Protection circuit, encryption chip and equipment for preventing side channel attack caused by external power supply current analysis

Abstract

The utility model discloses a protection circuit, an encryption chip and equipment for preventing side channel attack in external power supply current analysis. The protection circuit comprises a protection unit, a filtering unit and a direct current converter, wherein one end of the protection unit is connected with a power supply, and the other end of the protection unit is connected with one end of the filtering unit; the other end of the filtering unit is connected with one end of the direct current converter; the other end of the direct current converter is connected with a circuit board provided with a password module; the protection unit is used for carrying out overcurrent protection on the circuit board; the filtering unit is used for filtering the reverse radiation current generated by the circuit board; and the direct current converter is used for converting a first power supply current which is output by the power supply and passes through the protection unit and the filtering unit into a target power supply current required by the circuit board, and inputting the target power supply current into the circuit board to supply power to the circuit board. And the reliability of side channel attack prevention is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of information security, and in particular to a protection circuit, an encryption chip and a device for preventing a side channel attack by analyzing a current of an external power supply. Background Art

[0002] As the name implies, a side channel attack is a method of obtaining additional information through unconventional information channels and obtaining secret information "indirectly". It is sometimes called a bypass attack. In practical applications, the cryptographic module in the electronic device to be protected will leak its internal state information in the form of energy consumption during operation. This information related to the key used by the cryptographic algorithm is called side information. The electronic devices to be protected are, for example, smart home devices and smart robots. In the process of attacking the cryptographic module, the attacker can use a variety of side information analysis techniques to recover secret information such as keys.

[0003] In the related art, there are two main methods to prevent side channel attacks: one is to change the side channel leakage characteristics of the encryption and decryption unit in the time dimension, which is mainly achieved by changing the execution time of the operation implemented by the encryption algorithm; the other is to hide the side channel leakage characteristics of the encryption unit in the amplitude dimension, which is mainly achieved by directly making the amount of side information of the operation performed by the encryption and decryption unit equal or random. However, the above two methods to prevent side channel attacks only increase the computational difficulty of side information analysis, and the key can still be deciphered through more complex side information analysis.

[0004] Considering that the waveform of the external power supply current will change when the password module in the protection device performs key verification, there is a risk of calculating the energy consumption waveform of the password module operation based on the waveform of the external power supply current, and then analyzing and calculating the risk of stealing the key. At present, there is no more effective solution to the above risks. Therefore, the side channel attack prevention method in the related art still has the problem of poor reliability. Utility Model Content

[0005] The embodiments of the utility model provide a protection circuit, an encryption chip and a device for preventing side-channel attacks by analyzing the current of an external power supply, so as to solve the problem in the prior art that the energy consumption waveform of the cryptographic module during operation is calculated based on the waveform of the current size of the external power supply, and then the risk of stealing the key is analyzed and calculated, thus the reliability of preventing side-channel attacks is poor.

[0006] In a first aspect, an embodiment of the utility model provides a protection circuit for preventing side channel attacks by analyzing the current of an external power supply, comprising: a protection unit, a filtering unit and a DC converter; wherein:

[0007] One end of the protection unit is connected to the power supply, and the other end is connected to one end of the filter unit; the other end of the filter unit is connected to one end of the DC converter; the other end of the DC converter is connected to a circuit board with a password module deployed;

[0008] The protection unit is used to perform overcurrent protection on the circuit board;

[0009] The filtering unit is used to filter the reverse radiation current generated by the circuit board;

[0010] The DC converter is used to convert the first power supply current output by the power supply through the protection unit and the filter unit into the target power supply current required by the circuit board, and input the target power supply current into the circuit board to power the circuit board.

[0011] The embodiment of the utility model provides a protection circuit for preventing a side channel attack by analyzing an external power supply current, comprising: a protection unit, a filtering unit and a direct current converter; the power supply current output by a power supply passes through the protection unit, the filtering unit and the direct current converter to supply power to a circuit board; wherein the direct current converter converts a first power supply current output by the power supply passing through the protection unit and the filtering unit into a target power supply current required by the circuit board, and inputs the target power supply current into the circuit board to supply power to the circuit board; the protection unit in the circuit performs overcurrent protection on the circuit board; the password module generates reverse radiation when running, so that a circuit board equipped with the password module generates reverse radiated current variation ripple, that is, reverse radiation current; the filtering unit arranged in the circuit performs filtering processing on the reverse radiation current generated by the circuit board, and the current variation ripple generated by the operation of the password module can be attenuated by the filtering processing, and the current variation ripple can be prevented from radiating back to the external power supply to a certain extent, so that from the perspective of hardware design, it is avoided to infer the energy consumption waveform when the password module is operated according to the waveform of the current size of the external power supply, and then analyze and calculate the risk of stealing the key, thereby improving the reliability of preventing side channel attacks.

