WO2022227273A1

WO2022227273A1 - Smart card protection method and apparatus capable of side channel attack resistance

Info

Publication number: WO2022227273A1
Application number: PCT/CN2021/104178
Authority: WO
Inventors: 张新访; 董逢华; 胡瑞璟; 肖灵; 苏昆
Original assignee: 武汉天喻信息产业股份有限公司
Priority date: 2021-04-30
Filing date: 2021-07-02
Publication date: 2022-11-03
Also published as: CN113127940A

Abstract

The present invention relates to a smart card protection method and apparatus capable of side channel attack resistance. The method comprises the following steps: calculating a security policy sequence number according to a security policy sequence mark and a policy factor; calling a corresponding security policy in an application layer of a smart card according to the security policy sequence number; and executing the corresponding security policy in the application layer. Security requirements can be met on chips with different security levels by means of an application layer of a smart card merely calling, before and after an important process, a security policy by means of a smart card protection apparatus capable of side channel attack resistance, such that the difficulty of adding security processing to an application is reduced, and by means of hiding the process between random security policies, a capability of the smart card to resist a side channel attack is enhanced.

Description

A kind of smart card anti-side channel attack protection method and device

technical field

The present invention relates to the field of smart cards, in particular to a method and device for protecting smart cards against side channel attacks.

Background technique

With the increasing popularity of smart cards, the application of smart cards has spread to all aspects of people's lives. A smart card is a general term for a plastic card with a microchip embedded in it. A smart card requires data interaction through a reader and may be subject to side-channel attacks in the process. Side-channel attack is an attack method that utilizes the information leaked by the smart card during the operation process. The power consumption attack is a common attack method currently used by attackers. This type of attack is represented by differential power analysis (side channel). The attack method collects the power consumption information of the chip in the encryption operation of the smart card, and then processes and analyzes the power consumption information to obtain useful information about the cracking.

In the related art, security processing methods are generally added at the chip layer of the smart card or the COS (Chip Operating System, on-chip operating system) layer of the smart card to prevent various side-channel attacks. Because different chips or different COS layers implement different protection methods, it is difficult to ensure that all key processes can meet the security requirements, so new security processing methods need to be added.

However, implementing the security protection strategy will inevitably pay the cost of code length, computing time, RAM (Random Access Memory, random access memory) space, etc. If too much security processing is added, it will increase the difficulty of application development and debugging. This will affect the availability of smart cards.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a smart card anti-side channel attack protection method and device, so as to solve the inconsistency in the implementation of different chip layers or COS layers in related technologies, and it is difficult to ensure that all key processes can meet the security requirements, so it is necessary to add new Security processing method, but if too much security processing is added, it will increase the difficulty of application development and debugging.

A first aspect provides a smart card anti-side channel attack protection method, a smart card anti-side channel attack protection method, characterized in that it includes the following steps: calculating a security policy sequence number according to a security policy sequence mark and a policy factor; The security policy serial number invokes the corresponding security policy in the application layer of the smart card; the application layer executes the corresponding security policy.

In some embodiments, before calculating the security policy sequence number according to the security policy sequence tag and the policy factor, the method further includes: acquiring the security policy sequence tag, wherein the security policy sequence tag is a random number.

In some embodiments, the security policy includes one or more types of security policies, and before invoking the corresponding security policy in the application layer of the smart card according to the security policy sequence number, including: performing one or more of the security policies in sequence. Numbering.

In some embodiments, the security policies include one or more types, each of the security policies has a corresponding number, and the invoking the corresponding security policies in the application layer of the smart card according to the security policy sequence number includes: when When the security policy serial number is the same as the security policy number, the security policy corresponding to the number is invoked.

In some embodiments, the calculating the security policy sequence number according to the security policy sequence mark and the policy factor includes: taking the remainder of the security policy sequence mark and the policy factor to obtain the security policy sequence number; wherein, the security policy sequence number The tag includes at least one byte, and each byte takes the remainder of the policy factor to obtain the security policy sequence number, and the policy factor is a preset positive integer.

In some embodiments, the security policy includes one or more types, and executing the corresponding security policy at the application layer includes: judging whether the corresponding security policy is enabled according to the security policy enable flag, and if so, executing the corresponding security policy. The corresponding security policy; wherein, the security policy enable flag includes at least one bit, each bit corresponds to one of the security policies, and when the bit is 1, the corresponding security policy is on state; when the bit is 0, the corresponding security policy is in a closed state.

