Code signing system and method

• US 20040025022A1
• Filed: 03/20/2003
• Published: 02/05/2004
• Est. Priority Date: 09/21/2000
• Status: Active Grant

• Current Assignee: Blackberry Limited
• Original Assignee: Blackberry Limited
• Inventors: Brown, Michael S, Little, Herbert A, Yach, David P
• Granted Patent: US 8,489,868 B2
• Time in Patent Office: Days
• US Class Current: 713/176
• CPC Class Codes: G06F 21/10 Protecting distributed programs or content, e.g. vending or licensing of copyrighted material protection in video systems or pay television H04N7/16 ; Digital rights management [DRM]
• CPC Class Codes: G06F 21/121 Restricting unauthorised execution of programs
• CPC Class Codes: G06F 21/51 at application loading time, e.g. accepting, rejecting, starting or inhibiting executable software based on integrity or source reliability
• CPC Class Codes: G06F 21/629 to features or functions of an application
• CPC Class Codes: H04L 63/067 using one-time keys cryptographic mechanisms or cryptographic arrangements for generation of one-time passwords H04L9/0863
• CPC Class Codes: H04L 63/0823 using certificates cryptographic mechanisms or cryptographic arrangements for entity authentication involving certificates H04L9/3263
• CPC Class Codes: H04L 63/123 received data contents, e.g. message integrity
• CPC Class Codes: H04L 63/126 the source of the received data
• CPC Class Codes: H04L 63/1483 service impersonation, e.g. phishing, pharming or web spoofing detection of rogue wireless access points H04W12/12
• CPC Class Codes: H04L 9/321 involving a third party or a trusted authority
• CPC Class Codes: H04L 9/3236 using cryptographic hash functions
• CPC Class Codes: H04L 9/3247 involving digital signatures
• CPC Class Codes: H04W 4/60 Subscription-based services using application servers or record carriers, e.g. SIM application toolkits

Abstract

A code signing system and method is provided. The code signing system operates in conjunction with a signed software application having a digital signature and includes an application platform, an application programming interface (API), and a virtual machine. The API is configured to link the software application with the application platform. The virtual machine verifies the authenticity of the digital signature in order to control access to the API by the software application.

Claims

1. A code signing system for operation in conjunction with a software application having a digital signature, comprising:

an application platform;

an application programming interface (API) configured to link the software application with the application platform; and

a virtual machine that verifies the authenticity of the digital signature in order to control access to the API by the software application.

2. The code signing system of claim 1, wherein the virtual machine denies the software application access to the API if the digital signature is not authentic.

3. The code signing system of claim 1, wherein the virtual machine purges the software application if the digital signature is not authentic.

4. The code signing system of claim 1, wherein the code signing system is installed on a mobile device.

5. The code signing system of claim 1, wherein the digital signature is generated by a code signing authority.

14. The code signing system of claim 1, further comprising:

a plurality of API libraries each including a plurality of APIs, wherein the virtual machine controls access to the plurality of API libraries by the software application.

15. The code signing system of claim 14, wherein one or more of the plurality of API libraries is classified as sensitive, and wherein the virtual machine uses the digital signature to control access to the sensitive API libraries by the software application.

16. The code signing system of claim 15, wherein the software application includes a unique digital signature for each sensitive API library.

17. The code signing system of claim 16, wherein:

the software application includes a signature identification for each unique digital signature;

each sensitive API library includes a signature identifier; and

the virtual machine compares the signature identification and the signature identifier to match the unique digital signatures with sensitive API libraries.

18. The code signing system of claim 1, wherein the digital signature is generated using a private signature key, and the virtual machine uses a public signature key to verify the authenticity of the digital signature.

19. The code signing system of claim 18, wherein:

the digital signature is generated by applying the private signature key to a hash of the software application; and

the virtual machine verifies the authenticity of the digital signature by generating a hash of the software application to obtain a generated hash, applying the public signature key to the digital signature to obtain a recovered hash, and comparing the generated hash with the recovered hash.

20. The code signing system of claim 1, wherein the API further comprises:

a description string that is displayed by the mobile device when the software application attempts to access the API.

