Protection circuits, encryption chips and devices against side-channel attacks from charge and discharge recording analysis

Abstract

The utility model discloses a protection circuit, an encryption chip and a device for preventing side channel attacks by charging and discharging recording analysis, including: a sound collection unit, a filtering unit and a signal transmission unit; the sound collection unit is connected to the filtering unit, and the filtering unit is also connected to the signal transmission unit. When the password module in the protection device performs key verification, the change in energy consumption will cause the charging and discharging of the capacitor, and the charging and discharging of the capacitor will make a sound. The sound collection unit can collect the sound signal generated by the charging and discharging of the capacitor, and then convert the sound signal into a first electrical signal, and transmit the first electrical signal to the filtering unit. The filtering unit performs filtering processing on the first electrical signal to obtain a second electrical signal, and then transmits the second electrical signal to the signal transmission unit. Then, the signal transmission unit compresses the second electrical signal to obtain a third electrical signal, and transmits the third electrical signal to the electrical signal analysis device. The reliability of preventing side channel attacks 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 side channel attacks by charge and discharge recording analysis. 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 when the cryptographic module in the protection device performs key verification, the change in energy consumption will cause the capacitor to charge and discharge, and the charging and discharging of the capacitor will make a sound, the sound waves of the capacitor charging and discharging can be obtained through recording analysis, and there is a risk of calculating the key based on the sound waves of the capacitor charging and discharging. At present, there is no more effective solution to the above risks, so the side channel attack prevention method in the related technology 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 through charge and discharge recording analysis, so as to solve the risk of calculating keys based on the sound waves of capacitor charging and discharging in the prior art. Therefore, the side-channel attack prevention method still has the problem of poor reliability.

[0006] In a first aspect, an embodiment of the utility model provides a protection circuit for preventing side channel attacks by charge and discharge recording analysis, comprising: a sound collection unit, a filtering unit and a signal transmission unit; the filtering unit is connected to the sound collection unit and the signal transmission unit respectively; wherein:

[0007] The sound collection unit is used to collect the sound signal generated by the charging and discharging of the capacitor, convert the sound signal into a first electrical signal, and transmit the first electrical signal to the filtering unit;

[0008] The filtering unit is used to filter the first electrical signal to obtain a second electrical signal, and transmit the second electrical signal to the signal transmission unit;

[0009] The signal transmission unit is used to compress the second electrical signal to obtain a third electrical signal, and transmit the third electrical signal to the electrical signal analysis device.

[0010] The embodiment of the utility model provides a protection circuit for preventing side channel attacks by charging and discharging recording analysis, including: a sound collection unit, a filtering unit and a signal transmission unit; the sound collection unit is connected to the filtering unit, and the filtering unit is also connected to the signal transmission unit. When the password module in the protection device performs key verification, the change in energy consumption will cause the charging and discharging of the capacitor, and the charging and discharging of the capacitor will emit sound. The sound collection unit can collect the sound signal generated by the charging and discharging of the capacitor, and then convert the sound signal into a first electrical signal, and transmit the first electrical signal to the filtering unit. Optionally, the sound collection unit includes a MIC sound collector. The filtering unit performs filtering processing on the first electrical signal to obtain a second electrical signal, and then transmits the second electrical signal to the signal transmission unit. Since the first electrical signal directly generated by the charging and discharging sound of the capacitor is filtered by the filtering unit, the problem of the risk of calculating the key based on the sound wave of the charging and discharging of the capacitor is avoided by recording analysis. Then the signal transmission unit compresses the second electrical signal to obtain a third electrical signal, and transmits the third electrical signal to the electrical signal analysis device. Since the electrical signal acquired by the electrical signal analysis equipment is an electrical signal that has been filtered and compressed based on the first electrical signal directly generated by the sound of capacitor charging and discharging, the electrical signal that can be inferred based on the third electrical signal is also the filtered signal. The original first electrical signal directly generated by the sound of capacitor charging and discharging before filtering cannot be inferred. This solves the problem of inferring the key based on the sound waves of capacitor charging and discharging, and improves the reliability of preventing side channel attacks.