In some embodiments, the security policy includes one or more of increasing random delay, increasing algorithm operation, performing a write operation to a specific address, or increasing a specific data operation according to the input factor of the security policy, wherein the security The policy input factor is a random number.

In some embodiments, after the application layer executes the corresponding security policy, the method further includes: executing an application process; and executing the above-mentioned smart card anti-side-channel attack protection method again.

In a second aspect, a smart card anti-side channel attack protection device is provided, which includes: a calculation module for calculating a security policy sequence number according to a security policy sequence mark and a policy factor; a calling module for calculating a security policy sequence number according to the security policy sequence number The corresponding security policy in the application layer of the smart card is called; the execution module is used for executing the corresponding security policy in the application layer.

In some embodiments, the smart card anti-side channel attack protection device further includes an acquisition module configured to acquire the security policy sequence mark, wherein the security policy sequence mark is a random number.

In a third aspect, a computer device is provided, the computer device includes a processor and a memory, the memory stores at least one piece of program code, the program code is loaded and executed by the processor to implement the above smart card Anti-side channel attack protection method.

In a fourth aspect, a computer-readable storage medium stores at least one piece of program code, the program code is loaded and executed by a processor to implement the above-mentioned smart card anti-side-channel attack protection method.

The beneficial effects brought by the technical solution provided by the present invention include:

Embodiments of the present invention provide a smart card anti-side channel attack protection method and device, because the smart card anti-side channel attack protection method calculates a security policy sequence number according to a security policy sequence mark and a policy factor, and invokes an application of a smart card according to the security policy sequence number The corresponding security policy in the layer is implemented, and the corresponding security policy is implemented in the application layer. Therefore, the application layer only needs to use the security policy method to resist side-channel attacks before important processes, without adding too much security processing, which greatly reduces the difficulty of adding security processing at the application layer and reduces the difficulty of application development and debugging.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

1 is a schematic structural diagram of a smart card anti-side channel attack protection device according to an embodiment of the present invention;

FIG. 2 is a flowchart of steps of a first smart card anti-side channel attack protection method provided by an embodiment of the present invention;

3 is a flowchart of steps of a second smart card anti-side channel attack protection method provided by an embodiment of the present invention;

FIG. 4 is a flowchart of steps of executing a corresponding security policy at an application layer in a method for protecting against side channel attacks on a smart card provided by an embodiment of the present invention;

FIG. 5 is a flowchart of steps of a third smart card anti-side channel attack protection method provided by an embodiment of the present invention.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

The embodiments of the present invention provide a smart card anti-side channel attack protection method and device, which can solve the inconsistency of implementation of different chip layers or COS layers, and it is difficult to ensure that all key processes can meet the security requirements, so it is necessary to add new security However, if too much security processing is added, it will increase the difficulty of application development and debugging.

Referring to FIG. 2, a method for protecting a smart card against side channel attacks provided by an embodiment of the present invention may include the following steps:

S201: Calculate the security policy sequence number according to the security policy sequence mark and the policy factor.

Referring to FIG. 3 and FIG. 5 , in some embodiments, before S201, it is possible to check whether the smart card is under attack through the program counter, add 1 to the last input value of the program counter, and compare it with the internally stored value, if If it is inconsistent, the verification fails, indicating that there is an external attack, record the number of attacks, and the smart card enters an abnormal state to lock. It can be used as the value of the security policy sequence tag, and the security policy sequence number obtained after the security policy sequence tag and the policy factor are calculated are also random.

In some embodiments, the calculation of the security policy sequence number according to the security policy sequence mark and the policy factor may specifically include: the value of the policy factor is denoted as β, β may be an integer greater than 0, and the security policy sequence mark may be composed of multiple bytes Composition, each byte can be a random number generated before the application layer process, each byte can be calculated by taking the remainder of β to obtain a security policy serial number to call the security policy, the security policy serial number is denoted as x, according to the calculation of the remainder The formula can know that the value range of x is from 0 to β-1. Since the bytes marked by the security policy sequence are random numbers obtained randomly, the value x obtained by the bytes calculated by taking the remainder of the policy factor β is also random. The smart card issuer can control the value range of the security policy serial number value x by setting β, which can further increase the diversity of configuration security policies. By setting different numbers of bytes, different security policies can be flexibly configured. When the smart card does not need a strong ability to resist side channel attacks, a small number of bytes can be set to invoke the security policy to resist side channel attacks without increasing It is difficult to develop and debug the application layer. When the smart card needs a strong ability to resist side channel attacks, you can increase the number of security policies to be invoked by increasing the number of bytes, so as to strengthen the ability of the smart card to resist side channel attacks.

