PAIRING AN ACCESSORY WITH A HOST DEVICE USING ACCESSORY OUTPUT DEVICE

• US 20120231740A1
• Filed: 03/10/2011
• Published: 09/13/2012
• Est. Priority Date: 03/10/2011
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Bradley, Robert
• Granted Patent: US 8,521,086 B2
• Time in Patent Office: Days
• US Class Current: 455/41.3
• CPC Class Codes: G06F 21/445 by mutual authentication, e.g. between devices or programs
• CPC Class Codes: G06F 2221/2129 Authenticate client device independently of the user
• CPC Class Codes: H04L 63/061 for key exchange, e.g. in peer-to-peer networks cryptographic mechanisms or cryptographic arrangements for key agreement H04L9/0838
• CPC Class Codes: H04L 63/08 for authentication of entities cryptographic mechanisms or cryptographic arrangements for entity authentication H04L9/32
• CPC Class Codes: H04M 1/72412 using two-way short-range wireless interfaces

Abstract

A method for pairing an accessory with a host device includes placing an output device of the accessory into a randomly selected state N-times. The information about the current state of the accessory is provided to a host device after each state selection for N number of times. Thereafter, the host device generates an authentication code based on the N inputs and the accessory generates another authentication code based on the N selected states. The authentication codes can be then compared and can be used to “pair” the host device and the accessory, allowing secure communication.

Claims

1. A method for pairing with an accessory, the method comprising, by a host device:

instructing the accessory to select a state for an output device;

receiving an input indicative of the selected state of the output device;

repeating the instructing and the receiving until a number (N) of inputs have been received;

generating a passcode based at least in part on the N inputs; and

pairing with the accessory based on the passcode.

2. The method of claim 1 wherein receiving an input comprises, in one instance, receiving two successive inputs indicative of a same state of the output device.

3. The method of claim 1 wherein the output device is an illumination device.

4. The method of claim 3 wherein the state of the illumination device is selected from a group consisting of an ‘

on’

state and an ‘

off’

state.

5. The method of claim 1 wherein the output device is an audio device.

6. The method of claim 1 wherein generating the passcode comprises:

determining at least one identifier, wherein the at least one identifier is common to the host device and the accessory;

concatenating the at least one identifier and the N inputs to generate a concatenated input; and

encoding the concatenated input to generate the passcode.

7. A host device comprising:

a processor;

a memory coupled to the processor;

an accessory interface configured to communicate with an accessory; and

an input interface configured to receive input from a user;

wherein the processor is configured to;

send a message instructing the accessory to select a state for an output device;

receive a first input via the input interface, wherein the first input is indicative of the selected state of the output device;

repeat the send and the receive steps until a number (N) of inputs are received, wherein the N inputs together represent a random code;

encode the random code to generate a first authentication code; and

pair with the accessory using the first authentication code.

8. The host device of claim 7 wherein the processor is further configured to:

determine, prior to encoding the random code, an identifier common to the accessory and the host device;

combine the identifier and the random code to generate a concatenated input; and

encode the concatenated input to generate the first authentication code.

9. The host device of claim 7 wherein to pair with the accessory using the first authentication code, the processor is further configured to:

receive a second authentication code from the accessory;

compare the second authentication code to the first authentication code; and

allow the accessory access to the host device if the second authentication code matches the first authentication code.

10. An accessory comprising:

a processor;

an interface coupled with the processor and configured to communicate with a host device;

an output device coupled with the processor; and

a memory coupled with the processor and including program code for generating a passcode, wherein the processor in conjunction with the memory is configured to;

randomly select a state for the output device;

place the output device in the selected state;

receive instructions from the host device to select a next state for the output device;

select the next state and place the output device in the next state in response to the instructions from a host device;

repeat the randomly select, the place, the receive, and the select the next state steps for a predetermined number of times to generate a random code, the random code being a sequence indicative of selected states of the output device; and

generate an authentication code based at least in part on the random code.

11. The accessory of claim 10 wherein the processor is further configured to:

determine an identifier;

combine the identifier and the random code to generate a concatenated code;

encode the concatenated code to generate the authentication code; and

access the host device using the authentication code.

12. The accessory of claim 11 wherein in the event that the accessory and the host device fail to communicate using the authentication code, the processor generates a new random code.

13. The accessory of claim 10 wherein the output device comprises an optical indicator.

14. The accessory of claim 13 wherein a first state corresponds to the optical indicator being ON and a second state corresponds to the optical indicator being OFF.

15. The accessory of claim 10 wherein the output device comprises an audio device.

16. A non-transitory computer-readable storage medium including instructions which when executed by a processor in an accessory including an output device, cause the processor to perform a method of generating an authentication code, the method comprising:

receiving a count from a host device, the count indicating a number (N) of iterations of a code-generation operation to perform;

for each of the N iterations of the code-generating operation;

randomly selecting a state for the output device;

placing the output device in the selected state;

receiving instruction from the host to select a next state for the output device; and

in response to the instruction, randomly selecting the next state for the output device and placing the output device in the next state; and

subsequent to the N iterations of the code-generating operation, computing an authentication code based at least in part on the N randomly selected states.

17. The computer-readable storage medium of claim 16 wherein the output device comprises an illumination device capable of displaying a plurality of colors and wherein randomly selecting a state includes randomly selecting one of the colors.

18. The computer-readable storage medium of claim 16 wherein the output device comprises an audio unit and wherein randomly selecting a state includes selecting duration of a tone to be emitted by the audio unit.

19. The computer-readable storage medium of claim 16 wherein N is at least 2 and not greater and 64.

20. The computer-readable storage medium of claim 16 wherein computing an authentication code further comprises:

concatenating the N randomly selected state information with at least one identifier to generate a concatenated input; and

encoding the concatenated input to generate the authentication code.

21. The computer-readable storage medium of claim 20 wherein the at least one identifier is received from the host device.