INFORMATION PROCESSING DEVICE AND COMPUTER PROGRAM PRODUCT

• US 20140298026A1
• Filed: 01/08/2014
• Published: 10/02/2014
• Est. Priority Date: 03/26/2013
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: ISOZAKI, Hiroshi, Kanai, Jun
• Granted Patent: US 9,191,202 B2
• Time in Patent Office: Days
• US Class Current: 713/171
• CPC Class Codes: G06F 21/53 by executing in a restricted environment, e.g. sandbox or secure virtual machine
• CPC Class Codes: G06F 21/604 Tools and structures for managing or administering access control systems
• CPC Class Codes: G06F 21/6281 at program execution time, where the protection is within the operating system
• CPC Class Codes: G06F 21/70 Protecting specific internal or peripheral components, in which the protection of a component leads to protection of the entire computer
• CPC Class Codes: H04L 9/0822 using key encryption key
• CPC Class Codes: H04L 9/0825 using asymmetric-key encryption or public key infrastructure [PKI], e.g. key signature or public key certificates
• CPC Class Codes: H04L 9/0897 involving additional devices, e.g. trusted platform module [TPM], smartcard or USB
• CPC Class Codes: H04L 9/3234 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 Class Codes: H04L 9/3236 using cryptographic hash functions
• CPC Class Codes: H04L 9/3247 involving digital signatures

Abstract

According to an embodiment, a device includes a processor unit, a control unit, a setting unit, a writing unit, and an executing unit. The processor unit is configured to switch between secure and non-secure modes, read/write data from/to a memory unit, and write an OS execution image of a secure OS unit to the memory unit. The setting unit is configured to set a shared memory area allowing reading and writing in both modes and an execution module memory area allowing reading and writing in the secure mode but not allowing reading or writing in the non-secure mode with respect to the control unit. The writing unit is configured to write an execution module to be executed in the secure OS unit to the shared memory area. The executing unit is configured to execute the execution module that has been written to the execution module memory area.

Claims

1. An information processing device comprising:

a main memory unit configured to store data;

a main processor unit configured to

selectively switch between a secure mode and a non-secure mode,

read and write data from and to the main memory unit, and

write an OS execution image to the main memory unit, the main processor unit including a state sending unit for sending state information indicating the present mode to a bus;

a secure OS unit configured to be executed by the main processor unit in the secure mode;

an execution module configured to be executed by the main processor unit in the secure mode;

a non-secure OS unit configured to be executed by the main processor unit in the non-secure mode;

a secure monitor memory setting unit configured to set a shared memory area and an execution module memory area, the shared memory allowing reading and writing in the secure mode and the non-secure mode of the main processor unit, the execution module memory area allowing reading and writing in the secure mode of the main processor unit but not allowing reading or writing in the non-secure mode of the main processor unit;

an address space control unit configured to

determine the mode of the main processor unit based on the state information received from the bus, and

control allowing and disallowing of reading and writing with respect to the main memory unit from the main processor unit according to settings performed by the secure monitor memory unit;

a shared memory area writing unit configured to write an execution module to be executed in the secure OS unit to the shared memory area of the main memory unit;

an execution module loading unit configured to write the execution module that has been written to the shared memory area, to the execution module memory area; and

an application executing unit configured to execute the execution module that has been written to the execution module memory area.

2. The device according to claim 1, further comprising a command selecting unit configured to determine whether a command issued by the non-secure OS unit to the secure OS unit indicates writing of the execution module to the execution module memory area of the main memory unit or indicates execution of the execution module, wherein

the execution module loading unit is configured to write the execution module that has been written to the shared memory area, to the execution module memory area when a command issued by the non-secure OS unit indicates writing of the execution module to the execution module memory area of the main memory unit,

the application executing unit is configured to execute the execution module that has been written to the execution module memory area when a command issued by the non-secure OS unit indicates execution of the execution module,

the shared memory area writing unit is configured to be executed in the non-secure mode, and

the execution module loading unit and the application executing unit are configured to be executed in the secure mode.