[0012] In an optional embodiment, it further includes: an energy storage unit; wherein:

[0013] The other end of the filter unit is connected to one end of the energy storage unit; the other end of the energy storage unit is connected to one end of the DC converter;

[0014] The energy storage unit is used to input the second power supply current into the DC converter; the DC converter converts the second power supply current into a target power supply current required by the circuit board, and inputs the target power supply current into the circuit board to power the circuit board; wherein the energy storage unit is charged by the power supply.

[0015] In the above circuit, the power supply current output by the power supply passes through the protection unit and the filter unit to supply power to the energy storage unit, and the energy storage unit supplies power to the circuit board. Specifically, the energy storage unit inputs the second power supply current into the DC converter; the DC converter converts the second power supply current into the target power supply current required by the circuit board, and inputs the target power supply current into the circuit board to supply power to the circuit board. In this way, the reverse radiation current generated by the circuit board with the password module deployed will act on the energy storage unit, but will not directly act on the power supply. It can avoid the energy consumption waveform of the password module when operating according to the waveform of the external power supply current, and then analyze and calculate the risk of stealing the key. In one case, if the energy storage unit radiates a reverse current, the filter unit set in the circuit performs a filtering process on the reverse current radiated from the energy storage unit. After filtering, the reverse current can be further attenuated, and the current change ripple can be further prevented from radiating back to the external power supply, which further avoids the energy consumption waveform of the password module when operating according to the waveform of the external power supply current from the perspective of hardware design, and then analyzes and calculates the risk of stealing the key, thereby improving the reliability of preventing side channel attacks.

[0016] In an optional embodiment, the protection unit includes: a fuse and a thyristor; wherein:

[0017] One end of the thyristor is grounded; one end of the fuse is connected to the power supply; an ungrounded end of the thyristor and an end of the fuse not connected to the power supply are connected to the filter unit.

[0018] In an optional embodiment, the filtering unit includes: a π-type low-pass filter.

[0019] π-type low-pass filters produce high impedance at high frequencies and low impedance at low frequencies. Therefore, they are used in transmission lines to block unwanted high frequencies.

[0020] In an optional embodiment, the filtering unit includes: a first capacitor, an inductor and a second capacitor; wherein:

[0021] One end of the first capacitor is grounded; one end of the second capacitor is grounded; the ungrounded end of the thyristor in the protection unit and the end of the fuse that is not connected to the power supply are connected to the ungrounded end of the first capacitor; the ungrounded end of the second capacitor is connected to the DC converter; the ungrounded end of the first capacitor is also connected to one end of the inductor; the other end of the inductor is connected to the ungrounded end of the second capacitor.

[0022] In an optional embodiment, the filtering unit includes: a first capacitor, an inductor and a second capacitor; the energy storage unit includes a diode, a resistor and a third capacitor; wherein:

[0023] One end of the first capacitor is grounded; one end of the second capacitor is grounded; the ungrounded end of the thyristor in the protection unit and the end of the fuse that is not connected to the power supply are connected to the ungrounded end of the first capacitor; the ungrounded end of the second capacitor is connected to the anode of the diode; the ungrounded end of the first capacitor is also connected to one end of the inductor; the other end of the inductor is connected to the ungrounded end of the second capacitor; the cathode of the diode is connected to one end of the resistor; one end of the third capacitor is grounded; the ungrounded end of the third capacitor and the end of the resistor that is not connected to the cathode of the diode are connected to the DC converter.

[0024] The password module will generate reverse radiation when it is running, so the circuit board with the password module will generate reverse radiated current change ripple, that is, reverse radiation current; the filter unit set in the circuit filters the reverse radiation current generated by the circuit board, and the current change ripple generated by the password module operation can be attenuated after filtering, which can prevent the current change ripple from radiating back to the external power supply to a certain extent. Specifically, the second capacitor in the filter unit attenuates the current change ripple, and the attenuated current change ripple passes through the inductor, and the inductor further attenuates the current change ripple. The further attenuated current change ripple passes through the first capacitor, and the first capacitor further attenuates the current change ripple. Thereby, it is more effective to avoid the energy consumption waveform of the password module operation based on the external power supply current size waveform from the perspective of hardware design, and then analyze and calculate the risk of stealing the key, thereby improving the reliability of preventing side channel attacks.

[0025] In an optional embodiment, the third capacitor includes electrodes, an electrolyte, a collector, an isolation membrane, a connecting pole, a sealing material and an exhaust valve.

[0026] In an optional embodiment, the DC converter includes: a DC-DC direct current-to-direct current converter.

[0027] In a second aspect, an embodiment of the utility model provides an encryption chip, including the above-mentioned protection circuit for preventing side channel attacks by analyzing the current of an external power supply.

