Accessory Device Authentication

• US 20130232571A1
• Filed: 05/14/2012
• Published: 09/05/2013
• Est. Priority Date: 03/02/2012
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Edward C. Giaimo III
• Inventors: Belesiu, Jim Tom, Marshall, James Charles, Young, Robert D., Sherman, Nathan C., Giaimo, Edward C. III, Obie, Gene Robert, Neff, David, Sousa, Jose R.
• Granted Patent: US 8,935,774 B2
• Time in Patent Office: Days
• US Class Current: 726/21
• CPC Class Codes: G06F 1/26 Power supply means, e.g. regulation thereof for memories G11C
• CPC Class Codes: G06F 1/263 Arrangements for using multiple switchable power supplies, e.g. battery and AC G06F1/30 takes precedence

Abstract

Accessory device authentication techniques are described. In one or more embodiments, connection of an accessory device to a host computing device is detected. Responsive to the detection, an authentication sequence may occur to verify an identity and/or capabilities of the accessory device. Upon successful authentication of the accessory device, the host device may authorize the accessory device for power exchange interactions with the host device. The host device may then draw supplemental power from a power source associated with the authorized accessory device, such as a battery or power adapter. The host device may also enable the accessory device to obtain and use power supplied by the host device in some scenarios. Power exchange between a host device and an authorized accessory may be managed in accordance with capabilities of the accessory device that are identified during authentication.

Claims

1. A method implemented by a host computing device comprising:

detecting connection of an accessory device to the host computing device;

authenticating the accessory device to determine authorization of the accessory device for power exchange with the host computing device; and

upon successful authentication of the accessory device, authorizing power exchange with the accessory device.

2. A method as described in claim 1, further comprising obtaining supplemental power from the authorized accessory device when power exchange with the accessory device is authorized.

3. A method as described in claim 1, further comprising supplying supplemental power to the authorized accessory device when power exchange with the accessory device is authorized.

4. A method as described in claim 1, further comprising managing power jointly for the host computing device and the accessory device when power exchange with the accessory device is authorized.

5. A method as described in claim 1, further comprising:

when authentication of the accessory device is not successful, restricting power exchange with the accessory device.

6. A method as described in claim 1, wherein the detecting, authenticating, and authorizing are performed via one or more microcontrollers of the host computing device.

7. A method as described in claim 6, further comprising:

when the host computing device does not have sufficient power to operate the one or more microcontrollers, obtaining a restricted amount of power from the accessory device sufficient to operate the one or more microcontrollers to authenticate the accessory device for subsequent power exchange.

8. A method as described in claim 1, wherein the authenticating comprises:

requesting credentials from the accessory device via a communication channel established via the connection;

obtaining the credentials supplied by the accessory device; and

verifying the credentials by checking the credentials against known credentials for authorized devices.

9. A method implemented by a host computing device comprising:

exchanging a restricted amount of power between the host computing device and an accessory device that is not currently authenticated for power exchange with the host computing device, the restricted amount of power sufficient to perform authentication of the accessory device;

authenticating the accessory device for power exchange with the host computing device based on credentials supplied by the accessory device; and

upon successful authentication of the accessory device,

determining that supplemental power is available from the accessory device; and

obtaining the supplemental power from the accessory device for operation of the host computing device.

10. A method as described in claim 9, wherein the exchanging and authenticating are performed by one or more microcontrollers of the host computing device that operate independently of a primary processing system of the host computing device.

11. A method as described in claim 9, wherein the authenticating comprises:

obtaining the credentials from the accessory device, the credentials encoded using a designated hash algorithm;

decoding the credentials using the designated hash algorithm; and

comparing the credentials against a list of know credentials for authorized devices.

12. A method as described in claim 9, further comprising:

preventing subsequent power exchange with the accessory device when the authentication is unsuccessful.

13. A method as described in claim 9, further comprising:

upon successful authentication of the accessory device, managing power jointly for the host computing device and the accessory device.

14. A method as described in claim 13, wherein managing comprises selectively switching between multiple power sources available to the host computing device including at least power supplied via a power adapter, an internal battery of the host computing device, and an accessory battery of the accessory device.

15. A method as described in claim 9, wherein the exchanging and authenticating are performed responsive to connection of the accessory device to the host computing device via an interface, the interface creating a physical and communicative coupling of the accessory device to the host computing.

16. A method as described in claim 9, further comprising:

upon successful authentication of the accessory device,

determining that the accessory device lacks sufficient power to operate; and

supplying power from the host computing device for operation of the accessory device.

17. A host computing device comprising:

an interface configured to enable connection of one or more accessory devices to the host computing device at different times;

one or more microcontrollers configured to implement;

a power controller and an authentication module,

the authentication module operable to authenticate the one or more accessory devices responsive to connection of the accessory devices to the interface and expose results of the authentication to the power controller for subsequent power management decisions,

the power controller operable to control power exchange between the host device and the one or more accessory devices based at least in part upon the results of the authentication including;

authorizing power exchange with devices of the one or more accessory devices for which authentication is successful; and

restricting power exchange with devices of the one or more accessory devices for which authentication is not successful.

18. A host computing device as described in claim 18, wherein the power controller is further operable to allow limited exchange of power between the host computing device and the one or more accessory devices prior to authentication of the one or more accessory devices to enable operation of the one or more microcontrollers to perform the authentication.

19. A host computing device as described in claim 18, wherein the interface is configured to create a physical coupling and a communicative coupling of a particular accessory device when attached to the host computing device, the communicative coupling creating a communication channel between the one or more microcontrollers of the host computing device and a microcontroller of the particular accessory device through which credentials of the particular accessory device are conveyed to enable the authentication module to authenticate the particular accessory device.

20. A host computing device as described in claim 18, wherein the power controller and authentication module are implemented via two different microcontrollers of the host computing device.