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Anthropic releases FlashProve to check which model produced a reply

Anthropic published FlashProve on 2 November 2026, an open research prototype intended to cryptographically verify that a reply matches the computation of a specified model without revealing its internal parameters.

The provider first commits to the model parameters, then supplies a verifiable proof of the computation. This assurance concerns execution; it does not prove that the generated information is true.

Costs remain high. Anthropic reports roughly 70–95 times the reference inference GPU time in its test on quantised Llama 4 Maverick. These are the team's measurements, with no independent validation established.

Code and documents carry the Apache 2.0 licence. The documentation says the programs have not undergone an independent security audit; formal guarantees for the Lean verifier do not automatically extend to the fast C++ verifier. This remains intermediate research progress.

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