CN107563228B

CN107563228B - Memory data encryption and decryption method

Info

Publication number: CN107563228B
Application number: CN201710657407.5A
Authority: CN
Inventors: 许海波; 应志伟; 杜朝晖
Original assignee: Haiguang Information Technology Co Ltd
Current assignee: Haiguang Information Technology Co Ltd
Priority date: 2017-08-03
Filing date: 2017-08-03
Publication date: 2021-04-20
Anticipated expiration: 2037-08-03
Also published as: CN107563228A

Abstract

The invention provides a memory data encryption and decryption method, and belongs to the technical field of data encryption processing. The method comprises S1, the processor module sending a key update request to the encryption module, the encryption module generating a new key after receiving the request; s2, for each encrypted memory page in the memory, the encryption module decrypts the memory page data corresponding to the encrypted memory page by using the old key, and re-encrypts each decrypted page data by using the new key. By using the memory data encryption and decryption method provided by the invention, malicious attacks caused by keeping an encryption key of an SME technology unchanged can be effectively reduced, so that the security of memory encryption is remarkably improved; and the flexibility of a security scheme is provided, and a user and a system can dynamically update the encryption and decryption keys according to needs.

Description

Memory data encryption and decryption method

Technical Field

The invention relates to the technical field of data encryption, in particular to a memory data encryption and decryption method.

Background

With the increasing complexity of modern computer systems and the increasing security requirements of computing environments due to emerging technologies such as cloud computing and big data in recent years, the industry is generally aware of the need to fully support the encryption function of data on the underlying hardware of the computer system. Among them, the CPU design and manufacturer in the united states proposed Secure Memory Encryption (SME) technology (see [1] AMD Memory Encryption White Paper; [2] cryptographic protection of information in processing systems (patent: CN 106062768A)). In the technology, a memory encryption module is added on the basis of the existing CPU hardware, so that data are encrypted and then written into a memory; when the CPU needs to read data, the encryption module automatically decrypts the encrypted data, and the whole process is completely transparent to upper-layer software. The method can effectively resist the data leakage problem caused by physical attack to the memory, isolation failure caused by software defects and the like. However, in this method, since the encrypted security key remains unchanged after running on the system, it is easy for a malicious attacker to perform cryptographic attack and cracking against the weakness of the encryption method. The above security risks presented by SME are especially evident in the use scenario of SEV as the basis of the SEV ([1] AMD Memory Encryption white te Paper) scheme.

Fig. 1 shows a structure diagram of a conventional SME scheme, in which security information is isolated by using a hardware encryption module 2 in an access path of a memory module. Where the encryption module 2 is located in the memory control module 3 and provides an indication to the processor module 1 whether or not each access is a secure access. The encryption key in the graph is automatically generated when the system is powered on and remains unchanged in the whole system operation process, which easily causes a malicious attacker to implement password attack and crack aiming at the weakness of the encryption method.

Disclosure of Invention

The invention provides a memory data encryption and decryption method, which solves the problem of malicious attack caused by the fact that an encryption key is kept unchanged.

The invention provides a memory data encryption and decryption method, which comprises the following steps:

s1, the processor module sends a key updating request to the encryption module, and the encryption module generates a new key after receiving the request;

s2, for each encrypted memory page in the memory, the encryption module decrypts the memory page data corresponding to the encrypted memory page by using the old key, and re-encrypts each decrypted page data by using the new key.

Wherein, step S1 is preceded by: the operating system checks the current state of the processor module, and if the processor module is busy, the operating system directly exits;

if the processor module is in the idle state, the operating system is suspended, no input-output operation of any other process is accepted, and the above-described steps S1 and S2 are performed.

In addition, after the steps are successfully executed, the operating system returns to success; if an error occurs in the above steps, the operating system returns to error and ends the updating process.

Step S1 further includes the encryption module saving the new key to the register of the memory controller module or its internal EEPROM.

In step S1, the processor module sends a key update request to the encryption module via the key update interface.

Preferably, the processor module sends the key update request to the cryptographic module in step S1 by a new machine instruction, or the controller Firmware (FW) providing a new application programming interface.

By using the memory data encryption and decryption method provided by the invention, malicious attacks caused by keeping an encryption key of an SME technology unchanged can be effectively reduced, so that the security of memory encryption is remarkably improved; and the flexibility of a security scheme is provided, and a user and a system can dynamically update the encryption and decryption keys according to needs.