[0011] In an optional embodiment, it further includes: a signal amplification unit; wherein:

[0012] The signal amplifying unit is connected to the filtering unit and the signal transmitting unit respectively;

[0013] The filtering unit is used to filter the first electrical signal to obtain a second electrical signal, and transmit the second electrical signal to the signal amplifying unit;

[0014] The signal amplifying unit is used to perform amplitude amplification processing on the second electrical signal, and transmit the second electrical signal after the amplitude amplification processing to the signal transmission unit.

[0015] In an optional embodiment, it further includes: an ADC sampling unit; wherein:

[0016] The ADC sampling unit is connected to the signal amplifying unit and the signal transmitting unit respectively;

[0017] The signal amplifying unit is used to perform amplitude amplification processing on the second electrical signal, and transmit the second electrical signal after the amplitude amplification processing to the ADC sampling unit;

[0018] The ADC sampling unit is used to sample the second electrical signal after the amplitude amplification processing, and transmit the electrical signal obtained by the sampling processing to the signal transmission unit.

[0019] In an optional embodiment, the filtering unit includes: a Butterworth filter.

[0020] In an optional embodiment, the filtering unit includes: a first resistor, a second resistor, a first capacitor, a second capacitor, a first operational amplifier, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a third capacitor, a fourth capacitor, a second operational amplifier, a seventh resistor and an eighth resistor;

[0021] One end of the first resistor is connected to the sound collection unit; the other end of the first resistor is respectively connected to one end of the second resistor and one end of the first capacitor; the other end of the second resistor is respectively connected to one end of the second capacitor and the positive input pin of the first operational amplifier; the other end of the second capacitor is grounded; one end of the third resistor is grounded, and the other end is respectively connected to one end of the fourth resistor and the negative input pin of the first operational amplifier; the other end of the fourth resistor is respectively connected to the output pin of the first operational amplifier, one end of the fifth resistor, and one end of the first capacitor that is not connected to the first resistor; the positive power supply pin of the first operational amplifier is connected to the positive power supply, and the negative power supply pin of the first operational amplifier is connected to the negative power supply;

[0022] One end of the fifth resistor that is not connected to the fourth resistor is respectively connected to one end of the sixth resistor and one end of the third capacitor; the other end of the sixth resistor is respectively connected to one end of the fourth capacitor and the positive input pin of the second operational amplifier; the other end of the fourth capacitor is grounded; one end of the seventh resistor is grounded, and the other end is respectively connected to one end of the eighth resistor and the negative input pin of the second operational amplifier; the other end of the eighth resistor is respectively connected to the output pin of the second operational amplifier and one end of the third capacitor that is not connected to the fifth resistor; the positive power supply pin of the second operational amplifier is connected to the positive power supply, and the negative power supply pin of the first operational amplifier is connected to the negative power supply.

[0023] In an optional embodiment, the signal amplification unit includes: an LM324 amplifier.

[0024] In an optional embodiment, it further includes: an oscilloscope for testing the frequency filtering transient characteristics of the filtering unit; wherein:

[0025] One end of the first resistor connected to the sound collection unit is connected to the A channel pin of the oscilloscope; and the output end of the second operational amplifier is connected to the B channel pin of the oscilloscope.

[0026] In an optional embodiment, it further comprises: a baud meter for testing the frequency characteristics of the filtering unit; wherein:

[0027] One end of the first resistor connected to the sound collection unit is connected to the signal input pin of the baud meter; and the output end of the second operational amplifier is connected to the signal output pin of the baud meter.

[0028] 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 charge and discharge recording analysis.

[0029] In a third aspect, an embodiment of the utility model provides an electronic device, comprising the above-mentioned encryption chip.

[0030] 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

[0031] 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.

