Using an audio interface device to authenticate another device

1. A system, comprising:

at least one computing device; and

an authentication service executable in the at least one computing device, wherein when executed the authentication service causes the at least one computing device to at least:

receive an authentication request from a client device lacking both a touchscreen and a keyboard;

randomly generate an authentication code based at least in part on a required level of entropy and a time window for validity;

send the authentication code to the client device;

receive the authentication code from an audio interface device, the audio interface device having received the authentication code as speech recorded via a microphone of the audio interface device;

determine that the authentication code received from the audio interface device matches the authentication code sent to the client device;

determine that the authentication code was received from the audio interface device within the time window for validity;

determine an account for which the audio interface device is authenticated;

authenticate the client device for access to the account;

in response to authenticating the client device, receive additional speech from the audio interface device recorded via the microphone, the additional speech including a specification of account data that is authorized to be shared with a third party associated with the client device; and

implement an action in response to the additional speech.

2. The system of claim 1 , wherein when executed the authentication service further causes the at least one computing device to at least:

determine that a risk-based factor does not preclude authentication of the client device for access to the account; and

issue a registration token to the client device for access to the account.

3. The system of claim 1 , wherein when executed the authentication service further causes the at least one computing device to at least:

determine a plurality of users associated with a location of the audio interface device;

determine that the speech matches a voice profile of one of the plurality of users; and

identify the account from a plurality of accounts based at least in part on the speech matching the voice profile of the one of the plurality of users.

4. The system of claim 1 , wherein the audio interface device lacks a display.

5. A system, comprising:

at least one computing device; and

an authentication service executable in the at least one computing device, wherein when executed the authentication service causes the at least one computing device to at least:

cause a first client device to present an authentication code via an output device of the first client device;

receive the authentication code from a second client device, wherein the second client device is in an authenticated state for access to an account, and the second client device received the authentication code from an environmental sensor while in a listening mode;

authenticate the first client device for access to the account in response to determining that the authentication code received from the second client device matches the authentication code presented by the first client device;

in response to authenticating the first client device, receive an additional input from the second client device recorded via the environmental sensor, the additional input including a specification of account data that is authorized to be shared with a third party associated with the first client device; and

implement an action in response to the additional speech.

6. The system of claim 5 , wherein when executed the authentication service further causes the at least one computing device to at least:

randomly generate the authentication code based at least in part on a required level of entropy and a time window for validity; and

send the authentication code to the first client device via a network.

7. The system of claim 5 , wherein the first client device is authenticated further in response to:

performing voice identification on speech including the authentication code received by the second client device; and

determining that an identified voice matches a voice profile of a user associated with the account.

8. The system of claim 5 , wherein the first client device is authenticated further in response to determining that the authentication code is valid for the account according to a time window for validity for the authentication code.

9. The system of claim 5 , wherein the second client device enters the listening mode after detecting a wake signal via the second client device.

10. The system of claim 5 , wherein the second client device enters the listening mode after detecting a button press via the second client device.

11. The system of claim 5 , wherein the output device of the first client device is a local network interface, and the first client device presents the authentication code by sending broadcast data via the local network interface.

12. The system of claim 5 , wherein the output device of the first client device is a display, and the first client device presents the authentication code by showing the authentication code on the display.

13. The system of claim 5 , wherein the output device of the first client device is a speaker, and the first client device presents the authentication code by emitting an audio signal via the speaker.

14. The system of claim 13 , wherein the audio signal encodes the authentication code in an ultrasonic frequency range.

15. The system of claim 13 , wherein the audio signal encodes the authentication code as a voice generated by a voice synthesizer.

16. A method, comprising:

causing, via at least one of one or more computing devices, a first client device to present an authentication code via a display of the first client device;

receiving, via at least one of the one or more computing devices, the authentication code from a second client device, wherein the second client device is in an authenticated state for access to an account, and the second client device received the authentication code as speech recorded via a microphone;

authenticating, via at least one of the one or more computing devices, the first client device for access to the account in response to determining that the authentication code received from the second client device matches the authentication code presented by the first client device;

in response to authenticating the first client device, receiving, via at least one of the one or more computing devices, additional speech from the second client device recorded via the microphone, the additional speech including a specification of account data that is authorized to be shared with a third party associated with the first client device; and

implementing, via at least one of the one or more computing devices, an action in response to the additional speech.

17. The method of claim 16 , further comprising:

randomly generating, via at least one of the one or more computing devices, the authentication code; and

sending, via at least one of the one or more computing devices, the authentication code to the first client device via a network.

18. The method of claim 16 , wherein the account is unspecified by the first client device.

19. The method of claim 16 , further comprising authorizing, via at least one of the one or more computing devices, a transaction associated with the first client device in response to determining that the authentication code received from the second client device matches the authentication code presented by the first client device.

20. The method of claim 16 , wherein the second client device enters a listening mode after detecting a wake word via the microphone.