SUBSIDY LOCK ENABLED HANDSET DEVICE WITH ASYMMETRIC VERIFICATION UNLOCKING CONTROL AND METHOD THEREOF

• US 20080005577A1
• Filed: 06/30/2006
• Published: 01/03/2008
• Est. Priority Date: 06/30/2006
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Rager, Kent D., Voss, Joel D., Debates, Scott P.
• Granted Patent: US 7,886,355 B2
• Time in Patent Office: Days
• US Class Current: 713/183
• CPC Class Codes: G06F 21/575 Secure boot
• CPC Class Codes: H04L 2209/60 Digital content management, e.g. content distribution
• CPC Class Codes: H04L 2209/80 Wireless network architectures or network communication protocols for wireless network security H04W12/00
• CPC Class Codes: H04L 9/3247 involving digital signatures
• CPC Class Codes: H04L 9/3265 using certificate chains, trees or paths; Hierarchical trust model
• CPC Class Codes: H04W 12/106 Packet or message integrity
• CPC Class Codes: H04W 12/128 Anti-malware arrangements, e.g. protection against SMS fraud or mobile malware
• CPC Class Codes: H04W 12/48 using secure binding, e.g. securely binding identity modules to devices, services or applications

Abstract

A method for controlling subsidy locking of a handset device includes storing, in a handset device, an asymmetrically digitally signed subsidy unlock data block that has been modified based on a password after signing (505); modifying the stored unlock data block based on a received subsidy unlock password (510); and granting subsidy unlock status if the asymmetric digital signature of the modified, stored unlock data block properly verifies (510). A method (110) for controlling subsidy locking of a handset device includes storing, in the handset device, an asymmetrically digitally signed subsidy unlock data block that comprises a password portion that has been modified after signing (112); replacing the contents of the modified password portion with a received subsidy unlock password to produce an updated subsidy unlock data block (116); and granting subsidy unlock status if the asymmetric digital signature of the updated subsidy unlock data block properly verifies (118).

Claims

1. A method for controlling subsidy locking of a handset device comprising:

storing, in the handset device, an asymmetrically digitally signed subsidy unlock data block that comprises a password portion that is modified after the subsidy unlock data block is digitally signed;

replacing the contents of the modified password portion with a received subsidy unlock password to produce an updated subsidy unlock data block for verification; and

granting subsidy unlock status if the updated subsidy unlock data block properly verifies based on an asymmetric digital signature verification process.

2. The method of claim 1 wherein a hash digest of the received subsidy unlock password replaces the contents of the modified password portion.

3. The method of claim 1 wherein granting subsidy unlock status comprises overwriting an active data block on the handset device with the subsidy unlock data block.

4. The method of claim 1 wherein the subsidy unlock data block further comprises a locking state parameter and wherein granting unlock status further requires verification of that the locking state parameter is set to the unlock state.

5. The method of claim 1 wherein the subsidy unlock data block further comprises a binding parameter associated with a circuit in the handset device and wherein granting subsidy unlock status further requires that the binding parameter matches the circuit in the handset device.

6. A method for controlling subsidy locking of a handset device comprising:

verifying, during power-up, SIM insertion, or a periodic interval of a handset device, an asymmetrical digital signature of an active data block stored in the handset device using a public key stored in the handset device;

modifying an asymmetrically digitally signed subsidy unlock data block stored in the handset device by writing a subsidy unlock password in a password portion of the subsidy unlock data block wherein the subsidy unlock data block further comprises a locking state parameter;

thereafter, verifying the asymmetric digital signature of the subsidy unlock data block using the public key; and

overwriting the active data block with the subsidy unlock data block to thereby subsidy unlock the handset device if the asymmetric digital signature of the subsidy unlock data block verifies and if the locking state parameter is set to the unlock state.

7. The method of claim 6 wherein a hash digest of the subsidy unlock password is written into the password portion.

8. The method of claim 6 wherein verifying the asymmetric digital signature of the subsidy unlock data block further comprises verifying a certificate chain attached to the subsidy unlock data block.