[0028] In a third aspect, an embodiment of the utility model provides an electronic device, comprising the above-mentioned encryption chip.

[0029] For the technical effects that may be achieved by the encryption chip of the second aspect of the utility model and the electronic device of the third aspect of the utility model, please refer to the technical effects that can be achieved by the first aspect or various possible solutions in the first aspect, and no further details will be given here. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 A schematic diagram of the energy trace signal waveform and the key correspondence provided for the related technology;

[0032] Figure 2 A schematic diagram of a protection circuit for preventing side channel attacks by analyzing the current of an external power supply provided by an embodiment of the utility model;

[0033] Figure 3 A schematic diagram of a protection circuit for preventing side channel attacks by analyzing the current of an external power supply provided by an embodiment of the utility model;

[0034] Figure 4 It is a schematic diagram of a power supply scheme in the related technology;

[0035] Figure 5 A schematic diagram of a power supply scheme provided for an embodiment of the utility model;

[0036] Figure 6 A circuit diagram of the protection unit provided by the utility model;

[0037] Figure 7 A circuit diagram for preventing side channel attacks by analyzing the current of an external power supply provided by the utility model;

[0038] Figure 8 A circuit diagram for preventing side channel attacks by analyzing the current of an external power supply provided by the utility model;

[0039] Fig. 9 A schematic diagram of a supercapacitor provided by the utility model;

[0040] Fig.10 This is a schematic diagram of an equivalent model of a supercapacitor discharge circuit provided by the utility model. DETAILED DESCRIPTION

[0041] The present invention will be further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] Unless otherwise defined, the technical or scientific terms used in the present invention shall have the usual meanings understood by persons with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" and the like mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" and the like are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0043] In order to protect the user's information security, the plaintext data sent by the electronic device will be encrypted according to the key when passing through the password module to encrypt the plaintext data and form ciphertext data. However, in the process of encrypting the plaintext data, energy changes will occur. By obtaining the energy changes in the encryption process and using the energy analysis attack method, external personnel can decipher the key used by the encryption unit, thereby recovering the user information and causing the user information to be leaked.

[0044] The basic principle of side-channel attack by analyzing the external power supply current: mobile phones and other devices automatically switch to external power supply when plugged in. The change of energy consumption during key verification causes the change of input current. By obtaining the change of external power supply current, the waveform of energy consumption during key verification operation can be restored.

[0045] The basic principle of SPA (Simple Power Analysis) attack is: Pt=Po+Pd+Pe+Pc, where Pt is the total energy consumption of the electronic device; Po is the operation component in the energy trace that depends on the operation performed by the electronic device, that is, the operation-dependent component, where the energy trace is a sampled signal of the energy consumption of the electronic device; Pd is the data component in the energy trace that depends on the processing of the electronic device, that is, the data-dependent component; Pe is electronic noise that is independent of the operation and data; and Pc is a constant that is independent of the operation and data.

[0046] When performing SPA attacks, each data bit in the key corresponds to a different operation, and different operations will leak side information of the key, that is, the key can be recovered according to the operation-dependent component Po. Taking the modular exponent in the RSA algorithm as an example, in the process of calculating the modular exponent "md mod n", the modular square calculation and modular multiplication calculation depend on whether the value of the corresponding bit of the private key "d" is 0 or 1. If it is 0, the modular square calculation is performed, and if it is 1, the modular multiplication calculation is performed.

[0047] The computation time of the two computation operations is significantly different, forming two different patterns in the energy trace signal. Based on this, the values ​​of all bits of the private key can be recovered by observing the two patterns appearing in the energy trace, and thus the private key can be recovered. Figure 1 A schematic diagram of the energy trace signal waveform and the key corresponding to the related technology is provided, such as Figure 1 As shown in the figure, during the execution of modular exponentiation in the RSA algorithm, the sequential operations are "SS SM SM SSS SM SS SM SM SSS". Here, "S" represents the modular square operation, and the corresponding bit value is 0; "SM" represents the modular multiplication operation, and the corresponding bit value is 1, so the private key used by the RSA algorithm is "001100010011000".

[0048] In the related art, there are two main methods for preventing side channel attacks: one is to change the side channel leakage characteristics of the encryption and decryption unit in the time dimension, which is mainly achieved by changing the operation execution time implemented by the encryption algorithm; the other is to hide the side channel leakage characteristics of the encryption unit in the amplitude dimension, which is mainly achieved by directly making the amount of side information of the operation performed by the encryption and decryption unit equal or random. However, the above two methods for preventing side channel attacks only increase the computational difficulty of side information analysis, and the key can still be deciphered through more complex side information analysis. Considering that the waveform of the external power supply current size will change when the password module in the protection device performs key verification, there is a risk of calculating the energy consumption waveform of the password module operation based on the waveform of the external power supply current size, and then analyzing and calculating the risk of stealing the key. Therefore, the utility model provides a protection circuit, encryption chip and device for preventing side channel attacks by external power supply current analysis. It is used to solve the problem of poor reliability of the side channel attack prevention method in the related art.

