Cryptographically protected paging system

• US 7,149,901 B2
• Filed: 01/29/2004
• Issued: 12/12/2006
• Est. Priority Date: 12/12/1996
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Herbert, Howard C., Davis, Derek L.
• Primary Examiner(s): Arani, Taghi T.
• Application Number:
  US10/768,902
• Publication Number:
  US 20040186994A1
• Time in Patent Office: 1,048 Days
• Field of Search: 713/177, 713/189, 713/190, 713/193, 713/194, 713/201, 713/200, 380/25, 380/30, 711/163, 711/164, 711/167, 726/16
• US Class Current: 713/190
• CPC Class Codes: G06F 12/08 in hierarchically structured memory systems, e.g. virtual memory systems
• CPC Class Codes: G06F 12/1408 by using cryptography for digital transmission H04L9/00
• CPC Class Codes: G06F 21/64 Protecting data integrity, e.g. using checksums, certificates or signatures
• CPC Class Codes: G06F 21/79 in semiconductor storage media, e.g. directly-addressable memories
• CPC Class Codes: G06F 21/86 Secure or tamper-resistant housings
• CPC Class Codes: G06F 2212/251 Local memory within processor subsystem
• CPC Class Codes: G06F 2212/253 Centralized memory
• CPC Class Codes: G06F 2221/2107 File encryption
• CPC Class Codes: H04L 9/3236 using cryptographic hash functions
• CPC Class Codes: H04L 9/3247 involving digital signatures

Abstract

A method and system for maintaining integrity and confidentiality of pages paged to an external storage unit from a physically secure environment. An outgoing page is selected to be exported from a physically secure environment to an insecure environment. An integrity check value is generated and stored for the outgoing page. In one embodiment, this takes the form of taking a one-way hash of the page using a well-known one-way hash function. The outgoing page is then encrypted using a cryptographically strong encryption algorithm. Among the algorithms that might be used in one embodiment of the invention are IDEA and DES. The encrypted outgoing page is then exported to the external storage. By virtue of the encryption and integrity check, the security of the data on the outgoing page is maintained in the insecure environment.

Claims

1. A method comprising:

importing encrypted incoming information into a physically secure environment from an external storage unit of a physically insecure environment;

decrypting the encrypted incoming information within the physically secure environment;

calculating an integrity check value for the incoming information within the physically secure environment;

comparing the integrity check value of the incoming information with a previously stored

integrity check value corresponding to the incoming information from within the physically secure environment;

discarding the incoming information when the calculated integrity check value does not match the previously stored integrity check value of the incoming information;

storing the incoming information within the physically secure environment when the calculated integrity check value matches the previously stored integrity check value of the incoming information; and

processing the stored, incoming information within the physically secure environment.

2. The method of claim 1, wherein prior to importing incoming encrypted information, the method further comprising:

generating an integrity check value for outgoing information within the physically secure environment;

storing the integrity check value for the outgoing information within the physically secure environment;

encrypting the outgoing information within the physically secure environment; and

exporting the encrypted outgoing information outside the physically secure environment to an external storage unit within an insecure environment.

3. The method of claim 2 wherein the encrypted outgoing information is encrypted using a symmetric encryption algorithm.

4. The method of claim 2 wherein the generating of the integrity check value comprises:

one way hashing the outgoing information; and

storing a predetermined portion of a hash value of the outgoing information in a location within the physically secure environment.

5. The method of claim 3 further comprising:

retrieving a random key for use in encrypting the outgoing information.

6. The method of claim 5 wherein outgoing information related to a single application is encrypted using a same key.

7. The method of claim 5 wherein a different key is generated for encrypting each portion of outgoing information.

8. The method of claim 5 further comprising:

storing the key in a table in the physically secure environment.

9. The method of claim 4 wherein the location is pointed to by a pointer in a field of a page table entry corresponding to the outgoing information.

10. The method of claim 4 wherein the predetermined portion is the whole hash value.

11. The method of claim 10 wherein outgoing information related to a single application is encrypted using a same key.

12. The method of claim 10 wherein a different key is generated for encrypting each portion of outgoing information.

13. The method of claim 10 further comprising:

storing the key in a table in the physically secure environment.

14. The method of claim 9 wherein the predetermined portion is the whole hash value.