Quantum hash value generation system, quantum hash value generation method, and blockchain network

Abstract

A quantum hash value generation system (1) comprises: a quantum state generator (2) configured to generate an input quantum state on the basis of input data composed of input bit strings including a plurality of input bits; a quantum device (4) configured to convert the input quantum state to an output quantum state; a quantum measurement device (5) configured to measure the output quantum state to acquire measured values of the output quantum state; a measured value analysis unit (320) configured to calculate a statistical index values for each of the measured values on the basis of the probability distribution of each measured value; and a quantum hash value generation unit (340) configured to generate a quantum hash value of the input data on the basis of the statistical index value for each of the measured values.

Description

Quantum hash value generation system, quantum hash value generation method, and blockchain network

[0001] The present disclosure relates to a quantum hash value generation system, a quantum hash value generation method, and a blockchain network.

[0002] Since the publication in 2008 of a white paper (Non-Patent Document 1) on a P2P (Peer-to-Peer) electronic cash system that solved the problem of duplicate payments, blockchain networks, led by the Bitcoin network, have continued to grow at an astonishing rate.

[0003] The Bitcoin network uses Proof of Work (PoW) as a consensus mechanism when adding a new block to the blockchain to ensure the reliability of the network. PoW requires searching for a nonce value that results in a block header hash value smaller than a specific value. The Bitcoin network also uses Secure Hash Algorithm (SHA)-256 as the hash function (hash algorithm) used to calculate the hash value of the block header.

[0004] Satoshi Nakamoto (2008), “Bitcoin: A Peer-to-Peer Electronic Cash System”, Bitcoin. org.

[0005] However, with the development of quantum computers, which are currently attracting attention, it is predicted that in the future, the original data of a block header may be calculated from a hash value based on the hash function SHA-256 used in the Bitcoin network. In this regard, it is extremely difficult for classical computers such as ASICs and FPGAs to calculate the original data from a hash value based on the hash function SHA-256 due to the enormous amount of calculation required (in other words, the cryptographic one-way nature of SHA-256 is guaranteed). On the other hand, with future advances in quantum computers, the hash algorithms currently used in PoW (e.g., SHA-256, ETHash, KawPow, kHeavyHash, etc.) may no longer be cryptographic one-way functions. As a result, quantum computers could significantly undermine the reliability of blockchain networks (typically the Bitcoin network) that currently rely on PoW.

[0006] Therefore, in light of the above-mentioned problems with blockchain networks that use PoW, such as the Bitcoin network, there is room for new consideration of new hash functions that differ from conventional hash functions such as SHA-256, and blockchain networks that utilize these functions.

[0007] In view of the above, the present disclosure aims to provide a new hash function that can replace conventional hash functions such as SHA-256, in particular a quantum hash function with quantum resistance, and a blockchain network that uses the same. More specifically, the present disclosure aims to provide a quantum hash value generation system, a quantum hash value generation method, and a blockchain network that utilizes the quantum hash value generation system.

[0008] A quantum hash value generation system according to one aspect of the present disclosure includes a quantum state generator configured to generate an input quantum state based on input data configured from an input bit string including a plurality of input bits; a quantum device configured to convert the input quantum state into an output quantum state; a quantum measurement device configured to obtain each measurement value of the output quantum state by measuring the output quantum state; a measurement value analysis unit configured to calculate a statistical index value of each measurement value based on a probability distribution of each measurement value; and a quantum hash value generation unit configured to generate a quantum hash value of the input data based on the statistical index value of each measurement value.

[0009] According to the above configuration, after an input quantum state is generated based on input data, the input quantum state is converted into an output quantum state by the quantum device. After that, a measurement value of the output quantum state is obtained by the quantum measuring device, and a statistical index value of the measurement value is calculated. Finally, a quantum hash value of the input data is generated based on the statistical index value of the measurement value. In this way, in the process of generating the quantum hash value, the input quantum state is converted into an output quantum state by the quantum device, and the measurement value of the output quantum state is obtained by the quantum measuring device, so it is possible to provide a quantum hash value generation system that is quantum-resistant.

[0010] The statistical index value may be an expected value of each of the measurement values.

[0011] The quantum hash value generator may also be configured to generate the quantum hash value based on a comparison between a statistical index value of each of the measurement values ​​and a threshold value set for each of the measurement values.