[0049] The solution provided by the embodiment of the utility model is described in detail below with reference to the accompanying drawings.

[0050] Figure 2 A schematic diagram of a protection circuit for preventing a side channel attack by analyzing the current of an external power supply provided by an embodiment of the utility model includes: a protection unit 11, a filtering unit 12 and a DC converter 13; wherein:

[0051] One end of the protection unit 11 is connected to the power supply, and the other end is connected to one end of the filter unit 12; the other end of the filter unit 12 is connected to one end of the DC converter 13; the other end of the DC converter 13 is connected to a circuit board with a password module deployed;

[0052] The protection unit 11 is used to provide overcurrent protection for the circuit board;

[0053] The filtering unit 12 is used to filter the reverse radiation current generated by the circuit board;

[0054] The DC converter 13 is used to convert the first power supply current output by the power supply through the protection unit 11 and the filter unit 12 into the target power supply current required by the circuit board, and input the target power supply current into the circuit board to power the circuit board.

[0055] The embodiment of the utility model provides a protection circuit for preventing the analysis of the current of an external power supply from performing a side channel attack, comprising: a protection unit 11, a filtering unit 12 and a DC converter 13; the power supply current output by the power supply passes through the protection unit 11, the filtering unit 12 and the DC converter 13 to supply power to the circuit board. The DC converter 13 converts the first power supply current output by the power supply through the protection unit 11 and the filtering unit 12 into the target power supply current required by the circuit board, and inputs the target power supply current into the circuit board to supply power to the circuit board. The protection unit 11 in the circuit performs overcurrent protection on the circuit board; the password module generates reverse radiation when running, so that the circuit board with the password module deployed generates reverse radiation current change ripple, that is, reverse radiation current; the filtering unit 12 set in the circuit performs filtering processing on the reverse radiation current generated by the circuit board, and the current change ripple generated by the operation of the password module can be attenuated after filtering processing, and the current change ripple can be prevented from radiating back to the external power supply to a certain extent, so that from the perspective of hardware design, it is avoided to infer the energy consumption waveform of the password module operation according to the waveform of the current size of the external power supply, and then analyze and calculate the risk of stealing the key, thereby improving the reliability of preventing side channel attacks.

[0056] Figure 3 The schematic diagram of the protection circuit for preventing the external power supply current analysis from performing side channel attacks provided by the embodiment of the utility model also includes: an energy storage unit 14; wherein:

[0057] The other end of the filter unit 12 is connected to one end of the energy storage unit 14; the other end of the energy storage unit 14 is connected to one end of the DC converter 13;

[0058] The energy storage unit 14 is used to input the second power supply current into the DC converter 13; the DC converter 13 converts the second power supply current into the target power supply current required by the circuit board, and inputs the target power supply current into the circuit board to power the circuit board; wherein the energy storage unit 14 is charged by the power supply.

[0059] The power supply current output by the power supply passes through the protection unit 11 and the filter unit 12, and supplies power to the energy storage unit 14, and the energy storage unit 14 supplies power to the circuit board. Specifically, the energy storage unit 14 will output the power supply current to power the circuit board. In the embodiment of the utility model, the power supply current output by the energy storage unit 14 is referred to as the second power supply current. The energy storage unit 14 inputs the second power supply current into the DC converter 13; the DC converter 13 converts the second power supply current into the target power supply current required by the circuit board, and inputs the target power supply current into the circuit board to power the circuit board. In this way, the reverse radiation current generated by the circuit board equipped with the password module will act on the energy storage unit, but will not directly act on the power supply. It can avoid the energy consumption waveform of the password module during operation being calculated based on the waveform of the external power supply current, and then analyze and calculate the risk of stealing the key. In one case, if the energy storage unit 14 is short of power, the power supply current passes through the protection unit 11 and the filter unit 12 to supply power to the energy storage unit 14. When the energy storage unit 14 supplies power to the circuit board, a reverse current may be radiated at the energy storage unit 14. The filter unit 12 provided in the circuit performs filtering processing on the reverse current radiated from the energy storage unit 14. After filtering processing, the reverse current can be further attenuated, and the current change ripple can be further prevented from radiating back to the external power supply. This further avoids the energy consumption waveform of the cryptographic module operation based on the waveform of the external power supply current from the perspective of hardware design, and further analyzes and calculates the risk of stealing the key, thereby improving the reliability of preventing side channel attacks.

[0060] Figure 4 It is a schematic diagram of a power supply scheme in the related technology, including a power supply, a protection unit, a DC converter and a circuit board. Figure 5 A schematic diagram of a power supply scheme provided for an embodiment of the utility model includes a power supply, a protection unit, a filtering unit, an energy storage unit, a DC converter and a circuit board.

