Protecting cryptographic secrets using file system attributes

• US 9,171,145 B2
• Filed: 05/24/2013
• Issued: 10/27/2015
• Est. Priority Date: 05/24/2013
• Status: Active Grant

• Current Assignee: CA, Inc. (d/b/a CA Technologies) (Broadcom, Inc.)
• Original Assignee: Symantec Corporation (NortonLifeLock Inc.)
• Inventors: Dash, Sambit, Pai, Ramanath
• Primary Examiner(s): Cervetti, David Garcia
• Application Number:
  US13/902,194
• Publication Number:
  US 20140351587A1
• Time in Patent Office: 886 Days
• Field of Search: 713/165
• US Class Current: 1/1
• CPC Class Codes: G06F 21/44 Program or device authentication
• CPC Class Codes: H04L 2463/061 applying further key derivation, e.g. deriving traffic keys from a pair-wise master key
• CPC Class Codes: H04L 2463/062 applying encryption of the keys
• CPC Class Codes: H04L 63/0838 using one-time-passwords
• CPC Class Codes: H04L 63/0869 for achieving mutual authentication cryptographic mechanisms or cryptographic arrangements for mutual authentication H04L9/3273
• CPC Class Codes: H04W 12/04 Key management, e.g. using generic bootstrapping architecture [GBA]
• CPC Class Codes: H04W 12/068 using credential vaults, e.g. password manager applications or one time password [OTP] applications

Abstract

Techniques are disclosed for protecting cryptographic secrets stored locally in a device, such as a mobile phone. A client device creates or downloads a shared secret to be used in a server transaction. To protect this shared secret locally, the client device encrypts the shared secret using a key generated a file system attributes value, along with other sources of entropy. The file system attributes value may correspond to the inode of a file in a UNIX-based file system. Thereafter, when the shared secret is required for logical computation, the client device reconstructs the key using the file system attributes value and the other previous sources of entropy. The client device may use the key to decrypt the information and use the shared secret for its required purpose, e.g., in generating a one-time password for a login session.

Claims

1. A method for protecting a shared secret, the method comprising:

generating, by operation of a processor, a key based on at least a file system attribute of a file stored in a file system of a computing device, wherein the file system attribute of the file is an identifier assigned by the file system to uniquely identify the file stored in the file system of the computing device, and wherein the file system attribute is an inode of a file storing the shared secret in the file system;

encrypting the shared secret with the key; and

storing the encrypted shared secret in a storage memory on the computing device.

2. The method of claim 1, further comprising removing the key from the storage memory.

3. The method of claim 1, further comprising:

reconstructing the key based on the file system attribute;

decrypting the shared secret with the key; and

performing a computation with the shared secret.

4. The method of claim 3, wherein performing the computation comprises generating a one-time password in authenticating the client device to a server.

5. The method of claim 3, wherein performing the computation comprises sending the shared secret to a server in a challenge-response authentication.

6. The method of claim 3, wherein performing the computation comprises generating a one or more cryptographic keys with the shared secret.

7. A non-transitory computer-readable storage medium storing instructions, which, when executed on a processor, performs an operation for protecting a shared secret, the operation comprising:

generating, by operation of a processor, a key based on at least a file system attribute of a file stored in a file system of a computing device, wherein the file system attribute of the file is an identifier assigned by the file system to uniquely identify the file stored in the file system of the computing device, and wherein the file system attribute is an inode of a file storing the shared secret in the file system;

encrypting the shared secret with the key; and

storing the encrypted shared secret in a storage memory on the computing device.

8. The non-transitory computer-readable storage medium of claim 7, wherein the operation further comprises removing the key from the storage memory.

9. The non-transitory computer-readable storage medium of claim 7, the operation further comprising:

reconstructing the key based on the file system attribute;

decrypting the shared secret with the key; and

performing a computation with the shared secret.

10. The non-transitory computer-readable storage medium of claim 9, wherein performing the computation comprises generating a one-time password in authenticating the client device to a server.

11. The non-transitory computer-readable storage medium of claim 9, wherein performing the computation comprises sending the shared secret to a server in a challenge-response authentication.

12. The non-transitory computer-readable storage medium of claim 11, wherein performing the computation comprises generating a plurality of unique keys with the shared secret.

13. A system, comprising:

a processor and

a memory hosting an application, which, when executed on the processor, performs an operation for protecting a shared secret in a UNIX-based file system, the operation comprising;

generating, by operation of a processor, a key based on a file system attribute of at least a file stored in a file system of a computing device, wherein the file system attribute of the file is an identifier assigned by the file system to uniquely identify the file stored in the file system of the computing device, and wherein the file system attribute is an inode of a file storing the shared secret in the file system,

encrypting the shared secret with the key, and

storing the encrypted shared secret in a storage memory on the computing device.

14. The system of claim 13, wherein the operation further comprises removing the key from the storage memory.

15. The system of claim 13, the operation further comprising:

reconstructing the key based on the file system attribute;

decrypting the shared secret with the key; and

performing a computation with the shared secret.

16. The system of claim 15, wherein performing the computation comprises generating a one-time password in authenticating the client device to a server.

17. The system of claim 15, wherein performing the computation comprises sending the shared secret to a server in a challenge-response authentication.

18. The system of claim 15, wherein performing the computation comprises generating a plurality of unique keys with the shared secret.