TWI844836B - Power supplying device, method and secure system - Google Patents

Abstract

A power supply device for providing a driving voltage of an encryption and decryption device. When the encryption/decryption device operates and the drive voltage falls within the voltage range formed by the upper limit voltage and the lower limit voltage, only the supply voltage provided by the secure power supply device is used as the drive voltage for the encryption/decryption device. When the encryption and decryption device operates and the driving voltage falls outside the voltage range formed by the upper limit voltage and the lower limit voltage, the supply voltage and the stable voltage provided by the stable voltage source are used as the driving voltage at the same time, the supply voltage is further adjusted until the driving voltage falls within the voltage range formed by the upper limit voltage and the lower limit voltage, and then continue to use only the supply voltage as the driving voltage.

Description

Power supply device, method and safety system

The present invention relates to a power supply device, method and security system, and in particular to a power supply device, method and security system that can prevent hackers from maliciously stealing security information by detecting changes in system voltage of a power supply and changes in its corresponding current value.

In recent years, security applications have been implemented in many areas, including identity cards, credit cards, computer access control, and mobile phones (e.g., SIM cards). These applications usually rely on cryptographic calculations based on keys embedded in memory to achieve high security. Hackers will try to extract these keys from the card to generate unauthorized transactions. Side channel attacks are the most common method to collect information from a card or computer system during normal operation. It can decrypt the keys based on timing information, power consumption, and electromagnetic fields. Therefore, keeping data secure and avoiding side channel attacks are factors that need to be considered when designing a secure system.

The power side channel attack is described as follows. During the switching of the logic gate of the encryption device (implemented by multiple logic gates), the hacker can detect the current change and the power characteristics generated by the current change (usually the driving voltage applied to the encryption device will also change with the current change), and monitor these power characteristics through the power pins to recover the key. In order to prohibit reading the power and ground signals from the logic gate, the power pins and ground pins are usually isolated from the external pads.

Please refer to FIG. 1, which is a circuit diagram of a security system of the prior art. The security system 1 includes a power supply 10, a power supply device 12, and an encryption device 14, wherein the power supply device 12 is electrically connected between the power supply 10 and the encryption device 14 to prevent hackers from obtaining power supply characteristics related to security information by detecting the power pins and ground pins of the power supply 10. The power supply device 12 includes a plurality of switches SW1 to SW5 and a charge storage capacitor CS. One end of the switch SW1 is electrically connected to the system voltage of the power supply 10, and the other end of the switch SW1 is electrically connected to one end of the switch SW2, one end of the switch SW5, and one end of the charge storage capacitor CS. The other end of the switch SW2 is electrically connected to one end of the encryption device 14, thereby outputting a supply voltage to the encryption device 14 as a driving voltage of the encryption device 14. One end of the switch SW3 is electrically connected to the ground voltage of the power source 10. The other end of the switch SW3 is electrically connected to one end of the switch SW4, the other end of the switch SW5 and the other end of the charge storage capacitor CS. The other end of the switch SW4 is electrically connected to the other end of the encryption device 14 to provide a ground voltage to the encryption device 14.

The process of the power supply device 12 providing the supply voltage is as follows. First, in the first stage, only the switch SW5 is turned on, and the other switches SW1 to SW4 are turned off to discharge the charge storage capacitor CS to a specific voltage level, that is, the switch SW5 is used as a reset switch. In the second stage, the switches SW1 and SW3 are turned on, and the other switches SW2, SW4, and SW5 are turned off, so the system voltage of the power supply 10 can charge the charge storage capacitor CS. After charging to the voltage level of the system voltage, it enters the third stage. In the third stage, the switches SW2 and SW4 are turned on, and the other switches SW1, SW3, and SW5 are turned off, and the charge storage capacitor CS provides the supply voltage to the encryption and decryption device 14 as a driving voltage. Then, in the fourth stage, the encryption and decryption device 14 is allowed to perform encryption and decryption. After the fourth stage is finished, it returns to the first stage again.

Through the above method, although it is possible to prevent hackers from obtaining power supply characteristics related to security information through the power pin and the ground pin of the detection power supply 10, the above method must ensure that the amount of charge stored in the charge storage capacitor CS must be able to supply the large amount of charge consumed by the encryption and decryption device 14 during encryption and decryption, so this results in the size of the charge storage capacitor CS to be large enough. Furthermore, the above method is not a power-saving solution, because the above method must discharge the charge storage capacitor CS to a predetermined voltage level in the first stage. In addition, the larger the size of the charge storage capacitor CS, the longer the charging and discharging time will be, which will be more time-consuming overall, not to mention that the above method requires a total of four stages to ensure that the encryption and decryption device 14 can work normally.