[0012] The quantum hash value may be configured by an output bit string including a plurality of output bits. When a predetermined statistical index value among the plurality of statistical index values ​​is smaller than a predetermined threshold, the quantum hash value generator may set a value of the output bit corresponding to the predetermined statistical index value to either 0 or 1, and when the predetermined statistical index value is equal to or greater than the predetermined threshold, set a value of the output bit corresponding to the predetermined statistical index value to the other of 0 or 1.

[0013] Furthermore, the process of generating the input quantum state, the process of converting the input quantum state to the output quantum state, and the process of obtaining each measurement value of the output quantum state may be performed repeatedly.

[0014] A quantum hash value generation method according to one aspect of the present disclosure includes a first generation step of generating an input quantum state based on input data configured with an input bit string including a plurality of input bits, a conversion step of converting the input quantum state into an output quantum state, an acquisition step of measuring the output quantum state to obtain each measurement value of the output quantum state, a calculation step of calculating a statistical index value of each measurement value based on a probability distribution of each measurement value, and a second generation step of generating a quantum hash value of the input data based on the statistical index value of each measurement value.

[0015] According to the above method, an input quantum state is converted into an output quantum state by a quantum device, and a measurement value of the output quantum state is obtained by a quantum measuring device, thereby providing a quantum hash value generation method that is quantum-resistant.

[0016] The statistical index value may be an expected value of each of the measurement values.

[0017] The second generating step may also include generating the quantum hash value based on a comparison between a statistical index value of each of the measurement values ​​and a threshold value set for each of the measurement values.

[0018] The quantum hash value may be configured by an output bit string including a plurality of output bits. The second generating step may include a step of setting a value of an output bit corresponding to a predetermined statistical index value to either 0 or 1 when a predetermined statistical index value among the plurality of statistical index values ​​is smaller than a predetermined threshold, and a step of setting a value of an output bit corresponding to the predetermined statistical index value to the other of 0 or 1 when the predetermined statistical index value is equal to or greater than the predetermined threshold.

[0019] The first generating step, the converting step, and the obtaining step may be repeatedly performed.

[0020] According to one aspect of the present disclosure, a blockchain network is configured with multiple nodes, each of which stores a blockchain. The blockchain network calculates a quantum hash value of a new block using the quantum hash value generation method, and adds the new block to the blockchain if the calculated quantum hash value satisfies a predetermined condition. In this way, a quantum-resistant blockchain network can be provided.

[0021] According to the present disclosure, it is possible to provide a quantum hash value generation system, a quantum hash value generation method, and a blockchain network that are quantum resistant.

[0022] FIG. 1 is a diagram showing a quantum hash value generation system according to an embodiment of the present disclosure (hereinafter referred to as the present embodiment). FIG. 2 is a diagram showing an example of the hardware configuration of a processing device. FIG. 3 is a flowchart for explaining the process of generating a quantum hash value. FIG. 4 is a flowchart specifically explaining the process of generating a quantum hash value from each measurement value of an output quantum state. FIG. 5 is a diagram showing an example of a blockchain network configured by a plurality of nodes each having a quantum hash value generation system. FIG. 6 is a diagram showing an example of a blockchain network configured by a plurality of nodes each communicatively connected to a quantum hash value generation system. FIG. 7 is a flowchart for explaining the process of generating a new block using a quantum hash value generation method.

[0023] A quantum hash value generation system 1 according to this embodiment will be described below with reference to the drawings. FIG. 1 is a diagram showing the quantum hash value generation system 1 according to this embodiment. As shown in FIG. 1, the quantum hash value generation system 1 includes a quantum state generator 2, a quantum device 4, a quantum measurement device 5, and a processing device 3. In this embodiment, the hardware configurations of the quantum state generator 2, the quantum device 4, and the quantum measurement device 5 are not limited to a specific type of hardware configuration. In particular, it should be noted that the hardware configurations of the quantum state generator 2 and the quantum measurement device 5 connected to the quantum device 4 are appropriately changed depending on the type of hardware configuration of the quantum device 4 (e.g., an optical quantum computer, a quantum computer based on quantum gates, an ion / atom trap quantum computer, a superconducting quantum computer, etc.).

[0024] The quantum state generator 2 is configured to generate an input quantum state |input> based on input data x transmitted from the calculation processing device 3. For example, if the quantum device 4 is an optical quantum computer, the quantum state generator 2 may be an optical parametric oscillator (OPO) configured to output pulsed light. The input data x is original data to be calculated by the quantum hash function (quantum hash algorithm) realized by the quantum hash value generation system 1, and may be, for example, data of a block header of a blockchain 8 (see FIG. 5). The block header includes, for example, a block version number, a hash value of the previous block, a Mercury hash value, a timestamp, a target value (difficulty), a nonce value, etc.

