Anthropic releases FlashProve, a prototype to prove which model answered

Anthropic has published FlashProve, an open-source research prototype that produces a cryptographic proof that a response came from a specific committed set of model weights, without revealing those weights. Today a user cannot check that a response came from the model a provider claims, rather than one swapped in by a routing service to save cost. In Anthropic's tests on Llama 4 Maverick, a single H100 GPU produced proofs at around 110 tokens a second, about 70 to 95 times the GPU time of normal inference, and each proof of about 19 MB took seconds to check on a CPU. Anthropic says it is sharing intermediate progress, not a finished system, and it currently handles contexts of only up to 1,024 tokens.