An embodiment of the present invention provides a power supply device, which is used to provide power to the encryption device of the security system, and includes a safe power supply device, a stable voltage source and a voltage selection device. The safe power supply device is used to provide a supply voltage, wherein the supply voltage can be dynamically adjusted according to the operation of the encryption device. The stable voltage source is used to provide a stable voltage. The voltage selection device is electrically connected to the safe power supply device, the stable voltage source and the encryption device. When the encryption device is in operation and the driving voltage of the encryption device falls within the voltage range formed by the upper limit voltage and the lower limit voltage, the voltage selection device only uses the supply voltage as the driving voltage of the encryption device. When the encryption and decryption device performs encryption and decryption and the driving voltage is outside the voltage range, the voltage selection device uses the supply voltage and the stable voltage as the driving voltage of the encryption and decryption device, and adjusts the supply voltage until the driving voltage falls into the voltage range.

The embodiment of the present invention also provides a security system, which includes the power supply device and the encryption and decryption device.

The embodiment of the present invention also provides a power supply method, which is used to provide power to the encryption and decryption device of the security system, and performs the following steps. When the encryption and decryption device is in operation and the driving voltage of the encryption and decryption device is greater than the upper limit voltage, the supply voltage provided by the security power supply device and the stable voltage provided by the stable voltage source are used as the driving voltage, and the supply voltage is reduced until the driving voltage is less than the upper limit voltage, and then only the supply voltage is used as the driving voltage. When the encryption and decryption device is in operation and the driving voltage is less than the lower limit voltage, the supply voltage and the stable voltage are used as the driving voltage, and the supply voltage is increased until the driving voltage is greater than the lower limit voltage, and then only the supply voltage is used as the driving voltage. When the encryption and decryption device is in operation and the driving voltage is not greater than the upper limit voltage and not less than the lower limit voltage, only the supply voltage is used as the driving voltage.

The embodiment of the present invention provides a power supply device, which is used to provide power to the encryption and decryption device of the security system, and includes a safe power supply device, a stable voltage source and a voltage selection device. The safe power supply device is used to provide a supply voltage according to the system voltage, wherein the supply voltage can be dynamically adjusted according to the operation of the encryption and decryption device. The stable voltage source is used to provide a stable voltage. The voltage selection device is electrically connected to the safe power supply device, the stable voltage source and the encryption and decryption device. When the encryption device is in operation and the driving voltage of the encryption device is within the voltage range formed by the upper voltage limit and the lower voltage limit, the voltage selection device uses only the supply voltage as the driving voltage of the encryption device. When the encryption device is in operation and the driving voltage is outside the voltage range, the voltage selection device uses only the stable voltage as the driving voltage of the encryption device, and after adjusting the supply voltage until the driving voltage is within the voltage range, only the supply voltage is used as the driving voltage of the encryption device.

In summary, compared with the prior art, the various power supply devices, methods and security systems provided by the embodiments of the present invention can achieve at least one of the technical effects of reducing the size, operation time, power consumption current and circuit area required for the charge storage capacitor. The power supply device of the embodiments of the present invention can effectively protect the security system and prevent hackers from obtaining security information through the power characteristics detected by the power pins and the ground pins.

In order to further understand the technology, means and effects of the present invention, the following detailed description and drawings may be referred to, so that the purpose, features and concepts of the present invention can be thoroughly and specifically understood. However, the following detailed description and drawings are only used for reference and explanation of the implementation of the present invention, and are not used to limit the present invention.

Reference will now be made in detail to exemplary embodiments of the present invention, which are illustrated in the accompanying drawings. Where possible, the same reference numerals are used in the drawings and the specification to refer to the same or similar components. In addition, the exemplary embodiments are only one of the implementation methods of the design concept of the present invention, and the following examples are not intended to limit the present invention.

To solve the problems of the prior art, the various power supply devices, methods and security systems provided by the embodiments of the present invention can prevent hackers from obtaining security information through the power characteristics detected by the power pins and the ground pins, and while achieving the security protection effect, can also achieve at least one of the technical effects of reducing the size, operation time, power consumption current and circuit area required for the charge storage capacitor.

In the embodiment of the present invention, the power supply device includes a safe power supply device, a stable voltage source and a voltage selection device, wherein the voltage selection device is electrically connected to the safe power supply device, the stable voltage source and the encryption device. When the encryption device performs encryption and decryption (i.e., the encryption device operates), the voltage selection device monitors the driving voltage of the encryption device. When the driving voltage is between the upper limit voltage and the lower limit voltage, the voltage selection device selects the supply voltage provided by the safe power supply device as the driving voltage of the encryption device; and when the driving voltage is greater than the upper limit voltage or less than the lower limit voltage (i.e., outside the voltage range formed by the upper limit voltage and the lower limit voltage), the voltage selection device will simultaneously select the stable voltage provided by the stable voltage source and the supply voltage provided by the safe power supply device as the driving voltage of the encryption device.

