Anthropic has unveiled FlashProve, an open-source cryptographic system designed to verify whether an AI model actually generated a response without revealing its proprietary weights, which could help users, independent auditors and regulators confirm that providers are running the models they claim to serve. The system uses zero-knowledge cryptography to generate mathematical proofs that a specific model produced given output tokens in response to a particular prompt, addressing a trust problem as companies increasingly rely on third-party model providers and routing services. FlashProve uses a zero-knowledge succinct non-interactive argument of knowledge (zkSNARK), with providers publishing a cryptographic commitment to model weights and then generating a proof that the committed model produced the corresponding output tokens; anyone with the commitment, prompt and response can verify the proof without accessing the model weights. Anthropic demonstrated the approach using Llama 4 Maverick, a 400-billion-parameter mixture-of-experts model; running on a single NVIDIA H100 GPU, FlashProve generated proofs at approximately 110 tokens per second, with each proof measuring around 19 MB for a 1,024-token request, and verification takes approximately 17 seconds using a 24-core CPU without requiring a GPU. Anthropic believes cryptographic inference proofs could help detect tampering with model responses, support independent evaluations and give regulators a way to verify which models providers are serving. However, FlashProve remains a research prototype rather than a production-ready solution, and generating proofs requires substantially more computing resources than ordinary inference,