[0025] The quantum device 4 is configured to convert the input quantum state |input> output from the quantum state generator 2 into an output quantum state |output>. The quantum device 4 is connected to the quantum state generator 2 via multiple input transmission paths 110. The quantum device 4 is, for example, a quantum computer. If the quantum device 4 is a quantum computer based on quantum gates, the conversion from the input quantum state |input> to the output quantum state |output> may be described as a set of quantum gates. The quantum device 4 may also be an optical quantum computer realized by a lightwave circuit including optical elements such as beam splitters, phase shifters, and mirrors, and optical fibers. Furthermore, the quantum device 4 may be an ion / atom trap quantum computer. In this case, the conversion from the input quantum state |input> to the output quantum state |output> is realized by manipulating individual quantum states using a laser. The quantum device 4 may also be a superconducting quantum computer. In this case, the transformation from the quantum state |input> to the output quantum state |output> is realized by manipulating a group of Josephson junctions in the superconducting state with microwave pulses.

[0026] In the quantum hash value generation system 1, the conversion from the input quantum state |input> to the output quantum state |output> is necessary to achieve quantum supremacy. That is, while this conversion can be easily calculated in polynomial time by the quantum device 4, calculating this conversion by a classical computer requires quantum simulation, which requires a large amount of memory and a larger amount of calculation than a quantum computer.

[0027] The quantum measuring device 5 is configured to measure the output quantum state |output> output from the quantum device 4, thereby obtaining each measurement value m of the output quantum state |output>. The quantum measuring device 5 is connected to the quantum device 4 via multiple output transmission paths 120. The quantum measuring device 5 includes multiple quantum detection units 50 (N quantum detection units 50 in this example) arranged in parallel. Each quantum detection unit 50 is configured to detect a measurement value of a measurand output from a corresponding one of the multiple output transmission paths 120 connected to the output side of the quantum device 4. When the quantum device 4 is an optical quantum computer, the quantum detection unit 50 may be a photon detection unit that detects the number of photons (an example of a measurement value) output from an optical fiber (an example of a transmission path) connected to the output side of the quantum device 4. When the quantum device 4 is a superconducting bit quantum computer, the quantum detection unit 50 may use signal processing of the frequency shift of a resonator connected to each output transmission path 120 on the output side of the quantum device 4.

[0028] The Born rule and uncertainty relation of quantum mechanics guarantee that the quantum hash function (quantum hash algorithm) realized by the quantum hash value generation system 1 cannot be calculated in reverse. According to the Born rule, a probability distribution of output bits is given by measuring the output quantum state. Note that, according to the Born rule, the output quantum state changes after measurement, so it is not possible to revert from the output quantum state after measurement to the output quantum state before measurement. Therefore, the probability distribution of the measurement results is obtained by multiple measurements. Furthermore, because the uncertainty relation imposes a limit on the maximum amount of information that can be obtained simultaneously, the output quantum state generally cannot be determined from the probability distribution of the measurement results. As a result of these quantum mechanical consequences, the measurement results contain exponentially less information than the output quantum state, making it impossible to completely estimate the output quantum state from the measurement results. Because the measurement results of the output quantum state have variance due to the uncertainty relation, in this embodiment, the output quantum state is repeatedly measured. In this embodiment, the output quantum state is repeatedly measured by a single quantum state generator 2, quantum device 4, and quantum measurement device 5, but multiple quantum state generators 2, quantum devices 4, and quantum measurement devices 5 may be provided in the quantum hash value generation system 1 in order to process the measurement of the output quantum state in parallel.

[0029] The processing device 3 has an input data sending unit 310, a measurement value receiving unit 330, a measurement value analyzing unit 320, and a quantum hash value generating unit 340. These are functionally realized by the control unit 30 (see FIG. 2 ) of the processing device 3. The input data sending unit 310 is configured to send input data x to the quantum state generator 2. The measurement value receiving unit 330 is configured to receive each measurement value m of the output quantum state from the quantum measuring device 5.