Furthermore, when the driving voltage is greater than the upper voltage limit, the voltage selection device will also reduce the supply voltage provided by the safety power supply device until the driving voltage is reduced to less than the upper voltage limit. Furthermore, when the driving voltage is less than the lower voltage limit, the voltage selection device will also increase the supply voltage provided by the safety power supply device until the driving voltage is increased to greater than the upper voltage limit.

The voltage selection device may include a switching mode controller and a switching switch. During the startup period, the switching mode controller controls the switching switch to be turned on, and only the stable voltage source provides a stable voltage to the encryption device as a driving voltage. During the startup period, the driving voltage of the encryption device will gradually increase. When it rises to a target voltage value (for example, another system voltage lower than the maximum system voltage) and continues for a period of time, the startup period ends. After the startup period ends, the switching mode controller controls the switching switch to open or close according to whether the encryption and decryption device needs to perform encryption and decryption, so as to determine whether the security power supply device provides the supply voltage to the encryption and decryption device as the driving voltage, or whether the stable voltage source provides the stable voltage to the encryption and decryption device as the driving voltage.

This method allows the stable voltage source to maintain the driving voltage at a stable voltage when the encryption device is not performing encryption and decryption after the startup period ends. Only when the encryption device is performing encryption and decryption and the driving voltage is within the voltage range of the upper limit voltage and the lower limit voltage, the security power supply device will provide the supply voltage to the encryption device as the driving voltage. When the driving voltage exceeds the voltage range, the stable voltage and the supply voltage are used as the driving voltage at the same time, and the size of the supply voltage is adjusted at the same time so that the driving voltage can fall within the voltage range. Accordingly, the power supply device provided by the embodiment of the present invention can solve the technical problem that the encryption device needs to consume a large amount of current when performing encryption and decryption, resulting in a sudden drop in the driving voltage. Compared with the previous technology, the method of this embodiment can still effectively reduce the size, operation time, power consumption current and circuit area required by the charge storage capacitor.

First, please refer to FIG. 2, which is a circuit diagram of a security system according to an embodiment of the present invention. The security system 2 includes a power supply device 20 and an encryption device 22, wherein the power supply device 20 includes a stable voltage source 200, a switching mode controller 202, a safety power supply device 204, and a switching switch 206, wherein the switching mode controller 202 and the switching switch 206 constitute a voltage selection device. The power supply device 20 is used to provide power to the encryption device 22 of the security system 2, and its main purpose is to prevent hackers from obtaining security information by detecting power characteristic changes obtained by the power pin and the ground pin (i.e., power characteristic changes of the system voltage). In other words, during the encryption and decryption process of the encryption and decryption device 22, the power supply characteristics of the system voltage will not change significantly.

The safety power supply device 204 is used to generate a supply voltage according to the system voltage and provide the supply voltage, wherein the supply voltage is applied to the encryption device 22 as a driving voltage VDIG for driving the encryption device 22 (related to the on and off of the switch 206), and the supply voltage can be dynamically adjusted according to the operation of the encryption device. Through the safety power supply device 204, when the encryption device 22 performs encryption and decryption, the power supply characteristic variation of the system voltage can be less than a specific range, for example, the current or voltage variation is less than 5%, but the present invention is not limited to this. However, when only the safety power supply device 204 provides the supply voltage as the driving voltage VDIG of the encryption device 22, it may not be able to provide a sufficient total output current to the encryption device 22 as the current consumed in encryption and decryption. That is, when the switching current unit opened in the safety power supply device 204 to provide current is insufficient, it is impossible to provide a sufficient total output current to the encryption device 22. Therefore, the stable voltage source 200, the switching mode controller 202 and the switching switch 206 are provided in the power supply device 20 to solve the above technical problems.

The stabilized voltage source 200 is used to provide a stable voltage that is not susceptible to changes, wherein the stabilized voltage source 200 can be implemented by a DC-to-DC converter such as a bandgap voltage generator, a low-dropout voltage regulator, etc., for example but not limited to, by the comparator CMP1, the resistor R1 and the PMOS transistor MP1 of FIG. 2 . The switching mode controller 202 is electrically connected to the encryption device 22, and is used to generate a first switch signal, and generate a second switch signal according to the first switch signal and the drive voltage VDIG of the encryption device 22, wherein the first switch signal is determined according to the encryption and decryption working signal ENCRP (as shown in FIG. 3 and FIG. 4) used to indicate whether the encryption and decryption device 22 performs encryption and decryption and two output signals OUT1 and OUT2 (as shown in FIG. 3) used to indicate whether the drive voltage VDIG exceeds the voltage range formed by the upper limit voltage and the lower limit voltage. One implementation of the switching mode controller 202 is shown in FIG. 3, and its details will be introduced in the following description, and the present invention is not limited thereto. The switch 206 has a first end, a second end and a control end, wherein the first end is electrically connected to the stable voltage source 200, the second end is electrically connected to the encryption device 22, and the control end is electrically connected to the switching mode controller 202 to receive the first switch signal. The conduction or disconnection of the switch 206 (i.e., the conduction or disconnection of the first end and the second end) is controlled by the first switch signal.

