Secure repository with layers of tamper resistance and system and method for providing same

• US 7,958,373 B2
• Filed: 05/14/2009
• Issued: 06/07/2011
• Est. Priority Date: 06/27/2000
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Marr, Michael David, Manferdelli, John L., Krishnaswamy, Vinay, Jakubowski, Mariusz H.
• Primary Examiner(s): Brown; Christopher J
• Application Number:
  US12/466,295
• Publication Number:
  US 20090228718A1
• Time in Patent Office: 754 Days
• Field of Search: 713/189, 380/277
• US Class Current: 713/189
• CPC Class Codes: G06F 21/1066 Hiding content
• CPC Class Codes: G06F 21/14 against software analysis or reverse engineering, e.g. by obfuscation
• CPC Class Codes: G06F 2211/007 Encryption, En-/decode, En-/decipher, En-/decypher, Scramble, (De-)compress
• CPC Class Codes: G06F 2221/2107 File encryption

Abstract

A secure repository individualized for a hardware environment and a method and system for providing the same. The secure repository includes a hidden cryptographic key and code that applies the key without requiring access to a copy of the key. The code that implements the secure repository is generated in a manner that is at least partly based on a hardware ID associated with the hardware environment in which the secure repository is to be installed, and may also be based on a random number. Cryptographic functions implemented by the secure repository include decryption of encrypted information and validation of cryptographically signed information. The secure repository may be coupled to an application program, which uses cryptographic services provided by the secure repository, by way of a decoupling interface that provides a common communication and authentication interface for diverse types of secure repositories. The decoupling interface may take the form of a single application programmer interface (API) usable with multiple dynamically linkable libraries.

Claims

1. A method implemented at least in part by a computing device of securely decrypting data with a cryptographic key, said method comprising:

identifying attributes of said cryptographic key corresponding to a set of actions;

performing a first set of actions functionally equivalent to the actions corresponding to said cryptographic key using said attributes but without access to, storing in memory, or exposing a whole or segment of said cryptographic key; and

performing a diversionary second set of actions different from said first set of actions;

wherein said first and said second sets of actions are implemented by way of a set of computer-executable instructions executable on a computing device.

2. The method of claim 1, wherein performance of said first set of actions does not depend on performance of said diversionary second set of actions.

3. The method of claim 1, wherein either of said first or second sets of actions in some manner relies for its performance on retrieval or derivation from said computing device of hardware identification data which identifies or in some way relates to hardware associated with said computing device.

4. The method of claim 1, further comprises the acts of:

detecting a modification or deletion of at least a portion of said set of computer-executable instructions; and

restoring said set of instructions to its state prior to said modification or deletion.

5. The method of claim 1, further comprises the act of decrypting at least a portion of said set of computer-executable instructions prior to executing said portion.

6. The method of claim 5, further comprising the act of re-encrypting said portion subsequent to executing said portion.

7. The method of claim 1, further comprising the acts of:

deriving a value based on at least a portion of said set of computer-executable instructions; and

comparing the derived value to a stored value.

8. The method of claim 7, wherein said act of deriving comprises the act of hashing said portion.

9. The method of claim 1, further comprising the act of moving at least some of said computer-executable instructions to a randomly or pseudo-randomly selected memory location on said computing device prior to execution of the moved instructions.

10. A computer-readable storage medium, wherein the computer-readable storage medium is not a signal, encoded with computer-executable instructions to perform the acts comprising:

identifying attributes of said cryptographic key corresponding to a set of actions;

performing a first set of actions functionally equivalent to the actions corresponding to said cryptographic key using said attributes but without access to, storing in memory, or exposing a whole or segment of said cryptographic key; and

performing a diversionary second set of actions different from said first set of actions;

wherein said first and said second sets of actions are implemented by way of a set of computer-executable instructions executable on a computing device.