[0032] Figure 1 A schematic diagram of the energy trace signal waveform and the key correspondence provided for the related technology;

[0033] Figure 2 A schematic diagram of a protection circuit for preventing side channel attacks by charge and discharge recording analysis provided by the utility model;

[0034] Figure 3 A schematic diagram of a protection circuit for preventing side channel attacks by charge and discharge recording analysis provided by the utility model;

[0035] Figure 4 A schematic diagram of the pin connections of the LM324 amplifier provided by the utility model;

[0036] Figure 5 A schematic diagram of a protection circuit for preventing side channel attacks by charge and discharge recording analysis provided by the utility model;

[0037] Figure 6 Schematic diagram of amplitude-frequency characteristics of the second-order, fourth-order, and eighth-order Butterworth low-pass filters provided by the utility model;

[0038] Figure 7 A circuit diagram of a filter unit provided by the utility model;

[0039] Figure 8 A schematic diagram of a protection circuit for preventing side channel attacks by charge and discharge recording analysis provided by the utility model;

[0040] Fig. 9 This is a schematic diagram of the observation results of the oscilloscope when the frequency fi=1KHZ and the voltage Vi=2.5V provided by the utility model;

[0041] Fig.10 This is a schematic diagram of the observation results of the oscilloscope when the frequency fi is 20KHZ and the voltage Vi is 2.5V provided by the utility model;

[0042] Fig.11 This is a schematic diagram of the observation results of the oscilloscope when the frequency fi is 50KHZ and the voltage Vi is 2.5V provided by the utility model;

[0043] Fig.12 A schematic diagram of a protection circuit for preventing side channel attacks by charge and discharge recording analysis provided by the utility model;

[0044] Fig.13 A schematic diagram of the analysis results of the amplitude-frequency characteristics of the first baud meter provided by the utility model;

[0045] Fig.14 A schematic diagram of the analysis results of the amplitude-frequency characteristics of the second baud meter provided by the utility model;

[0046] Fig.15 A schematic diagram of the analysis results of the amplitude-frequency characteristics of the third baud meter provided by the utility model;

[0047] Fig.16 This is a schematic diagram of the analysis results of the amplitude-frequency characteristics of the fourth baud meter provided by the utility model. DETAILED DESCRIPTION

[0048] 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.

[0049] 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.

[0050] 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.

[0051] The basic principle of side-channel attack through charge and discharge recording analysis: When hardware devices verify the key, the change in energy consumption will cause the capacitor to charge and discharge. The charging and discharging of the capacitor will make a sound that is inaudible to the human ear. Sound collection devices such as MIC can record the sound of the capacitor charging and discharging. The sound waves of the recording file can be used to restore the energy consumption waveform during key verification, and then the key can be calculated.

[0052] 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.

[0053] 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.

[0054] 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".

[0055] 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 when the password module in the protection device performs key verification, the change in energy consumption will cause the charging and discharging of the capacitor, and the charging and discharging of the capacitor will make a sound, the sound waves of the charging and discharging of the capacitor can be obtained through recording analysis, and there is a risk of calculating the key based on the sound waves of the charging and discharging of the capacitor. Therefore, the utility model provides a protection circuit, encryption chip and equipment for side channel attacks by charging and discharging recording analysis. It is used to solve the problem of poor reliability of the side channel attack prevention method in the related art.

[0056] The solution provided by the embodiment of the utility model is described in detail below with reference to the accompanying drawings.

[0057] Figure 2 A schematic diagram of a protection circuit for preventing side channel attacks by charge and discharge recording analysis provided by an embodiment of the utility model includes: a sound collection unit 11, a filtering unit 12 and a signal transmission unit 13; the filtering unit 12 is connected to the sound collection unit 11 and the signal transmission unit 13 respectively; wherein:

[0058] The sound collection unit 11 is used to collect the sound signal generated by the charging and discharging of the capacitor, convert the sound signal into a first electrical signal, and transmit the first electrical signal to the filtering unit 12;

[0059] The filtering unit 12 is used to filter the first electrical signal to obtain a second electrical signal, and transmit the second electrical signal to the signal transmission unit 13;

[0060] The signal transmission unit 13 is used to compress the second electrical signal to obtain a third electrical signal, and transmit the third electrical signal to the electrical signal analysis device.