21. The code signing system of claim 1, wherein the application platform comprises an operating system.

22. The code signing system of claim 1, wherein the application platform comprises one or more core functions of a mobile device.

23. The code signing system of claim 1, wherein the application platform comprises hardware on a mobile device.

24. The code signing system of claim 23, wherein the hardware comprises a subscriber identity module (SIM) card.

25. The code signing system of claim 1, wherein the software application is a Java application for a mobile device.

26. The code signing system of claim 1, wherein the API interfaces with a cryptographic routine on the application platform.

27. The code signing system of claim 1, wherein the API interfaces with a proprietary data model on the application platform.

28. The code signing system of claim 1, wherein the virtual machine is a Java virtual machine installed on a mobile device.

6. A code signing system for operation in conjunction with a software application having a digital signature, comprising:

an application platform;

a plurality of application programming interfaces (APIs), each configured to link the software application with a resource on the application platform; and

a virtual machine that verifies the authenticity of the digital signature in order to control access to the API by the software application,

wherein the virtual machine verifies the authenticity of the digital signature in order to control access to the plurality of APIs by the software application.

7. The code signing system of claim 6, wherein the plurality of APIs are included in an API library.

8. The code signing system of claim 6, wherein one or more of the plurality of APIs is classified as sensitive, and wherein the virtual machine uses the digital signature to control access to the sensitive APIs.

9. The code signing system of claim 8, for operation in conjunction with a plurality of software applications, wherein one or more of the plurality of software applications has a digital signature, and wherein the virtual machine verifies the authenticity of the digital signature of each of the one or more of the plurality of software applications in order to control access to the sensitive APIs by each of the plurality of software applications.

10. The code signing system of claim 6, wherein the resource on the application platform comprises a wireless communication system.

11. The code signing system of claim 6, wherein the resource on the application platform comprises a cryptographic module which implements cryptographic algorithms.

12. The code signing system of claim 6, wherein the resource on the application platform comprises a data store.

13. The code signing system of claim 6, wherein the resource on the application platform comprises a user interface (UI).

29. A method of controlling access to sensitive application programming interfaces on a mobile device, comprising the steps of:

loading a software application on the mobile device that requires access to a sensitive application programming interface (API);

determining whether or not the software application includes a digital signature associated with the sensitive API; and

if the software application does not include a digital signature associated with the sensitive API, then denying the software application access to the sensitive API.

30. The method of claim 29, comprising the additional step of:

if the software application does not include a digital signature associated with the sensitive API, then purging the software application from the mobile device.

31. The method of claim 29, wherein the digital signature is generated by a code signing authority.

32. The method of claim 29, comprising the additional steps of:

if the software application includes a digital signature associated with the sensitive API, then verifying the authenticity of the digital signature; and

if the digital signature is not authentic, then denying the software application access to the sensitive API.

33. The method of claim 32, comprising the additional step of:

if the digital signature is not authentic, then purging the software application from the mobile device.

34. The method of claim 32, wherein the digital signature is generated by applying a private signature key to a hash of the software application, and wherein the step of verifying the authenticity of the digital signature is performed by a method comprising the steps of:

storing a public signature key that corresponds to the private signature key on the mobile device;

generating a hash of the software application to obtain a generated hash;

applying the public signature key to the digital signature to obtain a recovered hash; and

comparing the generated hash with the recovered hash.

35. The method of claim 34, wherein the digital signature is generated by calculating a hash of the software application and applying the private signature key.

36. The method of claim 29, comprising the additional step of:

displaying a description string that notifies a user of the mobile device that the software application requires access to the sensitive API.

37. The method of claim 36, comprising the additional step of:

receiving a command from the user granting or denying the software application access to the sensitive API.

38. A method of controlling access to an application programming interface (API) on a mobile device by a software application created by a software developer, comprising the steps of:

receiving the software application from the software developer;

reviewing the software application to determine if it may access the API;

if the software application may access the API, then appending a digital signature to the software application;

verifying the authenticity of a digital signature appended to a software application; and

providing access to the API to software applications for which the appended digital signature is authentic.

39. The method of claim 38, wherein the step of reviewing the software application is performed by a code signing authority.