[0030] The measurement value analysis unit 320 is configured to analyze each measurement value of the output quantum state after receiving it from the measurement value receiving unit 330. In particular, the measurement value analysis unit 320 is configured to calculate a probability distribution of each measurement value and to calculate an expectation value (such as a simple expectation value or a three-body correlation expectation value) of each measurement value based on the probability distribution of each measurement value. The expectation value of a measurement value is an example of a statistical index value of a measurement value.

[0031] The quantum hash value generator 340 is configured to receive the expected values ​​of each measurement value from the measurement value analyzer 320 and generate a quantum hash value y of the input data x based on the expected values ​​of each measurement value.

[0032] Next, an example of the hardware configuration of the processing device 3, which is a classical computer, will be described below with reference to Fig. 2. Fig. 2 is a diagram showing an example of the hardware configuration of the processing device 3. As shown in Fig. 2, the processing device 3 includes a control unit 30, a storage device 31, an input / output interface 32, a communication unit 33, an input operation unit 34, and a display unit 35. These elements are connected to a communication bus 36.

[0033] The control unit 30 includes a memory and a processor. The memory is configured to store computer-readable instructions (programs). For example, the memory may include a ROM (Read Only Memory) in which various programs are stored, and a RAM (Random Access Memory) having multiple work areas in which various programs executed by the processor are stored. The processor may include at least one of a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a GPU (Graphics Processing Unit), an FPGA (Field-Programmable Gate Array), and an ASIC (Application-Specific Integrated Circuit). The CPU may be configured with multiple CPU cores. The GPU may be configured with multiple GPU cores. The processor may be configured to load a specified program from various programs stored in the storage device 31 or ROM onto the RAM and execute various processes in cooperation with the RAM.

[0034] The storage device 31 is a storage device (storage) such as a hard disk drive (HDD), a solid state drive (SSD), or a flash memory, and is configured to store programs and various data. The input / output interface 32 is an interface that enables connection between an external device and the arithmetic processing device 3, and includes an interface conforming to a predetermined communication standard such as the USB standard or the HDMI (registered trademark) standard. The communication unit 33 includes, for example, a wired communication module and / or a wireless communication module for communicating with an external device connected to a communication network such as the Internet. The input operation unit 34 is, for example, a touch panel, a touch pen, a mouse, and / or a keyboard. The input operation unit 34 is configured to accept input operations by an operator operating the arithmetic processing device 3 and to generate operation signals corresponding to the input operations. The display unit 35 is, for example, configured to include a video display such as a liquid crystal display or an organic electroluminescence (EL) display, and a video display circuit that drives and controls the video display.

[0035] (Flow of quantum hash value calculation process) Next, the flow of quantum hash value generation process will be described below with reference to FIG. 3. FIG. 3 is a flowchart for explaining the quantum hash value generation process. As shown in FIG. 3, in step S1, the calculation processing device 3 acquires N-bit input data x. For example, the calculation processing device 3 provided in the quantum hash value generation system 1 may receive the input data x from a predetermined node 10a constituting the blockchain network 100a (see FIG. 6). Here, the input data x is N (N is a natural number) input bits x １ , x ２ , x ３ , …x ＮThe input data x may be data of a block header of a blockchain (such as a block version number, a hash value of the previous block, a hash value of a mercroot, a timestamp, a target value, or a nonce value). In this case, the bit length of the input data x corresponds to the fixed bit length of the block header. Therefore, the bit length of the input data x corresponding to the data of the block header may be fixed at N bits.

[0036] In addition, if the data length (M bits) of the block header is different from the data length (N bits) of the quantum hash value that is finally generated (i.e., M≠N), the M-bit block header data may be first converted into N-bit input data x through a predetermined function.

[0037] Furthermore, the bit length of the input data x may be variable. In this case, the input data x may be temporarily compressed to N bits using an existing hash function based on SHA or the like before being input to the quantum state generator 2. The compressed N-bit input data x may then be input to the quantum state generator 2. In this case, it becomes possible to generate an N-bit quantum hash value y from input data x of any bit length.

[0038] Next, in step S2, the quantum state generator 2 receives input data x from the input data transmission unit 310 and generates an input quantum state |input> based on the received input data x. Here, each of the multiple input bits included in the input data x corresponds one-to-one to one of the multiple input quantum bits included in the input quantum state |input>. The input quantum state |input> is composed of an input quantum bit string including multiple input quantum bits. For example, the input bit x ｎ is 0, then the input bit x ｎ The quantum state of the qubit corresponding to input bit x is |0>. ｎ is 1, then the input bit x ｎ The quantum state of the quantum bit corresponding to is |1>.