[0061] Figure 6 The circuit diagram of the protection unit provided by the utility model includes a fuse F and a thyristor D; wherein:

[0062] One end of the thyristor D is grounded; one end of the fuse F is connected to the power supply; the ungrounded end of the thyristor D and the end of the fuse F not connected to the power supply are connected to the filter unit 12.

[0063] In the above circuit, the fuse F (fuse) mainly plays an overload protection role. If the fuse F is correctly placed in the circuit, the fuse F will melt and cut off the current when the current abnormally rises to a certain height and temperature, thus protecting the safe operation of the circuit and realizing overcurrent protection for the circuit board.

[0064] The main function of thyristor D in the circuit is to achieve controlled rectification. When a positive voltage is applied between the cathode and anode of thyristor D and no signal is applied to the control electrode, thyristor D is in the off state. If a small positive voltage is applied between the control electrode and the cathode, thyristor D will be turned on. At this time, even if the control signal is removed, thyristor D can still remain turned on unless the anode power supply circuit is disconnected or the anode current is reduced to less than the holding current of thyristor D. Under normal circumstances, the current required to trigger thyristor D is equal to 1 / 100 to 1 / 1000 of the current flowing through thyristor D. When thyristor D is connected in series to the secondary winding of the arc welding transformer and the welding cable, it can not only convert AC into DC, but also control the size of the welding current with the cooperation of the corresponding electronic device. Thyristor D has only two working states, namely, on and off, and the current can only be adjusted by adjusting the conduction point (trigger angle) of thyristor D. The earlier the conduction time of thyristor D, the greater the power output to the load.

[0065] During the operation of thyristor D, its anode (A) and cathode (K) are connected to the power supply and load to form the main circuit of thyristor D. The gate G and cathode K of thyristor D are connected to the device for controlling the thyristor to form the control circuit of thyristor D. Thyristor D is a semi-controlled power electronic device. Its working conditions include: when thyristor D is subjected to reverse anode voltage, no matter what voltage the gate is subjected to, thyristor D is in reverse blocking state. When thyristor D is subjected to positive anode voltage, the thyristor is turned on only when the gate is subjected to positive voltage. At this time, thyristor D is in forward conduction state, which is the thyristor current characteristic of thyristor D, i.e., controllable characteristic. When thyristor D is turned on, as long as there is a certain positive anode voltage, no matter what the gate voltage is, thyristor D remains turned on, that is, after thyristor D is turned on, the gate loses its function. The gate only plays a triggering role. When thyristor D is turned on, when the main circuit voltage (or current) decreases to near zero, thyristor D is turned off.

[0066] In an embodiment of the utility model, the filtering unit includes: a π-type low-pass filter.

[0067] Figure 7 The circuit diagram for preventing the external power supply current analysis from performing side channel attacks provided by the utility model, the filtering unit comprises: a first capacitor C1, an inductor L and a second capacitor C2; wherein:

[0068] One end of the first capacitor C1 is grounded; one end of the second capacitor C2 is grounded; the ungrounded end of the thyristor D in the protection unit and the end of the fuse F that is not connected to the power supply are connected to the ungrounded end of the first capacitor C1; the ungrounded end of the second capacitor C2 is connected to the DC converter 13; the ungrounded end of the first capacitor C1 is also connected to one end of the inductor L; the other end of the inductor L is connected to the ungrounded end of the second capacitor C2.

[0069] The password module will generate reverse radiation when it is running, so the circuit board with the password module will generate reverse radiated current change ripple, that is, reverse radiation current; the filter unit set in the circuit filters the reverse radiation current generated by the circuit board, and the current change ripple generated by the password module operation can be attenuated after filtering, which can prevent the current change ripple from radiating back to the external power supply to a certain extent. Specifically, the second capacitor in the filter unit attenuates the current change ripple, and the attenuated current change ripple passes through the inductor, and the inductor further attenuates the current change ripple. The further attenuated current change ripple passes through the first capacitor, and the first capacitor further attenuates the current change ripple. Thereby, it is more effective to avoid the energy consumption waveform of the password module operation based on the external power supply current size waveform from the perspective of hardware design, and then analyze and calculate the risk of stealing the key, thereby improving the reliability of preventing side channel attacks.