[0061] The embodiment of the utility model provides a protection circuit for preventing side channel attacks by charging and discharging recording analysis, comprising: a sound collection unit 11, a filtering unit 12 and a signal transmission unit 13; the sound collection unit 11 is connected to the filtering unit 12, and the filtering unit 12 is also connected to the signal transmission unit 13. When the password module in the protection device performs key verification, the change in energy consumption will cause the charging and discharging of the capacitor, and the charging and discharging of the capacitor will make a sound. The sound collection unit 11 can collect the sound signal generated by the charging and discharging of the capacitor, and then convert the sound signal into a first electrical signal, and transmit the first electrical signal to the filtering unit 12. Optionally, the sound collection unit 11 includes a MIC sound collector. The filtering unit 12 performs filtering processing on the first electrical signal to obtain a second electrical signal, and then transmits the second electrical signal to the signal transmission unit 13. Since the first electrical signal directly generated by the charging and discharging sound of the capacitor is filtered by the filtering unit 12, the sound wave of the charging and discharging of the capacitor is obtained through recording analysis, and the risk of calculating the key based on the sound wave of the charging and discharging of the capacitor is avoided. Then, the signal transmission unit 13 compresses the second electrical signal to obtain a third electrical signal, and transmits the third electrical signal to the electrical signal analysis device. Since the electrical signal obtained by the electrical signal analysis device is an electrical signal after filtering and compressing the first electrical signal directly generated by the sound of the capacitor charging and discharging, the electrical signal that can be inferred based on the third electrical signal is also the filtered electrical signal, and the original first electrical signal directly generated by the sound of the capacitor charging and discharging before filtering cannot be inferred, thus solving the problem of inferring the key based on the sound waves of the capacitor charging and discharging, and improving the reliability of preventing side channel attacks.

[0062] Figure 3 The schematic diagram of the protection circuit for preventing the side channel attack by charging and discharging recording analysis provided by the embodiment of the utility model also includes: a signal amplification unit 14; wherein:

[0063] The signal amplifying unit 14 is connected to the filtering unit 12 and the signal transmitting unit 13 respectively;

[0064] The filtering unit 12 is used to filter the first electrical signal to obtain a second electrical signal, and transmit the second electrical signal to the signal amplifying unit 14;

[0065] The signal amplifying unit 14 is used to perform amplitude amplification processing on the second electrical signal, and transmit the second electrical signal after the amplitude amplification processing to the signal transmitting unit 13 .

[0066] The function of the signal amplification unit 14 is to amplify the second electrical signal to a required amplitude value and an electrical signal that is consistent with the variation rule of the second electrical signal. Then the signal amplification unit 14 transmits the second electrical signal after the amplitude amplification process to the signal transmission unit 13. The signal transmission unit 13 compresses the second electrical signal after the amplitude amplification process to obtain a third electrical signal, and transmits the third electrical signal to the electrical signal analysis device.

[0067] The signal amplifying unit comprises: an LM324 amplifier. Figure 4 The pin connection diagram of the LM324 amplifier provided by the utility model is as follows: Figure 4 As shown, the LM324 amplifier is a quad operational amplifier with differential inputs. They have some significant advantages over standard operational amplifiers for single-supply applications. The quad amplifier can operate from supplies as low as 3.0 volts or as high as 32 volts, with a quiescent current of one-fifth that of the 741. The common-mode input range includes the negative supply, eliminating the need for external bias components in many applications. Each set of operational amplifiers has 5 pins, of which "+" and "-" are two signal input terminals, "V+" and "V-" are positive and negative power supply terminals, and "Vo" is the output terminal. Of the two signal input terminals, Vi-(-) is the inverting input terminal, indicating that the signal at the output terminal Vo of the op amp is opposite to that of the input terminal; Vi+(+) is the non-inverting input terminal, indicating that the signal at the output terminal Vo of the op amp is the same phase as that of the input terminal.