S202: Invoke the corresponding security policy in the application layer security policy according to the security policy sequence number.

In some embodiments, the security policy includes one or more, and before invoking the corresponding security policy in the application layer of the smart card according to the security policy sequence number, it may include: pressing one or more of the security policies according to Numbering is performed in sequence, and the security policies can have α types. All types of security policies are numbered from 1 to α. After the security policies are numbered, it is convenient to call the security policies according to the numbers to resist side channel attacks.

In some embodiments, the security policies include one or more types, that is, α is 1 or greater than 1, each of the security policies corresponds to a number, and the application of the smart card is invoked according to the security policy sequence number. The corresponding security policy in the layer may include: when the calculated security policy serial number is a number between 1 and α, calling the security policy with the same number and security policy serial number to resist side channel attacks. When the security policy serial number is greater than α, there is no corresponding security policy to call. This calling method is simple and can call the security policy one by one. The calculated security policy serial number may or may not call the security policy. The security policy can be called, which increases the diversity of security policy configuration schemes. In this embodiment, the security policy sequence mark can be calculated by taking the remainder of the policy factor to obtain the security policy serial number to call the security policy. The value of the policy factor can be β, and β is For an integer greater than 0, according to the calculation formula of the remainder, the value range of the security policy serial number can be known from 0 to β-1. The smart card issuer can control the value range of the security policy serial number by setting β. When the value of β When it is greater than α, the security policy serial number can be a number from 1 to α, then a security policy with the corresponding number from 1 to α can be called, and the security policy serial number can also be greater than α and less than or equal to β-1 or If the number is equal to 0, there is no corresponding security policy that can be invoked. The larger the value of β is, the smaller the probability that the security policy sequence mark can invoke the corresponding security policy after calculating the remainder of the policy factor; when the value of β When it is less than or equal to α, the security policy sequence number can be 0, then there is no corresponding security policy to call. A security policy corresponding to the number, the smaller the value of β is set, the fewer types of corresponding security policies can be called after the byte is calculated by taking the remainder. The smart card issuer can control the calling security by setting the value of the policy factor. The number of types of policies or the probability of invoking a security policy.

S203: Execute the security policy at the application layer.

Referring to FIG. 4 , in some embodiments, the security policy includes one or more types, and executing the corresponding security policy at the application layer may include: step S301 , determining the corresponding security policy according to the security policy enable flag Whether the security policy is enabled, if so, execute the corresponding security policy. When the security policy sequence mark includes multiple bytes, each byte calculates the policy factor to obtain a security policy sequence number. If the security policy sequence number does not have a corresponding security policy sequence number If the security policy can be invoked, continue to search for the next byte. If the security policy serial number has a corresponding security policy that can be invoked, then judge whether the corresponding security policy is enabled according to the security policy enable flag, and if it is enabled, execute the corresponding security policy. If the security policy is not enabled, the corresponding security policy will not be executed, and the next byte will continue to be searched until all bytes are executed; the security policy enable flag may include at least one bit, and the number of bits may be the same as the The number of security policies is the same, each bit can correspond to a security policy, and each bit can be numbered from 1. When the bit is 1, it means that the corresponding security policy is in the open state, and the corresponding security policy can be called after being called. Execute, when the bit is 0, it means that the corresponding security policy is in a closed state, and the corresponding security policy cannot be executed after being invoked. You can control whether to execute the invoked security policy by setting the bit. It is set by the smart card issuer under certain conditions, so that it is convenient to choose a flexible security configuration scheme according to the actual situation. This method increases the diversity of protection strategies.