The total output current generated by the safety power supply device 204 is controlled by the second switch signal. When the encryption and decryption device 22 performs encryption and decryption, the supply voltage is first used as the driving voltage VDIG. However, if the current consumption of the encryption and decryption device 22 increases and the driving voltage VDIG of the encryption and decryption device 22 drops below the lower limit voltage, the first switch signal switches the switch 206 so that the stable voltage and the supply voltage are used as the driving voltage VDIG at the same time. At the same time, the second switch signal is updated and controls the safety power supply device 204 to increase the total output current of the safety power supply device 204, thereby increasing the supply voltage and the driving voltage VDIG. Then, the driving voltage VDIG returns to the voltage range formed by the upper limit voltage and the lower limit voltage, and the first switch signal switches the switch 206, and the supply voltage is used as the driving voltage VDIG. Compared with the previous supply voltage, the supply voltage has been increased this time, so only the supply voltage can be used as the driving voltage VDIG again.

On the other hand, when the encryption and decryption device 22 performs encryption and decryption, the supply voltage is first used as the driving voltage VDIG. However, when the driving voltage VDIG of the encryption and decryption device 22 rises to a level higher than the upper limit voltage, the first switch signal switches the switch 206, and uses the stable voltage and the supply voltage as the driving voltage VDIG at the same time. At the same time, the second switch signal is updated and controls the safety power supply device 204 to reduce the total output current of the safety power supply device 204, thereby reducing the supply voltage and the driving voltage VDIG. Then, the driving voltage VDIG returns to the voltage range formed by the upper limit voltage and the lower limit voltage, and the first switch signal switches the switch 206, using the supply voltage as the driving voltage VDIG. Compared with the previous supply voltage, the supply voltage has been lowered this time, so only the supply voltage can be used as the driving voltage VDIG again.

Then, when the encryption/decryption device 22 is not performing encryption/decryption or is in the startup period, only the stable voltage source 200 provides the stable voltage to the encryption/decryption device 22 as the driving voltage VDIG. Therefore, the first switching signal generated by the switching mode controller 202 causes the security power supply device 204 not to provide the supply voltage and generate the total output current to the encryption/decryption device 22.

Please refer to FIG. 1 and FIG. 4 at the same time. FIG. 4 is a waveform diagram of some signals of the security system of the embodiment of the present invention. During the startup period (interval T1), the switching mode controller 202 generates a first switch signal to turn on the switching switch 206 (the first end and the second end of the switching switch 206 are turned on), and the security power supply device 204 does not provide a supply voltage, and the encryption and decryption device 22 only receives a stable voltage as a driving voltage VDIG. After the driving voltage VDIG reaches or approaches the target value of the driving voltage VDIG, the startup period (interval T1) ends, and the switching mode controller 202 generates a first switching signal to turn on the switching switch 206 (the first end and the second end of the switching switch 206 are turned on), and the security power supply device 204 does not provide a supply voltage, so that the encryption and decryption device 22 only receives a stable voltage as the driving voltage VDIG.

After the start-up period (interval T1) ends, the switching mode controller 202 determines whether to use the supply voltage as the driving voltage VDIG according to the encryption and decryption working signal ENCRP. In the interval T2 after the interval T1, the encryption and decryption device 22 does not perform encryption and decryption, the first switch signal turns on the switching switch 206, and the safety power supply device 204 does not provide the supply voltage, so the encryption and decryption device 22 only receives the stable voltage as the driving voltage VDIG.