[0068] Figure 5 The schematic diagram of the protection circuit for preventing the side channel attack by charging and discharging recording analysis provided by the embodiment of the utility model also includes: an ADC sampling unit 15; wherein:

[0069] The ADC sampling unit 15 is connected to the signal amplification unit 14 and the signal transmission unit 13 respectively;

[0070] The signal amplifying unit 14 is used to perform amplitude amplification processing on the second electrical signal, and transmit the second electrical signal after the amplitude amplification processing to the ADC sampling unit 15;

[0071] The ADC sampling unit 15 is used to sample the second electrical signal after the amplitude amplification processing, and transmit the electrical signal obtained by the sampling processing to the signal transmission unit 13.

[0072] The signal transmission unit 13 compresses the electrical signal obtained by the sampling process to obtain a third electrical signal, and transmits the third electrical signal to the electrical signal analysis device.

[0073] The filter is used in a circuit that is selective to the frequency of the signal. Its function is to allow signals within a specific frequency range to pass through, while preventing signals of other frequencies from passing through. The active filter selected by the utility model has the advantages of standardized design, modularization, and easy manufacturing, and is therefore widely used in circuits such as information processing, data transmission, and interference suppression. An ideal low-pass filter allows all signals below the cutoff frequency to pass losslessly, while all signals above the cutoff frequency are infinitely attenuated, thereby presenting a rectangular shape on the amplitude-frequency characteristic curve, so it is also called a rectangular filter (brick-wall filter). However, the ideal characteristics cannot be achieved, and all designs are only attempts to approximate the characteristics of a rectangular filter. Different responses can be obtained depending on the selected approximation function. Although there are many different approximation functions, considering the actual circuit usage requirements, the utility model uses the "Butterworth response".

[0074] The filtering unit includes: a Butterworth filter. The characteristic of the Butterworth filter is that the frequency response curve in the passband is maximally flat without fluctuations, and gradually decreases to zero in the stopband. On the Bode plot of the logarithm of the amplitude to the diagonal frequency, starting from a certain boundary angular frequency, the amplitude gradually decreases with the increase of the angular frequency and tends to negative infinity. In the embodiment of the utility model, any one of a first-order Butterworth filter, a second-order Butterworth filter, a third-order Butterworth filter, a fourth-order Butterworth filter, an eighth-order Butterworth filter, etc. can be selected.

[0075] A first order Butterworth filter has a decay rate of 6 dB per octave and 20 dB per decade. A second order Butterworth filter has a decay rate of 12 dB per octave, a third order Butterworth filter has a decay rate of 18 dB per octave, and so on. The Butterworth filter has a monotonically decreasing amplitude versus diagonal frequency, and is the only filter that has the same shape of amplitude versus diagonal frequency regardless of order. It's just that the higher the order of the filter, the faster the amplitude decays in the stopband. Other filters have different shapes of amplitude versus diagonal frequency at higher orders than at lower orders.

[0076] The squared magnitude response of the Butterworth low-pass filter is: Where n is the order of the filter and Wc is the cutoff frequency of the low-pass filter.

[0077] Figure 6 The schematic diagram of the amplitude-frequency characteristics of the second-order, fourth-order, and eighth-order Butterworth low-pass filters provided by the embodiments of the present invention is as follows: Figure 6 As shown, the higher the order n, the better the amplitude-frequency characteristic and the higher the fidelity of the low-frequency detection signal.

