🤖 AI Summary
"This study addresses the inadequacies in version management and verification within collaborative document editing for blockchain-based notarization. It proposes a fluid notarization model that treats the document's evolution as the object of notarization. By employing JSON-native delta-CRDTs, the model constructs a causal evolution graph, with identifiers of these graphs recorded on the blockchain to ensure the independent verifiability of document changes. The combination of CRDTs' deterministic convergence and the audit evidence provided by the blockchain enables notarization of the document's evolution rather than a single state. The effectiveness and advantages of this approach are validated through a prototype for collaborative editing of electronic health records."
📝 Abstract
Traditional blockchain-based document notarization follows a snapshot-oriented model in which each document revision is represented as an independent state anchored on-chain through a cryptographic reference. While effective for immutable artifacts, this approach becomes inadequate when documents evolve through collaborative editing. Concurrent modifications create divergent document versions that must be reconciled outside the notarization layer, while even minor changes require generating and distributing new document snapshots. Conversely, collaborative replication frameworks such as CRDTs provide deterministic reconciliation of concurrent updates, but do not inherently provide independently verifiable evidence of when contributions were published. This paper introduces Fluid Notarization, a notarization paradigm in which document evolution itself becomes the object of notarization. Rather than certifying isolated states, Fluid Notarization certifies a graph of causally related evolution artifacts generated by a JSON-native delta-CRDT. The proposed model builds upon Melda, which represents document changes as compact, content-addressed deltas linked through causal dependencies. Blockchain notarization is reduced to recording identifiers of these evolution artifacts, while synchronization, reconstruction, and conflict resolution remain entirely off-chain. The resulting architecture combines two complementary guarantees: deterministic convergence provided by the CRDT and independently auditable proof-of-existence, provenance, and publication evidence provided by the blockchain. A prototype implementation and validation scenario based on collaboratively edited electronic health records demonstrate the feasibility of the approach and highlight the advantages of notarizing document evolution rather than successive document snapshots.