In the interval T3, the encryption and decryption device 22 performs encryption and decryption (the encryption and decryption working signal ENCRP is a logical high level). If the driving voltage VDIG is within the voltage range formed by the upper voltage limit and the lower voltage limit, the first switch signal disconnects the switching switch 206, and the second switch signal causes the safety power supply device 204 to output the total current and provide the supply voltage to the encryption and decryption device 22 as the driving voltage VDIG. In the interval T3, if the driving voltage VDIG exceeds the voltage range formed by the upper voltage limit and the lower voltage limit, the first switch signal turns on the switching switch 206 and switches to use the stable voltage and the supply voltage as the driving voltage VDIG. Furthermore, when the regulated voltage and the supply voltage are used as the driving voltage VDIG, if the driving voltage VDIG is greater than the upper voltage limit, the second switch signal will cause the supply voltage to decrease until the driving voltage VDIG is less than the upper voltage limit, and then the supply voltage will be used as the driving voltage VDIG and the supply voltage reduction will stop. Similarly, when the stable voltage and the supply voltage are used as the driving voltage VDIG, if the driving voltage VDIG is less than the lower limit voltage, the second switch signal will cause the supply voltage to rise until the driving voltage VDIG is greater than the lower limit voltage, and then only the supply voltage is used as the driving voltage VDIG and the supply voltage is stopped from being raised. In the interval T4 after the interval T3, the encryption and decryption device 22 does not perform encryption and decryption, the first switch signal turns on the switching switch 206, and causes the safety power supply device 204 to not provide the supply voltage, so the encryption and decryption device 22 only receives the stable voltage as the driving voltage VDIG.

Incidentally, although in the embodiment of the present invention, a stable voltage is used as the driving voltage VDIG during the startup period and the non-encryption and decryption period, the present invention is not limited to this. In other cases, the supply voltage may also be used as the driving voltage VDIG.

Please continue to refer to FIG. 2 , the stabilized voltage source 200 may include a PMOS transistor MP1, a comparator CMP1, and a resistor R1. The source of the PMOS transistor MP1 is electrically connected to the system voltage VDD. The output of the comparator CMP1 is electrically connected to the gate of the PMOS transistor, the negative input of the comparator CMP1 receives a voltage lower than the target voltage value (e.g., another system voltage DVDD lower than the system voltage VDD), and the positive input of the comparator CMP1 is electrically connected to the first end of the switching switch 206 and the drain of the PMOS transistor MP1. The resistor R1 has two ends electrically connected to the drain of the PMOS transistor MP1 and a low voltage (e.g., a ground voltage), respectively. The above structure forms a negative feedback circuit, so that when the comparator CMP1 is in a stable state, the voltage values on the positive input terminal and the negative input terminal of the comparator CMP1 are the same.

One implementation of the safety power supply device 204 is described as follows, but the present invention is not limited thereto. The safety power supply device 204 includes a plurality of switching current units CU1-CUn, wherein a plurality of terminals of the plurality of switching current units CU1-CUn are electrically connected to the system voltage VDD, and another plurality of terminals of the plurality of switching current units CU1-CUn are electrically connected to each other and used to output the supply voltage as the driving voltage VDIG, and the plurality of switching current units CU1-CUn are controlled by a plurality of third switch signals, wherein the second switch signal includes a plurality of third switch signals.

The switching current unit CU1 includes a current source CR1 and a switch SC1, wherein one end of the current source CR1 is electrically connected to the system voltage VDD, two ends of the switch SC1 are electrically connected to the other end of the current source CR1 and the system voltage VDD, and the switch SC1 is controlled by a second switch signal. Similarly, the switching current unit CU2 includes a current source CR2 and a switch SC2, the switching current unit CU3 includes a current source CR3 and a switch SC3, the switching current unit CUn includes a current source CRn and a switch SCn, and the electrical connection method between each of the current sources CR2, CR3, CRn and the corresponding switches SC2, SC3, SCn is similar to the electrical connection method between the current source CR1 and the switch SC1, so it is not repeated.

When the encryption and decryption device 22 performs encryption and decryption, the current consumption of the encryption and decryption device 22 increases, and the driving voltage VDIG decreases. When the driving voltage VDIG is less than the lower limit voltage VTG-Δ, the second switch signal (including multiple third switch signals) generated by the switching mode controller 202 increases the number of multiple switching current units CU1~CUn that are turned on, so as to increase the total output current of the multiple switching current units CU1~CUn to increase the voltage value of the driving voltage VDIG, where Δ is the differential voltage. The total output current of the multiple switching current units CU1~CUn may be excessive, causing the driving voltage VDIG to rise. When the driving voltage VDIG is greater than the upper limit voltage VTG+Δ, the second switch signal (including multiple third switch signals) generated by the switching mode controller 202 will increase the number of multiple switching current units CU1~CUn that are closed, thereby reducing the total output current of the multiple switching current units CU1~CUn to reduce the voltage value of the driving voltage VDIG.

Incidentally, the power supply device 2 may further include a capacitor C1 connected in parallel to the encryption device 22 and/or a ripple suppression unit 208 connected in parallel to the encryption device 22. The capacitor C1 connected in parallel to the encryption device 22 and/or the ripple suppression unit 208 connected in parallel to the encryption device 22 may more effectively maintain the stability of the driving voltage, wherein the ripple suppression unit 208 may be a PMOS transistor MP2 whose gate receives a fixed bias voltage VLEED, and the source and drain of the PMOS transistor MP2 receive the driving voltage VDIG and a low voltage (e.g., a ground voltage) respectively, so that the ripple when the driving voltage VDIG changes can be reduced.