[0078] The fourth-order active low-pass filter can be composed of two second-order low-pass filters in cascade. The transfer function of the fourth-order Butterworth low-pass filter is designed. Two second-order Butterworth low-pass filters are used to form a fourth-order Butterworth low-pass filter, and its transfer function is:

[0079]

[0080] In order to simplify the calculation, its parameters meet the following conditions:

[0081]

[0082] Select C = 0.01uF, and you can get R = 796Ω.

[0083] The two damping coefficients of the fourth-order Butterworth low-pass filter are: -0.765, 1.848, from which the two zero-frequency gains are calculated as:

[0084] G 01 =3-ξ1=3-0.765=2.235; G 02 =3-ξ2=3-1.848=1.152;

[0085] Then the transfer function is:

[0086]

[0087] Two second-order Butterworth low-pass filters can be cascaded. The gains are:

[0088]

[0089]

[0090] For the first stage, if R3=61KΩ, then R4=9.27KΩ;

[0091] For the second stage, if R7=20KΩ is selected, then R4=24.7KΩ.

[0092] Figure 7 The circuit diagram of the filter unit provided by the utility model includes: a first resistor R1, a second resistor R2, a first capacitor C1, a second capacitor C2, a first operational amplifier U1, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a third capacitor C3, a fourth capacitor C4, a second operational amplifier U2, a seventh resistor R7 and an eighth resistor R8;

[0093] One end of the first resistor R1 is connected to the sound collection unit 11; the other end of the first resistor R1 is respectively connected to one end of the second resistor R2 and one end of the first capacitor C1; the other end of the second resistor R2 is respectively connected to one end of the second capacitor C2 and the positive input pin of the first operational amplifier U1; the other end of the second capacitor C2 is grounded; one end of the third resistor R3 is grounded, and the other end is respectively connected to one end of the fourth resistor R4 and the negative input pin of the first operational amplifier U1; the other end of the fourth resistor R4 is respectively connected to the output pin of the first operational amplifier U1, one end of the fifth resistor R5 and one end of the first capacitor C1 not connected to the first resistor R1; the positive power supply pin of the first operational amplifier U1 is connected to the positive power supply, and the negative power supply pin of the first operational amplifier U1 is connected to the negative power supply;

[0094] One end of the fifth resistor R5 that is not connected to the fourth resistor R4 is respectively connected to one end of the sixth resistor R6 and one end of the third capacitor C3; the other end of the sixth resistor R6 is respectively connected to one end of the fourth capacitor C4 and the positive input pin of the second operational amplifier U2; the other end of the fourth capacitor C4 is grounded; one end of the seventh resistor R7 is grounded, and the other end is respectively connected to one end of the eighth resistor R8 and the negative input pin of the second operational amplifier U2; the other end of the eighth resistor R8 is respectively connected to the output pin of the second operational amplifier U2 and one end of the third capacitor C3 that is not connected to the fifth resistor R5; the positive power supply pin of the second operational amplifier U2 is connected to the positive power supply, and the negative power supply pin of the second operational amplifier U2 is connected to the negative power supply.

[0095] The recording signal collected by the sound collection unit is connected to the first resistor R1, and is filtered by a 4th-order Butterworth filter to remove the high-frequency signal, and the low-frequency signal can pass through. The filtered signal is connected to the signal amplification unit through the output end of the second operational amplifier. Optionally, the high-frequency signal removed is a signal higher than 20KHz, and the low-frequency signal passed is a signal below 20KHz.

[0096] Figure 8 The schematic diagram of the protection circuit for preventing the side channel attack by charging and discharging recording analysis provided by the utility model also includes: an oscilloscope 16 for testing the frequency filtering transient characteristics of the filtering unit; wherein:

[0097] One end of the first resistor R1 connected to the sound collection unit 11 is connected to the A channel pin of the oscilloscope 16 ; the output end of the second operational amplifier U2 is connected to the B channel pin of the oscilloscope 16 .