40. The method of claim 38, wherein the step of appending the digital signature to the software application is performed by a method comprising the steps of:

calculating a hash of the software application; and

applying a signature key to the hash of the software application to generate the digital signature.

41. The method of claim 40, wherein the hash of the software application is calculated using the Secure Hash Algorithm (SHA1).

42. The method of claim 40, wherein the step of verifying the authenticity of a digital signature comprises the steps of:

providing a corresponding signature key on the mobile device;

calculating the hash of the software application on the mobile device to obtain a calculated hash;

applying the corresponding signature key to the digital signature to obtain a recovered hash; and

determining if the digital signature is authentic by comparing the calculated hash with the recovered hash.

43. The method of claim 42, comprising the further step of, if the digital signature is not authentic, then denying the software application access to the API.

44. The method of claim 42, wherein the signature key is a private signature key and the corresponding signature key is a public signature key.

45. A method of controlling access to a sensitive application programming interface (API) on a mobile device, comprising the steps of:

registering one or more software developers that are trusted to design software applications which access the sensitive API;

receiving a hash of a software application;

determining if the software application was designed by one of the registered software developers; and

if the software application was designed by one of the registered software developers, then generating a digital signature using the hash of the software application, wherein

the digital signature may be appended to the software application; and

the mobile device verifies the authenticity of the digital signature in order to control access to the sensitive API by the software application.

46. The method of claim 45, wherein the step of generating the digital signature is performed by a code signing authority.

47. The method of claim 45, wherein the step of generating the digital signature is performed by applying a signature key to the hash of the software application.

48. The method of claim 47, wherein the mobile device verifies the authenticity of the digital signature by performing the additional steps of:

providing a corresponding signature key on the mobile device;

calculating the hash of the software application on the mobile device to obtain a calculated hash;

applying the corresponding signature key to the digital signature to obtain a recovered hash;

determining if the digital signature is authentic by comparing the calculated hash with the recovered hash; and

if the digital signature is not authentic, then denying the software application access to the sensitive API.

49. A method of restricting access to application programming interfaces on a mobile device, comprising the steps of:

loading a software application on the mobile device that requires access to one or more application programming interface (API);

determining whether or not the software application includes an authentic digital signature associated with the mobile device; and

if the software application does not include an authentic digital signature associated with the mobile device, then denying the software application access to the one or more APIs.

50. The method of claim 49, comprising the additional step of:

if the software application does not include an authentic digital signature associated with the mobile device, then purging the software application from the mobile device.

51. The method of claim 49, wherein:

the software application includes a plurality of digital signatures; and

the plurality of digital signatures includes digital signatures respectively associated with different types of mobile devices.

52. The method of claim 51, wherein each of the plurality of digital signatures is generated by a respective corresponding code signing authority.

53. The method of claim 49, wherein the step of determining whether or not the software application includes an authentic digital signature associated with the mobile device comprises the additional steps of:

determining if the software application includes a digital signature associated with the mobile device; and

if so, then verifying the authenticity of the digital signature.

54. The method of claim 53, wherein the one or more APIs includes one or more APIs classified as sensitive, and the method further comprises the steps of, for each sensitive API:

determining whether or not the software application includes an authentic digital signature associated with the sensitive API; and

if the software application does not include an authentic digital signature associated with the sensitive API, then denying the software application access to the sensitive API.

55. The method of claim 52, wherein each of the plurality of digital signatures is generated by its corresponding code signing authority by applying a respective private signature key associated with the code signing authority to a hash of the software application.

56. The method of claim 55, wherein the step of determining whether or not the software application includes an authentic digital signature associated with the mobile device comprises the steps of:

determining if the software application includes a digital signature associated with the mobile device; and

if so, then verifying the authenticity of the digital signature, wherein the step of verifying the authenticity of the digital signature is performed by a method comprising the steps of;

storing a public signature key on a mobile device that corresponds to the private signature key associated with the code signing authority which generates the signature associated with the mobile device;

generating a hash of the software application to obtain a generated hash;

applying the public signature key to the digital signature to obtain a recovered hash; and

comparing the generated hash with the recovered hash.