Please refer to FIG. 3, which is a circuit diagram of a switching mode controller of an embodiment of the present invention. One implementation of the switching mode controller 202 may be as shown in FIG. 3, but the present invention is not limited thereto. The switching mode controller 202 includes comparators CMP2, CMP3, a counter CNT1, and a logic circuit LG1. The comparator CMP2 has a positive input terminal and a negative input terminal for receiving an upper limit voltage VTG+Δ and a driving voltage VDIG, respectively. The comparator CMP3 has a positive input terminal and a negative input terminal for receiving a driving voltage VDIG and a lower limit voltage VTG-Δ, respectively. The counter CNT1 has two input terminals electrically connected to the output terminals of the comparator CMP2 and the comparator CMP3 respectively, is enabled or not determined by the first switch signal, and is used to count up or down the output signals of the comparator CMP2 and the comparator CMP3 to generate the second switch signal.

Further, when the first switch signal turns on the switching switch 206, the counter CNT1 is disabled, and therefore, the safety power providing device 204 does not provide a supply voltage. Further, when the first switch signal turns off the switching switch 206, the counter CNT1 is enabled, and therefore, the safety power providing device 204 increases or decreases the total output current according to the second switch signal output by the counter CNT1 to adjust the size of the driving voltage VDIG.

The logic circuit LG1 is used to receive the output signals OUT1 and OUT2 of the comparators CMP1 and CMP2 and the encryption and decryption working signal ENCRP to generate a first switch signal, and the first switch signal is transmitted to the switching switch 206 and the counter CNT1. Please refer to FIG. 3 and FIG. 4 at the same time. Since the switching switch 206 will not be turned on only when the output signals OUT1 and OUT2 are at a logical high level (the driving voltage is within the voltage range) and the encryption and decryption working signal ENCRP is at a logical high level (encryption and decryption are performed), the logic circuit LG1 can be an AND gate, and the present invention is not limited to this.

Please refer to FIG. 5, which is a flow chart of a power supply method of an embodiment of the present invention. This power supply method is used to provide power to the encryption and decryption device of the security system, and can be executed by the above-mentioned power supply device, and includes the following steps. First, in step S102, during the startup period, the stable voltage source provides a stable voltage to the encryption and decryption device as a driving voltage, and after the driving voltage approaches the target voltage value, the startup period ends, and after the startup period ends, the stable voltage source continues to provide a stable voltage to the encryption and decryption device as a driving voltage. Next, in step S104, it is determined whether the encryption/decryption device is to perform encryption/decryption. If it is determined that the encryption/decryption device is not to perform encryption/decryption, step S106B is executed; otherwise, step S106A is executed. In step S106A, when the driving voltage falls within the voltage range formed by the upper limit voltage and the lower limit voltage, the safe power supply device provides the supply voltage to the encryption device as the driving voltage. If the driving voltage exceeds the voltage range formed by the upper limit voltage and the lower limit voltage, the supply voltage and the stable voltage are provided as the driving voltage at the same time, and the supply voltage is adjusted accordingly until the driving voltage falls within the voltage range, and only the supply voltage continues to be used as the driving voltage. In step S106B, the stable voltage source provides the stable voltage to the encryption device as the driving voltage.

In another embodiment of the present invention, the power supply device includes a safe power supply device, a stable voltage source and a voltage selection device, wherein the voltage selection device is electrically connected to the safe power supply device, the stable voltage source and the encryption device. When the encryption device performs encryption and decryption, the voltage selection device monitors the driving voltage of the encryption device. When the driving voltage is between the upper limit voltage and the lower limit voltage, the voltage selection device only selects the supply voltage provided by the safe power supply device as the driving voltage of the encryption device; and when the driving voltage is greater than the upper limit voltage or less than the lower limit voltage (that is, exceeding the voltage interval formed by the upper limit voltage and the lower limit voltage), the voltage selection device only selects the stable voltage provided by the stable voltage source as the driving voltage of the encryption device, and at the same time continuously increases or decreases the supply voltage. This embodiment requires an additional switch to control the supply voltage of the safety power supply device, and it may be difficult to adjust the supply voltage to fall within the voltage range immediately and quickly. The previous embodiment is easier to adjust the supply voltage to fall within the voltage range immediately and quickly (because the driving voltage is provided by the supply voltage and the stable voltage). Immediately and quickly adjusting the supply voltage to fall within the voltage range means that when switching to only using the supply voltage as the driving voltage, the driving voltage is less likely to exceed the voltage range.

