022 · 57:32
VDFs are cryptographic primitives designed to enforce a specific sequential computation time, solving randomness bias by preventing attackers from calculating outcomes within a submission window 0:2913:06.
Key Takeaways:
• Traditional random beacons suffer from a "last revealer" attack where a malicious party aborts if the outcome is unfavorable, a problem VDFs can mitigate 6:33.
• A VDF requires three properties: verifiability (efficient checking), sequential delay (unskippable steps), and uniqueness (single output) 19:4421:59.
• Modern constructions use iterated modular square roots where a proof is generated in parallel to forward computation, allowing fast verification 29:44.
• RSA-based VDFs rely on squaring in an unknown order group, utilizing proofs like Wesolowski's for constant-size verification 35:0137:02.
By enforcing time-based delays, VDFs enable secure distributed randomness without the need for complex punishment mechanisms or trusted setups 10:5013:22.
Sources:
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First 800 characters of the transcript
uh so welcome to this afternoon's um a6 crypto research seminar uh very happy um that we'll be having jovano just joined as a research partner the research team uh last week and he's going to be telling us about a very important cryptographic primitive which he co-invented verifiable delay functions so joe it's all yours this talk is going to be as tim said about uh vdfs and a slightly more broad theme of time-based crypto um so just to position what's kind of interesting about this uh whole field like traditionally in crypto uh you know there's things that we want to be as fast as possible everything that honest parties do like encrypt things decrypt things sign things um and then there are a bunch of problems that we hope are intractable as slow as possible so you know brute forcing a ke…