[0070] Figure 8 The circuit diagram for preventing the external power supply current analysis from performing side channel attacks provided by the utility model, the filtering unit includes: a first capacitor C1, an inductor L and a second capacitor C2; the energy storage unit includes a diode D1, a resistor R and a third capacitor C3; wherein:

[0071] One end of the first capacitor C1 is grounded; one end of the second capacitor C2 is grounded; the ungrounded end of the thyristor D in the protection unit and the end of the fuse F not connected to the power supply are connected to the ungrounded end of the first capacitor C1; the ungrounded end of the second capacitor C2 is connected to the anode of the diode D1; the ungrounded end of the first capacitor C1 is also connected to one end of the inductor L; the other end of the inductor L is connected to the ungrounded end of the second capacitor C2; the cathode of the diode D1 is connected to one end of the resistor R; one end of the third capacitor C3 is grounded; the ungrounded end of the third capacitor C3 and the end of the resistor R not connected to the cathode of the diode D1 are connected to the DC converter 13.

[0072] The power supply current output by the power supply passes through the protection unit 11 and the filter unit 12, and supplies power to the third capacitor C3 in the energy storage unit 14, and the third capacitor C3 in the energy storage unit 14 supplies power to the circuit board. Specifically, the third capacitor C3 in the energy storage unit 14 will output a power supply current to power the circuit board. In the embodiment of the utility model, the power supply current output by the third capacitor C3 in the energy storage unit 14 is referred to as the second power supply current. The third capacitor C3 in the energy storage unit 14 inputs the second power supply current into the DC converter 13; the DC converter 13 converts the second power supply current into the target power supply current required by the circuit board, and inputs the target power supply current into the circuit board to power the circuit board. In this way, the reverse radiation current generated by the circuit board with the password module deployed will act on the energy storage unit, but will not directly act on the power supply. It can avoid the energy consumption waveform of the password module during operation being calculated based on the waveform of the external power supply current, and then analyze and calculate the risk of stealing the key. In one case, if the energy storage unit 14 is insufficiently charged, the power supply current passes through the protection unit 11 and the filter unit 12 to supply power to the energy storage unit 14. When the energy storage unit 14 supplies power to the circuit board, it is possible that a reverse current is radiated at the energy storage unit 14. The filter unit 12 provided in the circuit filters the reverse current radiated from the energy storage unit 14. The second capacitor in the filter unit attenuates the current change ripple. The attenuated current change ripple passes through the inductor. The inductor further attenuates the current change ripple. The further attenuated current change ripple passes through the first capacitor. The first capacitor further attenuates the current change ripple. The current change ripple is further prevented from radiating back to the external power supply, and from the perspective of hardware design, the energy consumption waveform during the operation of the cryptographic module is further avoided from being inferred based on the waveform of the external power supply current size, and the risk of key theft is further analyzed and calculated, thereby improving the reliability of preventing side channel attacks.

[0073] The π-type filter used in the utility model is an excellent low-pass filter. The π filter circuit is composed of two sets of capacitors connected in parallel and one inductor connected in series to form a π shape. Each set of capacitors includes one capacitor or multiple capacitors. The π filter circuit is described by taking the first capacitor C1, the inductor L and the second capacitor C2 as an example.

[0074] The construction and component values ​​of the π filter calculation can be derived from the following equations:

[0075] Cut-off frequency (fc) = 1 / л(LC)1 / 2;

[0076] Capacitance value is (C) = 1 / Z0лf c ;

[0077] Inductance (L1) = Z0 / лf c ;

[0078] Where Z0 is the impedance characteristic in ohms, f c is the cutoff frequency.

[0079] Configured as a low-pass filter for DC filtering purposes, the π filter is a highly efficient filter that filters out unwanted current variation ripples from the load end. Changes in load power consumption will cause changes in the input current, which will form reverse radiation to the input, forming current variation ripples at the input. Due to the effects of capacitance and reactance, capacitors provide low impedance in AC but high resistance in DC. Due to the low impedance of the π filter to AC (current variation ripples) at both ends, the current variation ripples that are reversely radiated from the load end to the π filter C2 capacitor and continue to reversely radiate enter the inductor L. Inductor L further attenuates the current variation ripple, and the remaining current variation ripples that pass through the inductor L will be further attenuated through the C1 capacitor. These multi-stage filtering helps to prevent the reverse current variation ripples generated on the π filter from being reversely radiated to the external power input port.

[0080] In an embodiment of the utility model, the third capacitor includes electrodes, an electrolyte, a collector, an isolation membrane, a connecting pole, a sealing material and an exhaust valve.

[0081] In the above circuit, the third capacitor in the energy storage unit can be a supercapacitor. Supercapacitors have high power, fast charging speed, large discharge current, long service life, and no pollution to the environment. It has great development prospects. The single voltage of supercapacitors is not high, generally only 1V-4V. In practical applications, supercapacitors are usually used in series and parallel as needed. Supercapacitors are mainly composed of electrodes, electrolytes, collectors, isolation membranes, connecting poles, sealing materials and exhaust valves. The material and manufacturing technology of the electrodes, the composition of the electrolyte and the quality of the isolation membrane have a great influence on the performance of supercapacitors. The decomposition voltage of the electrolyte determines the working voltage of the capacitor, and the working voltage determines the energy and output power of the capacitor. Generally, the decomposition voltage of aqueous electrolytes is about 1V, and that of organic electrolytes is about 3V; the materials of electrodes and electrolytes usually determine the working principle of supercapacitors.