In summary, the various power supply devices, methods and security systems provided by the embodiments of the present invention can achieve the technical effect of preventing hackers from detecting power pins and ground pins to obtain security information. Moreover, compared with the prior art, the various power supply devices, methods and security systems of the embodiments of the present invention can also effectively reduce the size, operation time, power consumption current and circuit area required for the charge storage capacitor. In addition, it is mentioned that the system complexity of the various power supply devices, methods and security systems of the embodiments of the present invention is not high, so it is easy to implement and does not require a huge manufacturing cost. Therefore, the various power supply devices, methods and security systems of the embodiments of the present invention have extremely high practicality and market value.

It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes thereto will be suggested to those skilled in the art and are to be included within the spirit and scope of the present application and the scope of the appended claims.

1, 2: Security system 10: Power supply 12, 20: Power supply device 14, 22: Encryption device 200: Regulated voltage source 202: Switching mode controller 204: Safe power supply device SW1~SW5: Switch 206: Switching switch 208: Surge suppression unit CS: Charge storage capacitor VDIG: Driving voltage VTG-Δ: Lower limit voltage VTG+Δ: Upper limit voltage DVDD, VDD: System voltage CU1~CUn: Switching current unit CR1~CRn: Current source SC1~SCn: Switch R1: Resistor MP1, MP2: PMOS transistor CMP1~CMP3: Comparator C1: Capacitor VLEED: fixed bias T1~T4: interval ENCRP: encryption and decryption working signal CNT1: counter LG1: logic circuit OUT1, OUT2: output signal S102, S104, S106A, S106B: steps

The accompanying drawings are provided to enable a person with ordinary knowledge in the art to which the present invention belongs to further understand the present invention, and are incorporated into and constitute a part of the specification of the present invention. The accompanying drawings show exemplary embodiments of the present invention, and are used together with the specification of the present invention to explain the principles of the present invention.

FIG. 1 is a circuit diagram of a safety system of the prior art.

FIG2 is a circuit diagram of a safety system according to an embodiment of the present invention.

FIG3 is a circuit diagram of a switching mode controller according to an embodiment of the present invention.

FIG4 is a waveform diagram of some signals of the safety system according to an embodiment of the present invention.

FIG5 is a flow chart of a power supply method according to an embodiment of the present invention.

2: Security system

20: Power supply device

22: Encryption and decryption device

200:Stable voltage source

202: Switching mode controller

204: Safe power supply device

206: Switch

208: Ripple suppression unit

VDIG: driving voltage

DVDD, VDD: system voltage

CU1~CUn: Switching current unit

CR1~CRn: current source

SC1~SCn: switch

R1: resistor

MP1, MP2: PMOS transistors

CMP1: Comparator

C1: Capacitor

VLEED: Fixed bias

Claims (10)