[0039] In step S3, the quantum device 4 converts the input quantum state |input> output from the quantum state generator 2 into an output quantum state |output>. As described above, the quantum device 4 may be an optical quantum computer, an ion / atom trap quantum computer, or a superconducting quantum computer. Next, in step S4, the quantum measuring device 5 measures the output quantum state output from the quantum device 4 to obtain each measurement value m of the output quantum state. １ , m ２ , m ３ ,... m Ｎ When the quantum device 4 is an optical quantum computer, the measurement value m is, for example, the number of photons. In particular, each of the N quantum detectors 50 provided in the quantum measuring device 5 detects the measurement value m of the measurand output from a corresponding one of the N output transmission paths 120. For example, the quantum detector 50 arranged at the nth position detects the measurement value m of the measurand output from the nth output transmission path 120. ｎ (In other words, the measurement value m of the output quantum state ｎ ) are obtained by the N quantum detectors 50. Ｎ is measured. The number of input transmission paths 110 and output transmission paths 120 provided in the quantum hash value generation system 1 is not limited to N.

[0040] Thereafter, the measurement value receiving unit 330 receives each measurement value m １ ~m Ｎ from the quantum measuring device 5. Next, the calculation processing device 3 determines whether the number of measurements of the measurement value has reached a predetermined number (step S5). If the number of measurements has not reached the predetermined number (NO in step S5), the processes of steps S2 to S4 are repeatedly executed until the number of measurements reaches the predetermined number. On the other hand, if the number of measurements has reached the predetermined number (YES in step S5), the measurement value analysis unit 320 calculates the measurement value m of each measurement value of the output quantum state. １ ~m Ｎ Based on the probability distribution Prob of each measurement value m １ ~m Ｎ Then, the quantum hash value generator 340 calculates the expected value (an example of a statistical index value) of each measurement value m１ ~m Ｎ Based on the expected value of １ , y ２ , y ３ ,... .y Ｎ ) is generated (step S7).

[0041] In the determination process of step S5, it is determined whether the number of measurements of the measurement value has reached a predetermined number, but the determination process of step S5 is not limited to this. In this regard, the calculation processing device 3 may determine whether the measurement error has become small in step S5. In this case, the processes of steps S2 to S4 may be repeatedly executed until the measurement error becomes equal to or less than the threshold value.

[0042] (Specific Description of Quantum Hash Value Computation Process) Next, the process of generating a quantum hash value from each measurement value of the output quantum state (i.e., the processes of steps S6 and S7) will be specifically described below with reference to Fig. 4. Fig. 4 is a flowchart specifically describing the process of generating a quantum hash value from each measurement value of the output quantum state.

[0043] As shown in FIG. 4, in step S10, the measurement value analysis unit 320 calculates the measurement value m of the first output of the output quantum state |output>. １ The measured value m of the Nth output from Ｎ The joint probability distribution Prob(m １ , m ２ , m ３ ,... m Ｎ Here, the measured value m of the nth (n = 1 to N) output of the output quantum state |output> is calculated. ｎ is the measured value m of the measured quantity output from the nth output transmission line 120 ｎ and is acquired by the n-th quantum detector 50. ｎ The number of measurements corresponds to the number of measurements of the measurement value (see step S5 in FIG. 3). For example, if the number of measurements of the measurement value is 10,000, each measurement value m ｎ The number of measurements m ｎ Based on the joint probability distribution Prob(m １ , m２ , m ３ ,... m Ｎ ) is calculated.

[0044] Next, in step S11, a plurality of measurement values ​​m of the first output of the output quantum state |output> are １ In the quantum hash value calculation process, the multiple measured values ​​m of the first output are １ Multiple measurements m of the Nth output from Ｎ That is, as indicated by the determination condition in step S17, the processes in steps S12 to S16 are repeated until n=N.

[0045] In step S12, the measurement value analysis unit 320 calculates the joint probability distribution Prob(m １ , m ２ , m ３ ,... m Ｎ ) based on a plurality of measurements m of the nth output ｎ The probability distribution of Prob(m ｎ ) is calculated. ｎ ) is a joint probability distribution that combines the probabilities that a measurand will take a certain measurement. For example, ｎ can take three values: 0, 1, and 2, the probability distribution Prob(m ｎ ) indicate the probability of the value 0, the probability of the value 1, and the probability of the value 2, respectively.