3. The device according to claim 1, further comprising

a command selecting unit configured to determine whether a command issued by the non-secure OS unit to the secure OS unit indicates verification of a signature of the execution module,

a hash value calculator configured to calculate a hash value of the execution module that has been written to the execution module memory area and store the calculated hash value therein;

a verification unit configured to verify a signature of the execution module using the calculated hash value and a public key when the command selecting unit determines that a command issued by the non-secure OS unit indicates verification of a signature of the execution module, and

the verification unit and the hash value calculator are configured to be executed in the secure mode.

4. The device according to claim 1, further comprising:

a key storing unit configured to store a common key;

a key generating unit configured to generate a secret key and a public key;

a data encrypting unit configured to write an encrypted secret key obtained by encrypting the secret key using the common key stored in the key storing unit, and a public key to the shared memory area; and

a module signature generating unit configured to read data from the shared memory area, and generate a signature using the read data and the secret key, wherein

the data encrypting unit and the module signature generating unit are configured to be executed in the secure mode.

5. The device according to claim 3, further comprising:

a second key storing unit configured to store a second common key; and

a second data encrypting unit configured to

encrypt data using the hash value of the execution module as calculated by the hash value calculator and using the second common key stored in the second key storing unit, and

write the encrypted data to the shared memory area, wherein

the second data encrypting unit is configured to be executed in the secure mode.

6. The device according to claim 1, further comprising

a timer handler unit configured to

detect a timer interrupt, and

switch the main processor unit from one mode to another mode every time a predetermined time period elapses.

7. An information processing device comprising:

a main memory unit configured to store data;

a main processor unit configured to selectively switch between a secure mode and a non-secure mode, the main processor unit including a state sending unit for sending state information indicating the present mode to a bus;

a secure OS unit configured to be executed by the main processor unit in the secure mode;

a non-secure OS unit configured to be executed by the main processor unit in the non-secure mode;

a secure monitor memory setting unit configured to set a shared memory area and a non-secure OS unit memory area, the shared memory allowing reading and writing in the secure mode and the non-secure mode of the main processor unit, the non-secure OS unit memory area allowing writing an OS execution image of the non-secure OS unit;

an address space control unit configured to

determine the mode of the main processor unit based on the state information received from the bus, and

control allowing and disallowing of reading and writing with respect to the main memory unit from the main processor unit according to settings performed by the secure monitor memory unit;

a shared memory area writing unit configured to write an execution module to be executed in the secure OS unit to the shared memory area of the main memory unit;

a boot loader unit configured to write the OS execution image of the non-secure OS unit to a predetermined memory area of the main memory unit in the non-secure mode at the time of booting of the device, wherein

the secure OS unit is configured to

compare a hash value calculated from the OS execution image of the non-secure OS unit that has been written to the non-secure OS unit memory area, with an expected value of the hash value of the OS execution image of the non-secure OS unit, and

determine that the data of the non-secure OS unit is correct and allow execution of the non-secure OS unit when the hash value and the expected value are identical.

8. The device according to claim 7, wherein

the secure monitor memory setting unit is configured to allow writing to the non-secure OS unit memory area in the secure mode but not allow writing to the non-secure OS unit memory area in the non-secure mode,

the boot loader unit is configured to write the OS execution image of the non-secure OS unit to the shared memory area, and

the secure OS unit is configured to copy a first portion of the OS execution image of the non-secure OS unit from the shared memory area to the non-secure OS unit memory area, the first portion being a portion from which calculation of the hash value is completed.

9. The device according to claim 7, further comprising a monitor handler unit configured to perform exception processing to switch from the non-secure mode to the secure mode when an access that is not allowed is attempted in the address space control unit, wherein

the secure monitor memory setting unit is configured to set the non-secure OS unit memory area as a memory area that is allowed to be accessed for reading but not allowed to be accessed for writing in the non-secure mode,

the boot loader unit is configured to send a command to write the OS execution image of the non-secure OS unit to the non-secure OS unit memory area in the non-secure mode at the time of booting,

the monitor handler unit is configured to switch to the secure mode and hand over operations to the secure OS unit when the command for writing to the non-secure OS unit memory area is sent by the boot loader unit, and

the secure OS unit is configured to copy the OS execution image of the non-secure OS unit to the non-secure OS unit memory area in the secure mode.

