Autonomous Trust and Zero-Knowledge Blockchain Framework for Secure Federated Training of Medical Foundation Models

The tremendous progress of medical foundation models has proven to be groundbreaking in meta-analysis of clinical prediction, diagnosis, and multimodal healthcare analytics, but the development of medical foundation models is limited due to stringent data privacy concerns, cross-institutional trust issues, and security risks in a collaborative learning environment. Traditional federated learning allows for distributed training of the model with no central sharing of data but is prone to poisoning of the model, inference attacks, and low verifiability of participating institutions. This study proposes an idea of Autonomous Trust and Zero-Knowledge Blockchain Framework (AT-ZKBF) for Federated Medical Foundation Models, to establish decentralized trust, cryptographic verifiability and secure collaboration among heterogeneous healthcare providers. The framework combines the foundation model training in a federated peer-to-peer setup, the permissioned blockchain network for trust orchestration and mechanisms using the zero-knowledge proof (ZKP) for model updates to avoid the content of sensitive parameters of the model. Every local update is cryptographically authenticated with zk-SNARK-based zero-knowledge proofs that check proper gradient descent running and limited limit on updates without exposing private gradients or data. A reputation-driven trust scoring module automatically scores the reliability of participants. Experimental evaluation done on a BraTs, a multi-institutional medical imaging dataset shows that the proposed framework can get 96.4% classification accuracy (up 4.8% vs. standard federated learning) with poisoning model control decreased by 63% and communication overhead reduced by 21% by optimized blockchain batching. Security analysis makes sure of the robustness from gradient inferences and Byzantine attacks. The validation upon integration of autonomous trust computation, and zero-knowledge cryptography to blockchain enabled federated learning substantially adds to security, transparency and scalability for collaborative medical foundation model training providing a probable way forward to privacy preserving trust worthy AI in healthcare ecosystems.