[0046] Next, the measurement value analyzer 320 calculates the measurement value m ｎ The probability distribution of Prob(m ｎ ) based on a plurality of measurements m ｎ Expected value of < m ｎ In this embodiment, a simple expected value of a plurality of measurement values ​​is used as an example of a statistical index value, but instead of the simple expected value, an expected value, median, mean, mode, maximum value, minimum value, etc. of a three-body correlation of a plurality of measurement values ​​may be used.

[0047] In step S14, the quantum hash value generation unit 340 calculates the expected value calculated by the measurement value analysis unit 320 as follows: ｎ> is the measured value m ｎ The threshold δ set for ｎ Determine whether the expected value is greater than or equal to m ｎ > is the threshold δ ｎ If the result is YES in step S14, the quantum hash value generation unit 340 calculates the n-th output bit y ｎ is set to 1 (step S15). On the other hand, if the expected value < m ｎ > is the threshold δ ｎ (NO in step S14), the quantum hash value generation unit 340 ｎ is set to 0 (step S16). In this way, through the processing of steps S12 to S16, the n-th measurement values ​​m of the output quantum state are ｎ The output bit y corresponding to ｎ That is, the input bit x ｎ → input bit x ｎ Input quantum state corresponding to input bit x ｎ The output quantum state (measurement m ｎ ) → output bit y ｎ The calculation process is performed in the following order.

[0048] Next, if n=N is not satisfied (NO in step S17), n is set to n+1 (step S18), and the processes of steps S12 to S16 are executed again. In this way, the processes of steps S12 to S16 are repeatedly executed until n=N is satisfied, and the measurement value m １ ~m Ｎ Expected value of < m １ >~<m Ｎ > based on the first output bit y １ to the Nth output bit y Ｎ is determined.

[0049] On the other hand, if n=N (YES in step S17), the quantum hash value generation unit 340 generates N output bits y １ , y ２ , y ３ ,... .y Ｎ(Step S19). In this way, it is possible to generate a quantum hash value y of the input data x by using the quantum hash value generation system 1. The quantum hash value generation system 1 functions as a quantum hash function that generates a quantum hash value y of the input data x.

[0050] According to this embodiment, after an input quantum state |input> is generated based on input data x, the quantum device 4 converts the input quantum state |input> into an output quantum state |output>. Then, the quantum measuring device 5 measures each measurement value m of the output quantum state |output>. １ ~m Ｎ After the measurement m １ ~m Ｎ Expected value of < m １ >~<m Ｎ Finally, the expected value <m １ >~<m Ｎ Quantum hash value y (y １ , y ２ , y ３ ,... .y Ｎ In this way, in the process of generating the quantum hash value y, the quantum device 4 converts the input quantum state |input> into the output quantum state |output>, and the quantum measuring device 5 converts the measurement value m １ ~m Ｎ is obtained, it is possible to provide a quantum hash value generation system 1 (a new quantum hash algorithm that replaces conventional hash algorithms such as SHA-256) that is resistant to attacks by quantum computers (quantum resistance). In this respect, in this embodiment, the uncertainty principle of quantum mechanics guarantees that the quantum hash function realized by the quantum hash value generation system 1 cannot be calculated in the reverse direction (in other words, it is guaranteed that the input data x cannot be calculated from the quantum hash value y).

[0051] In this embodiment, each measurement value m ｎ Expected value of < m ｎ > and each measurement value m ｎThe threshold δ set for ｎ and output bits y that constitute the quantum hash value y based on the comparison between ｎ However, this embodiment is not limited to this. For example, each measurement value m ｎ Based on the value obtained by inputting a predetermined function to the statistical index value of ｎ may be determined.

[0052] In this embodiment, the expected value < m ｎ > is the threshold δ ｎ If greater than or equal to y, output bit y ｎ is set to 1, while the expected value < m ｎ > is the threshold δ ｎ output bit y if ｎ is set to 0, but this embodiment is not limited to this. In this respect, the expected value < m ｎ > is the threshold δ ｎ If greater than or equal to y, output bit y ｎ is set to 0, while the expected value < m ｎ > is the threshold δ ｎ output bit y if ｎ may be set to 1.