Referring to FIG. 4 , in some embodiments, after step S301, step S302 may be further included to execute the called security policy according to a security policy input factor, and the value of the security policy input factor is generated before the application layer process. The random number can be generated by a random number generator. The value of the security policy input factor can be the same as or different from the value marked in the security policy sequence. The security policy input factor can increase the diversity of security policy execution. To further increase the anti-attack capability of the smart card, after executing all the called security policies, the next program counter can be generated, saved and returned.

In some embodiments, the security policy includes one or more of increasing a random delay, increasing an algorithm operation, performing a write operation to a specific address, or increasing a specific data operation according to an input factor of the security policy, wherein the The security policy input factor is a random number; specifically, the security policy includes:

1) Add random delay at the application layer

A random delay can be introduced at the application layer, so that the encryption operation does not occur at the same time point of multiple power consumption waveforms, which increases the difficulty of the alignment operation, which in turn increases the difficulty of side channel attacks. The length of the random delay can be The length of the security policy input factor.

2) The application layer adds algorithm operations

An algorithm operation can be added at the application layer. The algorithm can be a symmetric algorithm or a digest algorithm, such as DES, 3DES, SM1, SM3, SM4, SHA1, SHA256, etc., where DES is a block encrypted with a key Algorithm, 3DES is a general term for triple data encryption algorithm block cipher, SM1, SM3, SM4 is a national secret algorithm issued by the National Cryptography Administration, SHA1, SHA256 are planned by the US National Security Agency, and by the US National Standards and Skills The algorithm released by the research institute, the key and data used by the above algorithm can be calculated according to the security policy input factor.

3) The application layer writes to a specific address

A write operation can be performed to a specific address at the application layer, and the written data and length can be calculated according to the security policy input factor.

4) The application layer adds specific data operations

A specific data copy or data comparison operation can be added at the application layer, and the data length and content can be calculated according to the security policy input factor.

Referring to FIG. 3 and FIG. 5 , in some embodiments, after the application layer executes the corresponding security policy, that is, after step S2 is executed, step S3 may be included to execute an application process, and the application process may be PIN verification, After the verification is completed, the verification result is saved, and the step S4 may also include selecting the execution order and the number of the current security policy according to the random number obtained at the beginning of the application process as the security policy sequence mark and the security policy input factor, for use in Resist side-channel attacks, and finally return the verification result. By hiding important processes among various random security policies, the ability of smart cards to resist side-channel attacks is enhanced.

Referring to FIG. 1 , a smart card anti-side-channel attack protection device provided by an embodiment of the present invention may include a computing module, a calling module and an execution module. The detailed description of each module is as follows: The policy sequence mark and the policy factor calculate the security policy sequence number; the calling module is used for calling the corresponding security policy in the application layer of the smart card according to the security policy sequence number; the execution module is used for executing the corresponding security policy at the application layer .

The smart card anti-side-channel attack protection device is used to implement a security control center at the application layer, uniformly configure and manage the security policy of the application layer, and the security processing of the application layer is carried out in the security control center. The side-channel attack protection device invokes security policies to resist side-channel attacks. By hiding important processes among various random security policies, it enhances the ability of smart cards to resist side-channel attacks, and greatly reduces the difficulty of increasing security processing at the application layer. Reduces the difficulty of application development and debugging.

Referring to FIG. 1 , in some embodiments, the smart card anti-side channel attack protection device further includes an acquisition module, which is configured to acquire the security policy sequence mark, wherein the security policy sequence mark is a random number, and The security policy input factor can be obtained, and its security input factor is also a random number. The random number can be generated by a random number generator. The security policy sequence mark and the security policy input factor can be the same random number or different random numbers. The random number method makes the invoked security policy random, which further increases the ability of the smart card to resist side-channel attacks. There is no need to add too many security policies to resist side-channel attacks, which reduces the difficulty of application development and debugging.

In some embodiments, embodiments of the present invention also provide a computer device, which may include a processor and a memory, and the memory may store a piece of program code or multiple pieces of program code, and the program code is loaded and executed by the processor to achieve the following: The above-mentioned smart card anti-side channel attack protection method.

In some embodiments, embodiments of the present invention further provide a computer-readable storage medium, where one piece of program code or multiple pieces of program code may be stored in the computer-readable storage medium, and the program code is loaded and executed by a processor to achieve the following: The above-mentioned smart card anti-side channel attack protection method.

