Anthropic Releases FlashProve: Cryptographic Proofs That a Reply Came From Committed Weights

Anthropic’s Frontier Red Team has released FlashProve, an open-source research prototype for provable inference.

FlashProve is a zkSNARK system from Anthropic that proves a reply came from a committed model.

The proof reveals nothing about the model weights.

On Llama 4 Maverick, a 400B mixture-of-experts model, it proves about 110 tokens/second on 1 H100.

For developers, this targets a real gap: today you cannot check which model actually answered your API call.

TL;DR Size: Proves a 400B MoE model (~17B active per token); context capped at 1,024 tokens per request.

Runs on: Prover needs 1 H100 80 GB, 24 CPU cores and ~290 GB host RAM.

Verifier runs on a CPU, no GPU.

Performance: Orders of magnitude faster than prior open-source zkML systems on the same 400B model.

Best: 110 tokens/second proving on 1 H100, with 18.78 MB proofs checked in 17 seconds.

Worst: Proving costs ~70 to 95x the GPU time of plain vLLM inference.

What problem does provable inference solve?

A user querying a model cannot verify which model produced the response.

A routing service could swap in a cheaper model.

An attacker could tamper with the token stream.

Judging from output quality alone is unreliable.

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