Tracking responsibilities in collaborative IFC modelling: Revision-Safe Signing using IFC5 modularisation.

Collaborative building design with BIM consolidates discipline-specific information in shared models, yet current open BIM exchange using monolithic IFC files lacks mechanisms for attributing and preserving responsibility at the level of individual information items. This paper introduces a methodology for cryptographically signing discipline-specific information and properties in IFC5 model layers, using an Entity Component System (ECS) and canonical Javascript Object Notation (JSON) serialisation, enabling independent authorship, digital signing, and integration without loss of provenance. The methodology is prototypically implemented and validated in a web-based platform, which supports annotation of IFC5 models, cryptographic signing (Ed25519), and verification of whether model properties have been altered by checking their signatures. Demonstrated for architectural and fire safety planning in Germany , the results show that granular, revision-safe signatures enable transparent and auditable assignment of responsibilities in collaborative BIM processes.