Access control for selected document contents using document layers and access key sequence
US9990474B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 16, 2016 |
| Grant date | Jun 5, 2018 |
| Priority date | — |
| Expiry date | Sep 9, 2036 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2209/603
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
In a digital rights management system, layers are defined for each document and user permissions are specified for each layer, to control user access at the layer-level. The layers are ordered by depth, where a layer completely contained inside another layer is deemed deeper than the other layer. The layers are encrypted in a deep-to-shallow order, each by its own encryption key. The entire document is then encrypted. When a user requests access to a document, the system generates an ordered sequence of encryption keys based on the user's access rights for each layer. The document open program on the user's client computer attempts to decrypt the various layers using the ordered sequence of keys. The client program and the system's key sequence generating algorithm are designed to give the result that only layers that the user has access to are successfully decrypted and displayed at document open time.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.