Varying the amount of time that a mobile device must be inactive before the mobile device re-locks access to a computerized resource

1. A method of controlling access to a computerized resource of a mobile device, the method comprising:

sensing, by processing circuitry, a set of environmental factors from a particular environment of the mobile device when the mobile device unlocks the computerized resource in response to successful authentication of a user, wherein sensing the set of environmental factors includes detecting, via a microphone of the mobile device, whether the mobile device is in a vicinity of a familiar audio source;

selecting, by the processing circuitry, an expiration time based on the set of environmental factors, at least in part by choosing a relatively longer particular predefined time as the selected expiration time in response to the set of environmental factors indicating that the particular environment is a trusted environment and choosing a relatively shorter particular predefined time as the selected expiration time in response to the set of environmental factors indicating that the particular environment is not a trusted environment, and wherein the set of environmental factors indicate that the particular environment is a trusted environment when the mobile device is in a vicinity of the familiar audio source; and

configuring, by the processing circuitry, an inactivity timer to re-lock access to the computerized resource of the mobile device when the inactivity timer identifies a time period of mobile device inactivity that reaches the selected expiration time.

2. A method as in claim 1 wherein selecting the expiration time based on the set of environmental factors includes:

choosing, as the selected expiration time, a particular predefined time from multiple selectable predefined times.

3. A method as in claim 2 wherein configuring the inactivity timer to re-lock access to the computerized resource includes:

starting the inactivity timer;

wherein the inactivity timer, upon being started, (i) counts from an initial value to a predefined timeout value as a measure of a current amount of inactivity time, and (ii) provides a re-lock signal when the inactivity timer reaches the predefined timeout value.

4. A method as in claim 3 , further comprising:

resetting the inactivity timer to the initial value to restart the inactivity timer in response to user activity detected by the mobile device.

5. A method as in claim 3 , further comprising:

receiving the re-lock signal from the inactivity timer in response to the inactivity timer reaching the predefined timeout value, and

re-locking access to the computerized resource in response to the re-lock signal.

6. A method as in claim 3 , further comprising:

after the inactivity timer is started and before the inactivity timer reaches the predefined timeout value, sensing a new set of environmental factors from a new environment of the mobile device, and

selecting a new expiration time based on the new set of environmental factors; and

re-configuring the inactivity timer to re-lock access to the computerized resource of the mobile device when the inactivity timer reaches a new predefined timeout value corresponding to the new expiration time.

7. A method as in claim 6 wherein selecting the new expiration time based on the new set of environmental factors includes:

choosing, as the new expiration time, a new predefined time from the multiple selectable predefined times, the new predefined time being different from the particular predefined time;

wherein re-configuring the inactivity timer to re-lock access to the computerized resource includes:

directing the inactivity timer to measure the new expiration time in place of the selected expiration time and then re-starting the inactivity timer.

8. A method as in claim 7 , further comprising:

after the inactivity timer is restarted, detecting new user activity and re-starting the inactivity timer in response to the new user activity,

receiving the re-lock signal from the inactivity timer in response to the inactivity timer measuring a time period of mobile device inactivity that reaches the new expiration time, and

re-locking access to the computerized resource in response to the re-lock signal.

9. A method as in claim 7 wherein choosing the new predefined time includes:

selecting, as the new predefined time, a time that is longer than the particular predefined time based on the new set of environmental factors indicating that the new environment is more trusted than the particular environment.

10. A method as in claim 7 wherein choosing the new predefined time includes:

selecting, as the new predefined time, a time that is shorter than the particular predefined time based on the new set of environmental factors indicating that the new environment is less trusted than the particular environment.

11. A method as in claim 7 wherein sensing the new set of environmental factors from the new environment of the mobile device includes:

detecting that the mobile device is within a predefined range of a previously recognized external element.

12. A method as in claim 11 wherein detecting that the mobile device is within range of the previously recognized external element includes:

detecting, via a wireless interface of the mobile device, that the mobile device is in range of an authorized wireless network.

13. A method as in claim 11 wherein detecting that the mobile device is within range of the previously recognized external element includes:

detecting, via global positioning system (GPS) circuitry of the mobile device, that the mobile device is in motion.

14. A method as in claim 11 wherein detecting that the mobile device is within range of the previously recognized external element includes:

detecting, via global positioning system (GPS) circuitry of the mobile device, that the mobile device is in a particular location.

15. A method as in claim 11 wherein detecting that the mobile device is within range of the previously recognized external element includes:

detecting, via radio frequency (RF) circuitry of the mobile device, that the mobile device is a predefined vicinity of an RF beacon.

16. A method as in claim 11 wherein detecting that the mobile device is within range of the previously recognized external element includes:

detecting, via a microphone of the mobile device, that the mobile device is in a vicinity of the familiar audio source.

17. A method as in claim 11 wherein selecting the new expiration time based on the new set of environmental factors includes:

choosing the new expiration time from an expiration time database stored in memory of the mobile device, the new expiration time being chosen based on (i) detected presence of the previously recognized external element within the new environment and (ii) a current time reading.

18. A method as in claim 11 wherein selecting the new expiration time based on the new set of environmental factors includes:

choosing the new expiration time from an expiration time database stored in memory of the mobile device, the new expiration time being chosen based on (i) detected presence of the previously recognized external element within the new environment and (ii) a current set of transparently sensed user authentication factors obtained from the user.

19. An electronic apparatus, comprising:

memory; and

control circuitry coupled to the memory, the memory storing instructions which, when carried out by the control circuitry, cause the control circuitry to:

sense a set of environmental factors from a particular environment of a mobile device when the mobile device unlocks a computerized resource in response to successful authentication of a user, at least in part by detecting, via a microphone of the mobile device, whether the mobile device is in a vicinity of a familiar audio source;

select an expiration time based on the set of environmental factors, at least in part by choosing a relatively longer particular predefined time as the selected expiration time in response to the set of environmental factors indicating that the particular environment is a trusted environment and choosing a relatively shorter particular predefined time as the selected expiration time in response to the set of environmental factors indicating that the particular environment is not a trusted environment, and wherein the set of environmental factors indicate that the particular environment is a trusted environment when the mobile device is in a vicinity of the familiar audio source; and

configure an inactivity timer to re-lock access to the computerized resource of the mobile device when the inactivity timer identifies a time period of mobile device inactivity that reaches the selected expiration time.

20. A computer program product having a non-transitory computer readable medium which stores a set of instructions to control access to a computerized resource of a mobile device; the set of instructions, when carried out by computerized circuitry, causing the computerized circuitry to perform a method of:

sensing a set of environmental factors from a particular environment of a mobile device when the mobile device unlocks a computerized resource in response to successful authentication of a user, wherein sensing the set of environmental factors includes detecting, via a microphone of the mobile device, whether the mobile device is in a vicinity of a familiar audio source;

selecting an expiration time based on the set of environmental factors, at least in part by choosing a relatively longer particular predefined time as the selected expiration time in response to the set of environmental factors indicating that the particular environment is a trusted environment and choosing a relatively shorter particular predefined time as the selected expiration time in response to the set of environmental factors indicating that the particular environment is not a trusted environment, and wherein the set of environmental factors indicate that the particular environment is a trusted environment when the mobile device is in a vicinity of the familiar audio source; and

configuring an inactivity timer to re-lock access to the computerized resource of the mobile device when the inactivity timer identifies a time period of mobile device inactivity that reaches the selected expiration time.