Verifying integrity of backup file in a multiple operating system environment

Patent metadata

Field	Value
Publication number	US-2016012233-A1
Application number	US-201414330862-A
Country	US
Kind code	A1
Filing date	Jul 14, 2014
Priority date	Jul 14, 2014
Publication date	Jan 14, 2016
Grant date	—

Abstract

Provided is a technique to enhance security of a computer in a multi-OS operating environment. A memory image of a primary OS is in an active state, and a memory image of a secondary OS is in a non-active state. When switching is performed from the primary OS to the secondary OS, a runtime image is created, and a digest P is calculated and encrypted (C). When switching is performed from the secondary OS to the primary OS, a digest of the stopped runtime image is calculated. Only when comparison between the decrypted digest P and the calculated digest shows agreement, is switching of the primary OS allowed.

First claim

What is claimed is:

1 . A method comprising:
in response to switching operation of a computer from a first operating environment to a second operating environment, encrypting a representative file enabling verification of identity of at least a portion of a first memory image, the first memory image corresponding to the first operating environment; saving the first memory image at a selected location; decrypting the encrypted representative file in response to switching operation from the second operating environment to the first operating environment; and comparing a file representative of the saved first memory image with the decrypted representative file.

2 . The method of claim 1 , wherein the representative file is a digest that is created by hashing at least a portion of the first memory image

3 . The method of claim 1 , wherein a system firmware causes the computer to execute the encrypting, the saving, the decrypting and the comparing.

4 . The method of claim 3 , wherein the encrypting includes using an encryption key that is stored at a SMRAM area.

5 . The method of claim 3 , wherein the encrypting includes:
creating a public key and an encrypted private key; and storing a decrypted private key at a SMRAM area.

6 . The method of claim 5 , wherein encryption and decryption of the private key is performed by a security chip.

7 . The method of claim 3 , wherein the encrypting and the decrypting include using a common key that is stored in a non-volatile memory, which is accessible only to the system firmware.

8 . The method of claim 1 , wherein the selected location is an address space of a system memory that is divided from a physical address space where the second operating environment operates.

9 . The method of claim 1 , wherein the selected location is a disk drive that stores boot images of the first operating environment and the second operating environment.

10 . The method of claim 1 , further comprising:
in response to switching operation from the second operating environment to the first operating environment, encrypting a representative file enabling verification of identity of at least a portion of a second memory image, the second memory image corresponding to the second operating environment; saving the second memory image at a selected location; decrypting the encrypted representative file in response to switching operation from the first operating environment to the second operating environment; and comparing a file representative of the saved second memory image with the decrypted representative file.

11 . The method of claim 1 , further comprising:
decrypting the encrypted representative file before the operating environment transits to an active state in response to a resume operation; and stopping the resumption when the decrypted representative file and a representative file extracted from the memory image kept in the non-active state do not agree.

12 . The method of claim 11 , wherein encrypting a representative file includes:
transitioning to an execution environment of a system firmware in response to the switching operation; and operating the system firmware to make the computer implement a function to encrypt the representative file and decrypt the representative file.

13 . The method of claim 12 , wherein the system firmware causes the computer to implement a function to compare the decrypted representative file and a representative file that is extracted from the memory image kept in a non-active state.

14 . A program product comprising a computer readable storage medium that stores code executable by a processor to perform:
in response to switching operation from the first operating environment to the second operating environment, encrypting a representative file enabling verification of identity of at least a portion of a first memory image, the first memory image corresponding to the first operating environment; saving the runtime image at a selected location; decrypting the encrypted representative file in response to switching operation from the second operating environment to the first operating environment; and comparing a file representative of the saved first memory image with the decrypted representative file.

15 . The program product of claim 14 , wherein the code is further executable to perform encrypting and the decrypting include using a common key that is stored in a non-volatile memory, which is accessible only to the system firmware.

16 . The computer program of claim 14 , wherein the code is further executable to
decrypting the encrypted representative file before resuming the operating environment in response to a resume operation; and
stopping the resumption when the decrypted representative file and a representative file extracted from the memory image kept in a saved state do not agree.

17 . A computer capable of operating in any one of a plurality of operating environments, comprising:
a processor; a volatile memory that stores a program executed by the processor; a disk drive that stores a plurality of operating systems that can be booted; a user interface enabling switching operation;
an encryption unit that encrypts a representative file that is extracted from a memory image stored in the volatile memory in response to switching operation from a first operating environment to a second operating environment;
a save unit that saves the memory image at a predetermined place; a decryption unit that decrypts the encrypted representative file in response to switching operation from the second operating environment to the first operating environment; and a comparison unit that compares a representative file extracted from the saved memory image with the decrypted representative file.

18 . The computer of claim 17 , further comprising a non-volatile memory that stores a system firmware including a module making up the encryption unit and the decryption unit.

19 . The computer of claim 18 , further comprising a security chip that encrypts a key to encrypt the representative file and decrypts the key using values stored secure registers in response to a request from the system firmware.

20 . The computer of claim 17 , wherein the selected location is a non-volatile storage that is different from the disk drive.

Assignees

• Lenovo Singapore Pte Ltd

Inventors

• Kawano Seiichi
• Oka Kenji
• Springfield Randall Scott

Classifications

• H04L9/0897

  involving additional devices, e.g. trusted platform module [TPM], smartcard or USB · CPC title

• G06F9/441

  Multiboot arrangements, i.e. selecting an operating system to be loaded · CPC title

• H04L9/3234

  involving additional secure or trusted devices, e.g. TPM, smartcard, USB or software token (network architectures or network communication protocols for supporting authentication of entities using an additional device in a packet data network H04L63/0853) · CPC title

• H04L9/0825

  using asymmetric-key encryption or public key infrastructure [PKI], e.g. key signature or public key certificates · CPC title

• G06F21/575 Primary

  Secure boot · CPC title