[0098] Fig. 9 This is a schematic diagram of the observation results of the oscilloscope when the frequency fi=1KHZ and the voltage Vi=2.5V provided by the utility model. Fig.10 This is a schematic diagram of the observation results of the oscilloscope when the frequency fi is 20KHZ and the voltage Vi is 2.5V provided by the utility model; Fig.11 This is a schematic diagram of the observation results of the oscilloscope when the frequency fi = 50KHZ and the voltage Vi = 2.5V provided by the utility model. It can be seen from the above figure that when the input signal is 2.5V and 1KHz, the input and output waveforms are as follows Fig. 9 As shown, the amplitude is magnified by 2.6 times; when the input signal becomes 50KHz, Fig.11 The output signal is almost attenuated to 0, which shows that the filter has a strong inhibitory effect on signals greater than the cutoff frequency.

[0099] Fig.12 The schematic diagram of the protection circuit for preventing the side channel attack by charging and discharging recording analysis provided by the utility model also includes: a baud meter 17 for testing the frequency characteristics of the filtering unit; wherein:

[0100] One end of the first resistor R1 connected to the sound collection unit 11 is connected to the signal input pin of the baud meter 17 ; the output end of the second operational amplifier U3 is connected to the signal output pin of the baud meter 17 .

[0101] Fig.13 A schematic diagram of the analysis results of the amplitude-frequency characteristics of the first baud meter provided by the utility model; Fig.14 A schematic diagram of the analysis results of the amplitude-frequency characteristics of the second baud meter provided by the utility model; Fig.15 A schematic diagram of the analysis results of the amplitude-frequency characteristics of the third baud meter provided by the utility model; Fig.16 This is a schematic diagram of the analysis results of the amplitude-frequency characteristics of the fourth baud meter provided by the utility model.

[0102] Since the signal is amplified 2.6 times by the filter, Fig.13 It can be seen that the corresponding logarithmic coordinate is 8.219dB, minus 3dB is the corresponding cutoff frequency, so the vertical coordinate corresponding to the cutoff frequency on the Bode plotter should be 5.219dB. Fig.14 It can be seen that the cutoff frequency of the filter is about 20.454kHz, which is consistent with the theoretical calculated value. When the frequency begins to decay, observe Fig.15 , we can see that the starting frequency is about 16.832; when the frequency is adjusted to 60.583kHz, Fig.16 As shown, the corresponding ordinate is approximately equal to -31.974dB. It can be seen that the filter can effectively attenuate high-frequency signals and has good filtering characteristics.

[0103] The utility model removes the sound signals above 20kHz by adding a low-pass filter circuit to the recording signal link, thereby making it impossible to obtain the recording file of the capacitor charging and discharging. It directly avoids obtaining the energy consumption waveform during key verification from the source, directly avoiding the possibility of stealing the key through side channel attacks through recording analysis, and does not increase the key verification time and affect the user experience. It makes full use of the frequency selection passability of the active filter to remove the sound of the capacitor charging and discharging during the key calculation in the recording file. The hardware implementation will not increase the delay of the recording communication and will not affect the user experience; remove the sound of the capacitor charging and discharging during the key calculation from the recording link to prevent the acquisition of the recording file of the capacitor charging and discharging sound, and prevent side channel attacks from the source; the key information encoding algorithm is not changed, and the computing cost is not increased.

[0104] 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 charge and discharge recording analysis 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 charge and discharge recording analysis, so the implementation of the encryption chip can refer to the implementation of the protection circuit for preventing side channel attacks by charge and discharge recording analysis, and the repeated parts will not be repeated.

[0105] 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.

[0106] 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.

[0107] 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 charge and discharge recording analysis, characterized in that: include: Sound collection unit, filtering unit and signal transmission unit; The filtering unit is connected to the sound collection unit and the signal transmission unit respectively; wherein: The sound collection unit is used to collect the sound signal generated by the charging and discharging of the capacitor, convert the sound signal into a first electrical signal, and transmit the first electrical signal to the filtering unit; The filtering unit is used to filter the first electrical signal to obtain a second electrical signal, and transmit the second electrical signal to the signal transmission unit; The signal transmission unit is used to compress the second electrical signal to obtain a third electrical signal, and transmit the third electrical signal to the electrical signal analysis device.