A power supply device is used to provide power to an encryption device of a security system, comprising: a safe power supply device, used to provide a supply voltage, wherein the supply voltage can be dynamically adjusted according to the operation of the encryption device; a stable voltage source, used to provide a stable voltage to the encryption device as a driving voltage; and a voltage selection device, electrically connecting the safe power supply device, the stable voltage source and the encryption device; wherein when the encryption device is operating and the When the driving voltage of the encryption device is within the voltage range formed by the upper voltage limit and the lower voltage limit, the voltage selection device only uses the supply voltage as the driving voltage of the encryption device; when the encryption device is not operating and the driving voltage is outside the voltage range, the voltage selection device uses the supply voltage and the stable voltage as the driving voltage of the encryption device, and adjusts the supply voltage until the driving voltage falls into the voltage range. A power supply device as described in claim 1, wherein when the encryption device is operating and the driving voltage is greater than the upper voltage limit, the voltage selection device reduces the supply voltage until the driving voltage is less than the upper voltage limit, and then only the supply voltage is used as the driving voltage of the encryption device; and, when the encryption device is operating and the driving voltage is less than the lower voltage limit, the voltage selection device increases the supply voltage until the driving voltage is greater than the lower voltage limit, and then only the supply voltage is used as the driving voltage of the encryption device. The power supply device as claimed in claim 1, wherein the voltage selection device comprises: a switching mode controller electrically connected to the encryption device and the safe power supply device, used to generate a first switch signal, and to generate a second switch signal according to the first switch signal and the driving voltage of the encryption device, wherein the first switch signal is used to indicate whether the encryption device is operating and whether the driving voltage falls within the voltage range; and a switching switch having a first end, a second end and a control end, wherein the first end is electrically connected to the stable voltage source, the second end is electrically connected to the encryption device, and the control end is electrically connected to the switching mode controller to receive the first switch signal; wherein the supply voltage provided by the safe power supply device is controlled by the second switch signal. A power supply device as described in claim 3, wherein: during a startup period: the switching mode controller makes the first end and the second end conductive, and generates the second switch signal so that the safety power supply device does not provide the supply voltage, so that the encryption device receives the stable voltage as the drive voltage, and after the drive voltage approaches a specific voltage, the startup period ends; and after the startup period ends: when the encryption device is operating and the drive voltage is within the voltage range, the switching mode controller disconnects the first end and the second end, and the encryption device only receives the supply voltage as the drive voltage; when the encryption device is in operation, When the encryption device is in operation and the driving voltage is outside the voltage range, the switching mode controller conducts the first end and the second end, the encryption device receives the supply voltage and the stable voltage as the driving voltage, and the switching mode controller generates the second switch signal so that the safety power supply device adjusts the supply voltage so that the driving voltage falls within the voltage range; and when the encryption device is not in operation, the switching mode controller conducts the first end and the second end, and generates the second switch signal so that the safety power supply device does not provide the supply voltage, so that the encryption device only receives the stable voltage as the driving voltage. A power supply device as described in claim 4, wherein the safety power supply device comprises: a plurality of switching current units, wherein a plurality of ends of the plurality of switching current units are electrically connected to a system voltage, another plurality of ends of the plurality of switching current units are electrically connected to each other and used to output the supply voltage, and the plurality of switching current units are controlled by a plurality of third switch signals, and the second switch signal includes the plurality of third switch signals. A power supply device as described in claim 5, wherein the stable voltage source comprises: a PMOS transistor, wherein the source of the PMOS transistor is electrically connected to the system voltage; a comparator, wherein the output of the comparator is electrically connected to the gate of the PMOS transistor, the negative input of the comparator receives a voltage lower than the target voltage value, and the positive input of the comparator is electrically connected to the first end and the drain of the PMOS transistor; a resistor having two ends electrically connected to the drain of the PMOS transistor and a low voltage, respectively. The power supply device as described in claim 1, wherein the switching mode controller includes: a first comparator having a positive input terminal and a negative input terminal for receiving the upper limit voltage and the driving voltage respectively, wherein the voltage value of the upper limit voltage is the target voltage value of the driving voltage plus the differential voltage value; a second comparator having a positive input terminal and a negative input terminal for receiving the driving voltage and the lower limit voltage respectively, wherein the voltage value of the lower limit voltage is the target voltage value of the driving voltage minus the differential voltage value. The difference voltage value; and a counter having two input terminals electrically connected to the output terminal of the first comparator and the output terminal of the second comparator respectively, wherein the counter counts up or down according to the output signal of the first comparator and the output signal of the second comparator to generate the second switch signal; a logic circuit is used to receive the output signal of the first comparator, the output signal of the second comparator and the encryption and decryption working signal to generate the first switch signal accordingly. A security system, comprising: a power supply device as described in any one of claim items 1 to 7; and the encryption and decryption device. A power supply method is used to provide power to an encryption device of a security system, comprising: when the encryption device is in operation and the driving voltage of the encryption device is greater than an upper limit voltage, using the supply voltage provided by a safety power supply device and the stable voltage provided by a stable voltage source as the driving voltage, and reducing the supply voltage until the driving voltage is less than the upper limit voltage, and then using only the supply voltage as the driving voltage; when the encryption device is in operation and the driving voltage of the encryption device is greater than an upper limit voltage, When the decryption device is operating and the driving voltage is less than the lower limit voltage, the supply voltage and the stable voltage are used as the driving voltage, and the supply voltage is increased until the driving voltage is greater than the lower limit voltage, and then only the supply voltage is used as the driving voltage; and when the encryption and decryption device is operating and the driving voltage is not greater than the upper limit voltage and not less than the lower limit voltage, only the supply voltage is used as the driving voltage. A power supply device is used to provide power to an encryption device of a security system, comprising: a safety power supply device, used to provide a supply voltage according to a system voltage, wherein the supply voltage can be dynamically adjusted according to the operation of the encryption device; a stable voltage source, used to provide a stable voltage to the encryption device as a driving voltage; and a voltage selection device, electrically connecting the safety power supply device, the stable voltage source and the encryption device; wherein when the encryption device is operating and the driving voltage of the encryption device is When the voltage is within the voltage range formed by the upper voltage limit and the lower voltage limit, the voltage selection device only uses the supply voltage as the driving voltage of the encryption device; when the encryption device is operating and the driving voltage is outside the voltage range, the voltage selection device only uses the stable voltage as the driving voltage of the encryption device, and after adjusting the supply voltage until the driving voltage is within the voltage range, only uses the supply voltage as the driving voltage of the encryption device.