[0082] In addition, the utility model adopts supercapacitor as the device of energy storage unit. The energy storage unit supplies power to the circuit board, and the external power supply supplies power to the energy storage unit. In this way, the instantaneous power consumption generated during key calculation is directly supplied by the energy storage unit, and the external power supply then replenishes the charge to the energy storage unit, which does not directly cause the current fluctuation of the external power supply. Fig. 9 A schematic diagram of a supercapacitor provided by the utility model.

[0083] Supercapacitors are mainly divided into three categories according to their energy storage mechanism: (1) double-layer capacitors generated by charge separation at the interface between carbon electrodes and electrolytes; (2) faradaic capacitors that use metal oxides as electrodes and undergo redox reactions on the electrode surface and in the bulk to produce reversible chemical adsorption; and (3) capacitors that use conductive polymers as electrodes and undergo redox reactions. Since the charging and discharging of double-layer capacitors is a purely physical process, they have a high number of cycles and a fast charging process, but they store less energy. To meet the large capacity requirements of hybrid vehicles, double-layer capacitors and faradaic capacitors are usually combined to form hybrid supercapacitors with asymmetric electrodes.

[0084] The voltage u, current i, charge Q and capacity W of the supercapacitor satisfy the following relationship:

[0085]

[0086] Q = i × dt = c × du;

[0087]

[0088] If there are differences in capacitance between capacitors, the rate of change of voltage will be different under constant current charging conditions. The smaller the capacitance, the faster the voltage rises. The capacitance of a capacitor is proportional to the square of the voltage, so the difference in capacitance will result in different capacitance of each capacitor during the charging process.

[0089] The discharge process of a supercapacitor is the reverse process of charging. Its discharge characteristics are similar to the output characteristics of a traditional capacitor. When an external load is connected, the voltage changes exponentially. Since the load equivalent resistance is usually smaller than the internal parallel equivalent resistance REP of the supercapacitor, the role of REP can be ignored when analyzing the discharge process of the supercapacitor, and it can be equivalent to an ideal capacitor C. f Circuit model in series with series equivalent impedance Res. Fig.10 This is a schematic diagram of an equivalent model of a supercapacitor discharge circuit provided by the utility model.

[0090] During the discharge process, the relationship between the voltage U(t) across the supercapacitor and the discharge current I(t) is:

[0091] U(t)=U c (t)-I(t)×Res;

[0092] As can be seen from the formula, the change in the voltage value across the supercapacitor is closely related to the voltage across the ideal capacitor and the discharge current. When discharging with a small current, the voltage drop on Res can be ignored. At this time, the supercapacitor can be equivalent to an ideal capacitor, and energy storage analysis can be performed according to the relevant formula of the ideal capacitor. When discharging with a large current, the voltage drop on Res is large. If the negative electrode voltage U(t) is detected to reach the specified lower limit, the supercapacitor will stop operating. From the formula, it can be seen that at this time, the voltage Uc(t) across the ideal capacitor still remains at a large value, that is, the energy stored in the supercapacitor is not completely released. It can be seen that the existence of the series equivalent resistance Res affects the power output of the supercapacitor and reduces the effective energy storage of the supercapacitor. Therefore, when discharging with a large current, the energy consumption of Res cannot be ignored. In the process of supercapacitor discharge, it is inevitable that the terminal voltage will drop. In order to meet the load demand and improve the utilization rate of energy storage, it is usually necessary to configure a power electronic converter for the supercapacitor. By adjusting the power converter, the supercapacitor is in a constant current discharge, constant voltage discharge, or constant power discharge mode. Among them, constant voltage discharge is the most commonly used method in practical applications.

[0093] The DC converter includes a DC-DC converter.

[0094] The DC-DC converter can convert any DC voltage into the required DC voltage.

[0095] The utility model adds an energy storage unit and a filter unit to the external power input end of a hardware device such as a robot to prevent the change in energy consumption during key verification from causing the change in the input external power current. By obtaining the change in the external power current, the waveform of energy consumption during key verification calculation is restored, thereby analyzing and calculating the key. The energy consumption waveform during key verification is avoided directly from the source, directly eliminating the possibility of obtaining the key by analyzing the external power current, and it does not increase the key verification time and does not affect the user experience.

[0096] The utility model combines a π-type filter with a supercapacitor, wherein the supercapacitor supplies power to the circuit board, and the external power supply supplies power to the supercapacitor, and then further filters the power through the π-type filter, thereby ensuring that the current change at the power supply input port cannot obtain the change waveform caused by the key operation. The utility model does not change the key information encoding algorithm, and does not increase the calculation time cost. It can also improve the electromagnetic compatibility (EMC) performance of electronic equipment.

