Secure bootstrapping of client device with trusted server provided by untrusted cloud service

1. A method comprising:

at a provisioning client, obtaining an identifier from a public server;

obtaining a one-time password from a trusted server;

combining the one-time password with the identifier to create an activation code for a client device; and

presenting the activation code to the client device, enabling the client device to download trusted cryptographic information from the trusted server in a communication session that is secured using the one-time password.

2. The method of claim 1 , wherein obtaining the identifier comprises:

sending a request for the identifier, wherein the request for the identifier includes an address of the trusted server; and

receiving the identifier from the public server.

3. The method of claim 1 , wherein obtaining the one-time password comprises:

sending a request for the one-time password to the trusted server; and

receiving the one-time password from the trusted server through a previously secured communication session between the trusted server and the provisioning client.

4. The method of claim 3 , wherein the request for the one-time password includes the identifier obtained from the public server.

5. The method of claim 1 , wherein presenting the activation code to the client device comprises displaying the activation code to a user for entry in the client device.

6. The method of claim 1 , wherein the communication session is secured according to a Password Authenticated Key Exchange (PAKE) protocol using the one-time password as a shared secret in the PAKE protocol.

7. The method of claim 6 , wherein the PAKE protocol securing the communication session between the trusted server and the client device is proxied via the public server.

8. An apparatus comprising:

a communication interface that enables network communications; and

a processor, coupled to the communication interface, and configured to:

at a provisioning client, obtain an identifier from a public server via the communication interface;

obtain a one-time password from a trusted server via the communication interface;

combine the one-time password with the identifier to create an activation code for a client device; and

present the activation code to the client device, enabling the client device to download trusted cryptographic information from the trusted server in a communication session that is secured using the one-time password.

9. The apparatus of claim 8 , wherein the processor is configured to obtain the identifier by:

causing the communication interface to send a request for the identifier, wherein the request for the identifier includes an address of the trusted server; and

receiving the identifier from the public server via the communication interface.

10. The apparatus of claim 8 , wherein the processor is configured to obtain the one-time password by:

causing the communication interface to send a request for the one-time password to the trusted server; and

receiving the one-time password via the communication interface from the trusted server through a previously secured communication session between the trusted server and the provisioning client.

11. The apparatus of claim 10 , wherein the processor is configured to include the identifier obtained from the public server in the request for the one-time password.

12. The apparatus of claim 8 , further comprising a display, wherein the processor is configured to present the activation code to the client device by causing the display to show the activation code to a user for entry in the client device.

13. The apparatus of claim 8 , wherein the communication session is secured according to a Password Authenticated Key Exchange (PAKE) protocol using the one-time password as a shared secret in the PAKE protocol.

14. The apparatus of claim 13 , wherein the PAKE protocol securing the communication session between the trusted server and the client device is proxied via the public server.

15. A system comprising:

a client device;

a trusted server configured to generate a one-time password for the client device; and

a provisioning client configured to:

obtain an identifier from a public server;

obtain the one-time password from the trusted server;

combine the one-time password with the identifier to create an activation code for the client device; and

present the activation code to the client device, enabling the client device to download trusted cryptographic information from the trusted server in a communication session that is secured using the one-time password.

16. The system of claim 15 , wherein the provisioning client is configured to obtain the identifier by:

sending a request for the identifier, wherein the request for the identifier includes an address of the trusted server; and

receiving the identifier from the public server.

17. The system of claim 15 , wherein the provisioning client is configured to obtain the one-time password by:

sending a request for the one-time password to the trusted server; and

receiving the one-time password from the trusted server through a previously secured communication session between the trusted server and the provisioning client.

18. The system of claim 17 , wherein the provisioning client is configured to include the identifier obtained from the public server in the request for the one-time password.

19. The system of claim 15 , wherein the provisioning client is configured to present the activation code to the client device by displaying the activation code to a user for entry in the client device.

20. The system of claim 15 , wherein the communication session is secured according to a Password Authenticated Key Exchange (PAKE) protocol using the one-time password as a shared secret in the PAKE protocol.