US Patent 11748504 Method for setting up a secure hierarchical referencing system

A performance-optimized secure hierarchical referencing system, for example to implement a cryptographic file system (CFS) in which files or other data are stored in a cryptographic tree structure on a untrusted environment. The system operates by using adaptive cryptographic access control (ACAC) whereby the data on the client (user) side is encrypted using keys. All said keys (with the exception of an entry key) are not stored but are calculated, and a dedicated symmetric key is used for each element in the referencing system (e.g. files, records, comments) to ensure that read/write permissions can be distributed to selected third parties at element level and actively revoked where required (sharing/revocation).