[0097] The utility model provides a hardware design for preventing side channel attacks by analyzing the current of an external power supply, and is used to prevent the change of the external power supply current when obtaining the key verification of intelligent hardware products such as robots, and then analyzing and calculating the key. The utility model adds an energy storage unit and a filter unit to the external power supply input end of hardware devices such as robots to prevent the change of input current caused by the change of energy consumption during key verification, and restores the waveform of energy consumption during key verification operation by obtaining the change of the external power supply current, and then calculates the flip of the secret key '1' through the change of the waveform to obtain the key.

[0098] Based on the same concept, the embodiment of the utility model also provides an encryption chip, including a protection circuit for preventing side channel attacks by analyzing the external power supply current as provided in any of the above embodiments. The principle of solving the problem by the encryption chip is similar to that of the protection circuit for preventing side channel attacks by analyzing the external power supply current, so the implementation of the encryption chip can refer to the implementation of the protection circuit for preventing side channel attacks by analyzing the external power supply current, and the repeated parts will not be repeated.

[0099] Based on the same concept, the embodiment of the utility model also provides an electronic device, including the encryption chip provided in the above embodiment. The principle of solving the problem by the electronic device is similar to that of the above encryption chip, so the implementation of the electronic device can refer to the implementation of the above encryption chip, and the repeated parts will not be repeated.

[0100] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0101] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A protection circuit for preventing side channel attacks by analyzing the current of an external power supply, characterized in that: include: Protection unit, filter unit and DC converter; wherein: One end of the protection unit is connected to the power supply, and the other end is connected to one end of the filter unit; the other end of the filter unit is connected to one end of the DC converter; the other end of the DC converter is connected to a circuit board with a password module deployed; The protection unit is used to perform overcurrent protection on the circuit board; The filtering unit is used to filter the reverse radiation current generated by the circuit board; The DC converter is used to convert the first power supply current output by the power supply through the protection unit and the filter unit into the target power supply current required by the circuit board, and input the target power supply current into the circuit board to power the circuit board.

2. The circuit according to claim 1, characterized in that Also includes: Energy storage unit; wherein: The other end of the filter unit is connected to one end of the energy storage unit; the other end of the energy storage unit is connected to one end of the DC converter; The energy storage unit is used to input the second power supply current into the DC converter; the DC converter converts the second power supply current into a target power supply current required by the circuit board, and inputs the target power supply current into the circuit board to power the circuit board; wherein the energy storage unit is charged by the power supply.

3. The circuit according to claim 2, characterized in that The protection unit comprises: a fuse and a thyristor; wherein: One end of the thyristor is grounded; one end of the fuse is connected to the power supply; an ungrounded end of the thyristor and an end of the fuse not connected to the power supply are connected to the filter unit.

4. The circuit according to claim 3, characterized in that The filtering unit comprises: a π-type low-pass filter.

5. The circuit according to claim 4, characterized in that The filtering unit comprises: a first capacitor, an inductor and a second capacitor; wherein: One end of the first capacitor is grounded; one end of the second capacitor is grounded; the ungrounded end of the thyristor in the protection unit and the end of the fuse that is not connected to the power supply are connected to the ungrounded end of the first capacitor; the ungrounded end of the second capacitor is connected to the DC converter; the ungrounded end of the first capacitor is also connected to one end of the inductor; the other end of the inductor is connected to the ungrounded end of the second capacitor.

6. The circuit according to claim 4, characterized in that The filtering unit includes: a first capacitor, an inductor and a second capacitor; the energy storage unit includes a diode, a resistor and a third capacitor; wherein: One end of the first capacitor is grounded; one end of the second capacitor is grounded; the ungrounded end of the thyristor in the protection unit and the end of the fuse that is not connected to the power supply are connected to the ungrounded end of the first capacitor; the ungrounded end of the second capacitor is connected to the anode of the diode; the ungrounded end of the first capacitor is also connected to one end of the inductor; the other end of the inductor is connected to the ungrounded end of the second capacitor; the cathode of the diode is connected to one end of the resistor; one end of the third capacitor is grounded; the ungrounded end of the third capacitor and the end of the resistor that is not connected to the cathode of the diode are connected to the DC converter.

7. The circuit according to claim 6, characterized in that The third capacitor includes electrodes, electrolyte, collector, isolation film, connecting pole, sealing material and exhaust valve.

8. The circuit according to claim 1, characterized in that The DC converter includes a DC-DC converter.

9. An encryption chip, characterized in that: It comprises a protection circuit for preventing side channel attacks by analyzing the current of an external power supply as described in any one of claims 1 to 8.

10. An electronic device, characterized in that: Comprising the encryption chip as described in claim 9.

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