9. The method of claim 6 wherein the subsidy unlock data block further comprises a binding parameter associated with a circuit in the handset device and wherein overwriting the active data block with the subsidy unlock data block further requires that the binding parameter matches the circuit in the handset device.

10. The method of claim 6 further comprising granting test SIM or emergency call only status if the asymmetrical digital signature of the active data block does not verify during power-up, SIM insertion, or a periodic interval of the handset device.

11. The method of claim 6 wherein the active data block further comprises a locking state parameter and further comprising granting subsidy unlock status if the asymmetric digital signature of the active data block verifies during power-up, SIM insertion, or a periodic interval of the handset device and if the active data block locking state parameter is set to the unlock state.

12. The method of claim 6 further comprising:

modifying an asymmetric digitally signed partial unlock data block stored in the handset device by writing the subsidy unlock password in a password portion of the partial unlock data block if the asymmetric digital signature of the subsidy unlock data block does not verify wherein the partial unlock data block further comprises a locking state parameter;

thereafter, verifying the asymmetric digital signature of the partial unlock data block using the public key; and

overwriting the active data block stored in the handset device with the partial unlock data block to thereby partially subsidy unlock the handset device if the asymmetric digital signature of the partial unlock data block verifies and if the partial unlock data block locking state parameter is set to a partial unlock state.

13. The method of claim 12 wherein partially subsidy unlocking leaves the handset device locked to a list of operator networks.

14. A subsidy-locked handset device comprising:

memory storing an asymmetrically digitally signed subsidy unlock data block comprising a password portion that is modified after the subsidy unlock data block is digitally signed; and

a controller operatively coupled to the memory and operative to replace the contents of the password portion with a received subsidy unlock password to produce an updated subsidy unlock data block for verification and to grant subsidy unlock status if the updated subsidy unlock data block properly verifies based on an asymmetric digital signature verification process.

15. The device of claim 14 further comprising a SIM card operatively coupled to the controller.

16. The device of claim 14 further comprising an asymmetric signature verification module operative to verify the asymmetric digital signature of the subsidy unlock data block based on an asymmetric digital signature verification process.

17. The device of claim 14 further comprising a user interface operative to provide user entry of the subsidy unlock password into the handset device.

18. The device of claim 14 wherein the controller is operative to generate a hash digest of the subsidy unlock password and to write the hash digest into the modified password portion.

19. The device of claim 14 wherein the subsidy unlock data block further comprises a locking state parameter and wherein the controller is further operative to grant subsidy unlock status if the locking state parameter is set to the unlock state.

20. The device of claim 14 wherein the subsidy unlock data block further comprises a binding parameter associated with a circuit in the handset device and wherein the controller is further operative to grant subsidy unlock status if the binding parameter matches the circuit in the handset device.

21. The device of claim 14 wherein the memory further comprises an asymmetrically digitally signed, partial unlock data block comprising a second password portion and a locking state parameter wherein the second password portion is modified after the partial unlock data block is digitally signed and wherein the controller is further operative to replace the contents of the second password portion with the received subsidy unlock password to produce an updated partial unlock data block for verification, and to grant partial unlock status if the updated partial unlock data block properly verifies based on an asymmetric digital signature verification process and if the locking state parameter is set to a partial unlock state.

22. A storage medium comprising executable instructions that when read by one or more processing units, causes the one or more processing units to:

store, in the handset device, an asymmetrically digitally signed subsidy unlock data block comprising a password portion that is modified after the subsidy unlock data block is digitally signed;

replace the contents of the password portion with a received subsidy unlock password to produce an updated subsidy unlock data block for verification; and

grant subsidy unlock status if the updated subsidy unlock data block properly verifies based on an asymmetric digital signature verification process.