The principles of a smart card anti-side channel attack protection method and device provided by the embodiments of the present invention are as follows:

Because the smart card anti-side channel attack protection method is to calculate the security policy sequence number by taking the remainder of the policy factor according to the security policy sequence mark, and then calling the corresponding security policy in the application layer of the smart card according to the security policy sequence number, and executing the corresponding security policy at the application layer. Policies are used to resist side channel attacks. The smart card anti-side channel attack protection device implements a security control center at the application layer to uniformly configure and manage application layer security policies. It is used to invoke application layer security policies before and after the application layer process to resist side channel attack. Therefore, the application layer only needs to call the smart card anti-side-channel attack protection device before and after important processes to resist side-channel attacks. It reduces the difficulty of adding security processing at the application layer, and reduces the difficulty of application development and debugging.

In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, It is not intended to indicate or imply that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as limiting the invention. Unless otherwise expressly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection, It can also be an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or an internal connection between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

It should be noted that, in the present invention, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and are not necessarily required or implied Any such actual relationship or sequence exists between these entities or operations. Moreover, the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device that includes a list of elements includes not only those elements, but also includes not explicitly listed or other elements inherent to such a process, method, article or apparatus. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in a process, method, article or apparatus that includes the element.

The above descriptions are only specific embodiments of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

A method for protecting a smart card against side channel attacks, comprising the following steps:

Calculate the security policy serial number according to the security policy sequence mark and the policy factor;

Invoke the corresponding security policy in the application layer of the smart card according to the security policy serial number;

The corresponding security policy is executed at the application layer.
The method for protecting a smart card against side-channel attacks according to claim 1, wherein before calculating the security policy sequence number according to the security policy sequence mark and the policy factor, the method further comprises:

Obtain the security policy sequence tag, where the security policy sequence tag is a random number.
The method for protecting a smart card against side-channel attacks according to claim 1, wherein the security policies include one or more types, each of the security policies has a corresponding number, and the security policies have a serial number according to the security policy. Invoke the corresponding security policy in the application layer of the smart card, including:

When the security policy serial number is the same as the security policy number, the security policy corresponding to the number is invoked.
The method for protecting a smart card against side-channel attacks according to claim 1, wherein the calculating the security policy sequence number according to the security policy sequence mark and the policy factor comprises:

Taking the remainder of the security policy sequence mark to the policy factor to obtain the security policy sequence number;

The security policy sequence mark includes at least one byte, and each byte takes the remainder of the policy factor to obtain the security policy sequence number, and the policy factor is a preset positive integer.
The method for protecting a smart card against side channel attacks according to claim 1, wherein the security policy includes one or more types, and the execution of the corresponding security policy at the application layer includes:

Determine whether the corresponding security policy is enabled according to the security policy enable flag, and if so, execute the corresponding security policy;

Wherein, the security policy enable flag includes at least one bit, each bit corresponds to one of the security policies, when the bit is 1, the corresponding security policy is in an open state; when the bit is When it is 0, the corresponding security policy is in a closed state.
The smart card anti-side channel attack protection method of claim 1, wherein:

The security policy includes, according to the security policy input factor, one or more of increasing random delay, increasing algorithm operation, performing a write operation to a specific address, or adding a specific data operation, wherein the security policy input factor is random. number.
The method for protecting a smart card against side-channel attacks according to claim 1, wherein after the application layer executes the corresponding security policy, the method further comprises:

Execute the application process;

Execute the smart card anti-side channel attack protection method according to any one of claims 1 to 7 again.
A smart card anti-side channel attack protection device, characterized in that it includes:

a calculation module, which is used to calculate the security policy sequence number according to the security policy sequence mark and the policy factor;

a calling module, which is used to call the corresponding security policy in the application layer of the smart card according to the security policy sequence number;

an execution module, which is used for executing the corresponding security policy at the application layer.
A computer device, characterized in that, the computer device includes a processor and a memory, and the memory stores at least one piece of program code, the program code is loaded and executed by the processor to implement claims 1 to 7 The smart card anti-side channel attack protection method according to any one of the above.
A computer-readable storage medium, characterized in that the computer-readable storage medium stores at least one piece of program code, and the program code is loaded and executed by a processor to implement any one of claims 1 to 7. The above-mentioned smart card anti-side channel attack protection method.