Content item encryption on mobile devices

Patent metadata

Field	Value
Publication number	US-10204235-B2
Application number	US-201615195330-A
Country	US
Kind code	B2
Filing date	Jun 28, 2016
Priority date	Feb 9, 2014
Publication date	Feb 12, 2019
Grant date	Feb 12, 2019

Abstract

Applications are stored on removable storage of a mobile device in an encrypted form to provide isolation and piracy protection. In one implementation, each application is encrypted using its own associated encryption key that is generated based on an identifier of the application and a master key that is associated with a trusted platform module of the mobile device. In another implementation, each application is encrypted using two associated encryption keys. One key is used to encrypt binary data associated with the application such as source code, and the other key is used to encrypt application data such as graphics and configuration files. The encryption keys are each generated using the identifier of the application, the master key, and identifiers of the folders where the corresponding data types are stored on the mobile device. The removable storage includes SD cards formatted using the FAT or exFAT file systems.

First claim

What is claimed:

1. A method comprising:
receiving a request to write data to a region of removable storage of a mobile device, wherein the region of removable storage is associated with a content item;
determining, by the mobile device, that the request is authorized;
in response to determining that request to write the data is authorized, generating a content item key associated with the content item by the mobile device based on a master key signed by a trusted platform module associated with the mobile device and an identifier associated with the content item;
determining a region of non-removable storage of the mobile device;
storing the content item key in a region of non-removable storage of the mobile device;
encrypting the data using the key by the mobile device; and
storing the encrypted data in the region of removable storage associated with the content item by the mobile device.

2. The method of claim 1 , wherein the removable storage comprises a secure digital card.

3. The method of claim 1 , wherein the content item is one or more of an application, a video content item, or an audio content item.

4. The method of claim 1 , wherein generating a content item key associated with the content item comprises determining the master key associated with the mobile device.

5. The method of claim 4 , wherein the master key is stored in the region of non-removable storage associated with the mobile device.

6. The method of claim 1 , further comprising storing the generated key in a cache.

7. The method of claim 1 , wherein the mobile device comprises at least one of a cell phone or a tablet computer.

8. A system comprising:
removable storage of a mobile device;
non-removable storage of the mobile device; and
a file manager configured to:
receive a request to write data to a region of the removable storage of the mobile device, wherein the region of removable storage is associated with a content item;
determine that the request to write the data is authorized;
in response to determining that request to write the data is authorized, generate a content item key associated with the content item device based on a master key signed by a trusted platform module associated with the mobile device and an identifier associated with the content item;
determine a region of the non-removable storage of the mobile device;
store the content item key in a region of non-removable storage of the mobile device;
encrypt the data using the key; and
store the encrypted data in the region of removable storage associated with the content item.

9. The system of claim 8 , wherein the removable storage comprises a secure digital card.

10. The system of claim 8 , wherein the content item is one or more of an application, a video content item, or an audio content item.

11. The system of claim 8 , wherein generating a content item key associated with the content item comprises determining master key associated with the mobile device.

12. The system of claim 11 , wherein the master key is stored in the region of non-removable storage associated with the mobile device.

13. The system of claim 8 , wherein the file manager is further configured to store the generated key in a cache.

14. The system of claim 8 , wherein the mobile device comprises at least one of a cell phone or a tablet computer.

Assignees

• Microsoft Technology Licensing Llc

Inventors

• Callaghan David
• Pudipeddi Ravisankar
• Olsen Geir
• Patel Sachin
• Zhou Jianming
• D'Silva Dylan

Classifications

• G06F2221/0704

  Physics · mapped topic

• G06F21/6218 Primary

  to a system of files or objects, e.g. local or distributed file system or database · CPC title

• G06F21/10 Primary

  Protecting distributed programs or content, e.g. vending or licensing of copyrighted material (protection in video systems or pay television H04N7/16) {; Digital rights management [DRM]} · CPC title

• G06F21/1011 Primary

  to devices · CPC title