Anthropic open-sources FlashProve, a zero-knowledge prototype that proves a response came from committed model weights
Confirmed
The takeaway
On Nov 2, 2026 (X announcement Nov 3) Anthropic published FlashProve, an Apache-2.0 zkSNARK prototype that lets a verifier check that a model’s output came from a specific committed set of weights without seeing them.
Status
- Claim
Confirmed
- Our reporting
- High confidence
- Importance
- 3 of 5
- Last verified
- 4 November 2026
Your AI and this story
- GPT-6 Astra186 days after its cutoff
- Claude Opus 5.5125 days after its cutoff
- Gemini 4 Argon216 days after its cutoff
- Grok 4.7155 days after its cutoff
None of these four assistants can know about it. The closest, Claude Opus 5.5, stops 125 days before it.
Key facts
- Model tested: Llama 4 Maverick (400B MoE, ~17B active), third-party 4-bit conversion
- Proving ~110 tokens/s on one H100; proof ~19 MB per 1,024-token request; verification ~17 s on a 24-thread CPU
- Overhead: roughly 70–95x the GPU time of serving the model on vLLM
- Protocol properties (completeness, soundness, zero knowledge) proven in Lean; the fast C++ verifier is not formally verified
- Limits: integer model under greedy decoding only, 1,024-token context, architecture not hidden, side channels out of scope
- Anthropic’s X post: 462k views (fxtwitter, Nov 4)
What happened
Anthropic’s research page describes FlashProve as “an open-source performant prototype for provable inference.” The provider publishes a commitment to its weights once; afterwards it produces proofs for batches of requests, and anyone holding the commitment can check them without the weights. Anthropic’s X post names two uses: making it harder to hijack a chat, and letting safety evaluators confirm that the model they tested is the one served to customers.
Why it matters
Evaluators and governments have had no way to check that the deployed model is the audited one. The prototype is far from production cost (70–95x GPU time, short contexts, greedy decoding only), and Anthropic presents it as research, not a product.
Sources
4 sources from 4 sites. Numbers match the chips in the text.
4 sources: 3 primary, 1 press
Primary
- Anthropic: Provable inference (FlashProve)anthropic.com, official
- FlashProve code (GitHub, Apache 2.0)github.com, code
- Anthropic on X (Nov 3)x.com, official
Press
- TechCrunch: Anthropic is working on a system to prove AI models’ identitytechcrunch.com, press
Changes
- Filed