2. The circuit according to claim 1, characterized in that Also includes: A signal amplification unit; wherein: The signal amplifying unit is connected to the filtering unit and the signal transmitting unit respectively; The filtering unit is used to filter the first electrical signal to obtain a second electrical signal, and transmit the second electrical signal to the signal amplifying unit; The signal amplifying unit is used to perform amplitude amplification processing on the second electrical signal, and transmit the second electrical signal after the amplitude amplification processing to the signal transmission unit.

3. The circuit according to claim 2, characterized in that Also includes: ADC sampling unit; where: The ADC sampling unit is connected to the signal amplifying unit and the signal transmitting unit respectively; The signal amplifying unit is used to perform amplitude amplification processing on the second electrical signal, and transmit the second electrical signal after the amplitude amplification processing to the ADC sampling unit; The ADC sampling unit is used to sample the second electrical signal after the amplitude amplification processing, and transmit the electrical signal obtained by the sampling processing to the signal transmission unit.

4. The circuit according to claim 1, characterized in that The filtering unit includes: a Butterworth filter.

5. The circuit according to claim 4, characterized in that The filtering unit includes: a first resistor, a second resistor, a first capacitor, a second capacitor, a first operational amplifier, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a third capacitor, a fourth capacitor, a second operational amplifier, a seventh resistor and an eighth resistor; One end of the first resistor is connected to the sound collection unit; the other end of the first resistor is respectively connected to one end of the second resistor and one end of the first capacitor; the other end of the second resistor is respectively connected to one end of the second capacitor and the positive input pin of the first operational amplifier; the other end of the second capacitor is grounded; one end of the third resistor is grounded, and the other end is respectively connected to one end of the fourth resistor and the negative input pin of the first operational amplifier; the other end of the fourth resistor is respectively connected to the output pin of the first operational amplifier, one end of the fifth resistor, and one end of the first capacitor that is not connected to the first resistor; the positive power supply pin of the first operational amplifier is connected to the positive power supply, and the negative power supply pin of the first operational amplifier is connected to the negative power supply; One end of the fifth resistor that is not connected to the fourth resistor is respectively connected to one end of the sixth resistor and one end of the third capacitor; the other end of the sixth resistor is respectively connected to one end of the fourth capacitor and the positive input pin of the second operational amplifier; the other end of the fourth capacitor is grounded; one end of the seventh resistor is grounded, and the other end is respectively connected to one end of the eighth resistor and the negative input pin of the second operational amplifier; the other end of the eighth resistor is respectively connected to the output pin of the second operational amplifier and one end of the third capacitor that is not connected to the fifth resistor; the positive power supply pin of the second operational amplifier is connected to the positive power supply, and the negative power supply pin of the second operational amplifier is connected to the negative power supply.

6. The circuit according to claim 2, characterized in that The signal amplifying unit comprises: an LM324 amplifier.

7. The circuit according to claim 5, characterized in that Also includes: An oscilloscope for testing the frequency filtering transient characteristics of the filtering unit; wherein: One end of the first resistor connected to the sound collection unit is connected to the A channel pin of the oscilloscope; and the output end of the second operational amplifier is connected to the B channel pin of the oscilloscope.

8. The circuit according to claim 5, characterized in that Also includes: A baud meter for testing the frequency characteristics of the filtering unit; wherein: One end of the first resistor connected to the sound collection unit is connected to the signal input pin of the baud meter; and the output end of the second operational amplifier is connected to the signal output pin of the baud meter.

9. An encryption chip, characterized in that: It comprises a protection circuit for preventing side channel attacks by charge and discharge recording analysis 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.

Images