Patent · US Active

Method and apparatus for maintaining secure time

US9292712B2 · kind B2 · utility

3Cited by

4References

24Claims

0Family size

Assignee

ST-ERICSSON SA · CH

Inventors

Per Ståhl · Klagshamn, SE
Håkan Englund · Lund, SE
Martin Hovang · Bjärred, SE
Herve Sibert · Le Mans, FR

Key dates

Filing date	Sep 28, 2012
Grant date	Mar 22, 2016
Priority date	—
Expiry date	Jan 14, 2034

Classification

Technology area (CPC G)Physics
CPC primaryG06F21/74
WIPO fieldComputer technology
WIPO sectorElectrical engineering

Abstract

An exemplary method of maintaining secure time in a computing device is disclosed in which one or more processors implements a Rich Execution Environment (REE), and a separate Trusted Execution Environment (TEE). The TEE maintains a real-time clock (RTC) that provides a RTC time to the REE. A RTC offset is stored in non-volatile memory, with the RTC offset indicating a difference between the RTC time and a protected reference (PR) time. Responsive to a request from the REE to read the RTC time, a current RTC time is returned to the REE. Responsive to a request from the REE to adjust the RTC time, the RTC time and the corresponding RTC offset are adjusted by a same amount, such that the PR time is not altered by the RTC adjustment. An exemplary computing device operable to implement the method is also disclosed.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.