Drawings

FIG. 1 is a schematic diagram of a conventional SME scheme;

FIG. 2 is a diagram of a system for increasing security of memory encryption by dynamically updating encryption keys;

fig. 3 is a flowchart of a method for encrypting and decrypting memory data according to an embodiment of the present invention.

Detailed Description

The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.

As shown in fig. 2 and 3, the present invention provides a method for encrypting and decrypting memory data, wherein the method comprises:

s1, the processor module 1 sends a key updating request to the encryption module 2, and the encryption module generates a new key after receiving the request;

s2, for each encrypted memory page in the memory, the encryption module 2 decrypts the memory page data corresponding to the encrypted memory page by using the old key, and re-encrypts each decrypted page data by using the new key.

Because the updating of the encryption key can cause the invalidation of the current encrypted data in the memory, the encrypted data in the memory needs to be decrypted after the key is updated successfully, and then the new key is used for encryption storage again. When the system is in a full-load operation state, the system has a large amount of data stored in the memory. If the key is updated at this point, it will take a long time to decrypt/encrypt the data in memory, which may result in the system being unavailable for a long period of time.

Therefore, in a preferred embodiment of the present invention, step S1 is preceded by: the operating system checks the current state of the processor module 1, and if the processor module 1 is busy, the operating system directly exits;

if the processor module 1 is in the idle state, the operating system is suspended, no input-output operation of any other process is accepted, and the above-described steps S1 and S2 are performed.

Step S1 further includes the encryption module saving the new key to the register in the memory controller module or its internal EEPROM.

A system for increasing memory encryption security by dynamically updating encryption keys is shown in fig. 2. The system supports the dynamic updating function of the encryption KEY by passing a KEY updating interface (shown as an interface by a dotted line in fig. 3, the implementation form includes a hardware instruction UPDATE _ MEM _ KEY, the encryption module FW provides a new API, etc.) between the processor module 1 and the encryption module 2. After the function is added, the operating system can send a key update request to the cryptographic module 2 at an appropriate timing to generate a new cryptographic key. Further, the processor module 1 realizes sending the key update request to the cryptographic module 2 by a new machine instruction, or by the controller Firmware (FW) providing a new Application Programming Interface (API), in step S1.

In the foregoing embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.

Those of skill would further appreciate that the various illustrative components and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied in hardware, a software module executed by a processor, or a combination of the two. A software module may reside in Random Access Memory (RAM), memory, Read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

The above embodiments are provided to further explain the objects, technical solutions and advantages of the present invention in detail, it should be understood that the above embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A method for dynamically updating a memory encryption key, the method comprising:

s1, the processor module sends a key updating request to the encryption module of the memory controller, and the encryption module generates a new key after receiving the request;

s2, for the encrypted memory page in the memory, the encryption module decrypts the encrypted memory page using the old key, and re-encrypts the decrypted memory page using the new key;

step S1 is preceded by: the operating system checks the current state of the processor module, and if the processor module is busy, the operating system directly exits; if the processor module is in the idle state, the operating system is suspended, no input-output operation of any other process is accepted, and the above-described steps S1 and S2 are performed.

2. The method of claim 1, wherein after the steps are successfully performed, the operating system returns a "success"; if an error occurs in the above steps, the operating system returns to error and ends the updating process.

3. The method of claim 1, wherein step S1 further comprises the encryption module saving the new key to a register or EEPROM in the memory controller module.

4. The method of claim 1, wherein the processor module is configured to send the rekeying request to the cryptographic module via the rekeying interface in step S1.

5. The method of claim 1, wherein the processor module sends the key update request to the cryptographic module in step S1 via a new machine instruction or a new application programming interface provided by the controller firmware.

6. A system for dynamically updating memory encryption keys, comprising:

a processor module, and

the memory controller comprises an encryption module and a memory, wherein the encryption module is used for encrypting and decrypting memory pages in the memory, the memory stores a secret key,

wherein the processor module is configured to send a key update request to the cryptographic module, the cryptographic module is configured to generate a new key upon receipt of the request and to store the new key to the memory,

the encryption module decrypts the encrypted memory page by using an old key and re-encrypts the decrypted memory page by using the new key;

the operating system checks the current state of the processor module, and directly exits if the processor module is busy; if the processor module is in an idle state, the operating system is suspended, does not accept input-output operations of any other process, and executes the processor module.

7. The system of claim 6, wherein the memory is a register or an EEPROM.