23. The storage medium of claim 22 containing executable instructions that when read by one or more processing units, causes the one or more processing units to replace the contents of the password portion with a hash digest of the received subsidy unlock password.

24. The storage medium of claim 22 containing executable instructions that when read by one or more processing units, causes the one or more processing units to overwrite an active data block in the handset device with the subsidy unlock data block when subsidy unlock status is granted.

25. The storage medium of claim 22 containing executable instructions that when read by one or more processing units, causes the one or more processing units to verify that the subsidy unlock data block comprises a locking state parameter set to the unlock state prior to granting subsidy unlock status.

26. The storage medium of claim 22 containing executable instructions that when read by one or more processing units, causes the one or more processing units to verify that subsidy unlock data block comprises a binding parameter associated with a circuit in the handset device prior to granting subsidy unlock status.

27. A method for controlling subsidy-locking a handset device comprising:

generating a subsidy unlock data block comprising a password portion, a locking state parameter, and a binding parameter associated with a circuit in a handset device;

asymmetrically digitally signing the subsidy unlock data block;

modifying the password portion of the asymmetrically digitally signed subsidy unlock data block; and

sending the modified asymmetrically digitally signed subsidy unlock data block to a handset device.

28. The method of claim 27 further comprising:

asymmetrically digitally signing an active data block comprising a locking state and a binding parameter associated with a circuit in a handset device; and

sending the asymmetrically digitally signed active data block to the handset device.

29. A subsidy-locking device comprising:

memory; and

a controller operatively coupled to the memory and to a handset device and operative to store in memory a subsidy unlock data block comprising a password portion, a locking state parameter, and a binding parameter associated with a circuit in a handset device, to asymmetrically digitally sign the subsidy unlock data block, to modify the password portion of the asymmetrically digitally signed subsidy unlock data block, and to send the modified asymmetrically digitally signed subsidy unlock data block to the handset device.

30. The subsidy locking device of claim 29 wherein the controller is further operative to store in memory an active data block comprising a locking state parameter and a binding parameter associated with a circuit in a handset device, to asymmetrically digitally sign the active data block, and send the asymmetrically digitally signed subsidy active data block to the handset device.

31. A method for controlling subsidy locking of a handset device comprising:

storing, in a handset device, an asymmetrically digitally signed subsidy unlock data block that has been modified after signing wherein the modification is based on a password;

modifying the stored asymmetrically digitally signed subsidy unlock data block based on a received subsidy unlock password; and

granting subsidy unlock status if the modified, stored asymmetrically digitally signed subsidy unlock data block properly verifies based on an asymmetric digital signature verification process.

32. The method of claim 31 wherein the modifying based on a password includes encrypting the asymmetrically digitally signed subsidy unlock data block based on the password.

33. The method of claim 32 wherein the password is an encryption key for the encrypting.

34. The method of claim 32 wherein the password is an initialization vector for the encrypting.

35. The method of claim 32 wherein the password is used to derive an initialization vector for the encrypting.

36. The method of claim 32 wherein the encrypting is based on a hash digest of the password.

37. The method of claim 31 wherein modifying the stored asymmetrically digitally signed subsidy unlock data block based on a received subsidy unlock password includes decrypting the stored asymmetrically digitally signed subsidy unlock data block based on the received subsidy unlock password.

38. The method of claim 37 wherein the received subsidy unlock password is a decryption key for the decrypting.

39. The method of claim 37 wherein the received subsidy unlock password is an initialization vector for the decrypting.

40. The method of claim 37 wherein the received subsidy unlock password is used to derive an initialization vector for the decrypting.

41. The method of claim 37 wherein the decrypting is based on a hash digest of the password.

42. The method of claim 31 wherein the modifying based on a password includes altering the password held in a portion of the asymmetrically digitally signed subsidy unlock data block and wherein modifying the stored asymmetrically digitally signed subsidy unlock data block based on a received subsidy unlock password includes inserting the received subsidy unlock password into the stored asymmetrically digitally signed subsidy unlock data block.