10. The device according to claim 7, further comprising

a timer handler unit configured to

detect a timer interrupt, and

switch the main processor unit to the secure mode every time a predetermined time period elapses, wherein

the secure OS unit is configured to

calculate the hash value for a portion of the OS execution image of the non-secure OS unit stored in the main memory unit for which hash value calculation is not yet completed when the timer handler unit performs operations for the timer interrupt, and

switch the main processor unit back to the non-secure mode that was present prior to the start of the operations for the timer interrupt upon completion of the hash value calculation.

11. The device according to claim 7, further comprising

a timer handler unit configured to

detect a timer interrupt, and

switch the main processor unit to the secure mode every time a predetermined time period elapses, wherein

the secure OS unit is configured to

calculate the hash value of the OS execution image of the non-secure OS unit stored in the main memory unit,

compare the hash value with an expected value of the hash value of the OS execution image of the non-secure OS unit, and

identify that the non-secure OS unit has been altered and instruct the non-secure OS unit to perform predetermined error processing when the hash value and the expected value are not identical.

12. A computer program product comprising a computer-readable medium containing a program executed by a computer that includes a main memory unit configured to store data, and a main processor unit configured to selectively switch between a secure mode and a non-secure mode, read and write data from and to the main memory unit, and write an OS execution image to the main memory unit, the main processor unit including a state sending unit for sending state information indicating the present mode to a bus, the program causing the computer to execute:

executing, by the main processor unit, a secure OS unit in the secure mode;

executing, by the main processor unit, an execution module in the secure mode;

executing, by the main processor unit, a non-secure OS unit in the non-secure mode;

setting a shared memory area and an execution module memory area, the shared memory allowing reading and writing in the secure mode and the non-secure mode of the main processor unit, the execution module memory area allowing reading and writing in the secure mode of the main processor unit but not allowing reading or writing in the non-secure mode of the main processor unit;

determining the mode of the main processor unit based on the state information received from the bus;

controlling allowing and disallowing of reading and writing with respect to the main memory unit from the main processor unit according to the settings;

writing the execution module to be executed in the secure OS unit to the shared memory area of the main memory unit;

writing the execution module that has been written to the shared memory area, to the execution module memory area; and

executing the execution module that has been written to the execution module memory area.

13. The computer program product according to claim 12, the program further causing the computer to execute

determining whether a command issued by the non-secure OS unit to the secure OS unit indicates writing of the execution module to the execution module memory area of the main memory unit or indicates execution of the execution module, wherein

upon writing the execution module, writing the execution module that has been written to the shared memory area, to the execution module memory area when a command issued by the non-secure OS unit indicates writing of the execution module to the execution module memory area of the main memory unit, and

upon executing the execution module, executing the execution module that has been written to the execution module memory area when a command issued by the non-secure OS unit indicates execution of the execution module, wherein

the writing the execution module to be executed in the secure OS unit is executed in the non-secure mode, and

the writing the execution module to the execution module memory area and the executing the execution module are executed in the secure mode.

14. The computer program product according to claim 12, the program further causing the computer to execute

determining whether a command issued by the non-secure OS unit to the secure OS unit indicates verification of a signature of the execution module,

calculating a hash value of the execution module that has been written to the execution module memory area and store the calculated hash value therein;

and

verifying a signature of the execution module using the calculated hash value and a public key when the command selecting unit determines that a command issued by the non-secure OS unit indicates verification of a signature of the execution module, wherein

the calculating the hash value and the verifying the signature are executed in the secure mode.

15. The computer program product according to claim 12, the program further causing the computer to execute

storing a common key to a key storing unit;

generating a secret key and a public key;

writing an encrypted secret key obtained by encrypting the secret key using the common key stored in the key storing unit, and a public key to the shared memory area;

reading data from the shared memory area; and

generating a signature using the read data and the secret key, wherein

the writing the encrypted secret key and the generating the signature executed in the secure mode.

16. The computer program product according to claim 14, the program further causing the computer to execute

storing a second common key to a second key storing unit;

encrypting data using the hash value of the execution module as calculated by the hash value calculator and using the second common key stored in the second key storing unit, and

writing the encrypted data to the shared memory area, wherein

the encrypting the data is executed in the secure mode.

17. The computer program product according to claim 12, the program further causing the computer to execute

detecting a timer interrupt, and

switching the main processor unit from one mode to another mode every time a predetermined time period elapses.