[0053] Furthermore, in this embodiment, the joint probability distribution Prob(m １ , m ２ , m ３ ,... m Ｎ ) based on each measurement m ｎ The probability distribution of Prob(m ｎ ) is calculated, but the present embodiment is not limited to this. １ , m ２ , m ３ ,... m Ｎ ), the probability distribution Prob(m ｎ , m ｌ , m ｋ ) may be calculated (where n, l, and k are different natural numbers). １ , m ２ , m ３ ,... mＮ ), a probability distribution Prob of L-body correlations (L is a natural number) may be calculated.

[0054] For example, the probability distribution of the three-body correlation Prob(m ｎ , m ｌ , m ｋ ) is calculated, the probability distribution Prob(m ｎ , m ｌ , m ｋ ) based on the measured value m ｎ , m ｌ , m ｋ The expectation value of the three-body correlation of < m ｎ，ｌ，ｋ > is calculated. Then, the expected value of the calculated three-body correlation <m ｎ，ｌ，ｋ > is the measured value m ｎ , m ｌ , m ｋ The threshold δ set for the combination of ｎ，ｌ，ｋ It is determined whether the expected value is greater than or equal to m ｎ，ｌ，ｋ > is the threshold δ ｎ，ｌ，ｋ If the expected value is greater than or equal to m, the quantum hash value generation unit 340 sets the predetermined-th output bit constituting the quantum hash value y to 1. On the other hand, if the expected value is less than m ｎ，ｌ，ｋ > is the threshold δ ｎ，ｌ，ｋ If the quantum hash value y is smaller than 0, the quantum hash value generation unit 340 sets the predetermined-th output bit that constitutes the quantum hash value y to 0.

[0055] In this embodiment, an N-bit quantum hash value y is generated from N-bit input data x, but the data length of the input data x and the data length of the quantum hash value y do not have to be the same. That is, a K-bit quantum hash value y may be generated from N-bit input data x (N≠K). In particular, the probability distribution Prob(m ｎ , m ｌ , m ｋ ) based on the measured value m ｎ , m ｌ , m ｋ The expectation value of the three-body correlation of < m ｎ，ｌ，ｋ When the above equation is calculated, it becomes possible to generate a K-bit quantum hash value y from N-bit input data x.

[0056] (Blockchain network using quantum hash value generation method) Next, a blockchain network 100 using a quantum hash value generation method will be described below with reference to Fig. 5 and Fig. 7. Fig. 5 is a diagram showing an example of a blockchain network 100 configured with multiple nodes 10, each having a quantum hash value generation system 1. Fig. 7 is a flowchart for explaining the process of generating a new block using the quantum hash value generation method.

[0057] As shown in Fig. 5, the blockchain network 100 is a P2P network (distributed network) made up of multiple nodes 10. Each node 10 stores a blockchain 8 in which multiple transactions are recorded. The blockchain 8 is a type of distributed ledger technology (DLT), and the blockchains 8 stored by each node 10 hold the same ledger information (transaction information).

[0058] The blockchain 8 is composed of multiple blocks. Each block is linked to the blocks generated before and after it. Specifically, each block is associated with the block generated immediately before and after it via the hash value of the block header. Therefore, in the blockchain 8, if some transactions are tampered with, the hash value of the block header is changed, and each block is linked in a chain reaction by the hash values ​​of the block headers of the previous and next blocks, making it extremely difficult to tamper with the data of each block (especially the transaction information within each block).

[0059] In the blockchain network 100 shown in FIG. 5, each node 10 is equipped with a quantum hash value generation system 1 for calculating a hash value of a block header. Each node 10 is able to calculate a quantum hash value of a block header through the quantum hash value generation system 1. In the blockchain network 100 using a quantum hash function, PoW is adopted as the consensus mechanism when adding a new block to the blockchain 8 to ensure the reliability of the network. Using the quantum hash value generation system 1, each node 10 functions as a miner that searches for a nonce value such that the quantum hash value of the block header satisfies predetermined conditions.

[0060] In the blockchain network 100, each node 10 is equipped with a quantum hash value generation system 1. On the other hand, as shown in Fig. 6, each node 10a constituting the blockchain network 100a may not be equipped with the quantum hash value generation system 1. In this case, each node 10a is communicatively connected to the quantum hash value generation system 1 via a communication network (not shown). That is, each node 10a may search for a quantum hash value of a block header that satisfies a predetermined condition by using the quantum hash value generation system 1 on the cloud.

[0061] (New Block Generation Process Using Quantum Hash Value) As shown in FIG. 7 , in step S20, a predetermined node 10 (miner) on the blockchain network 100 inputs a nonce value into the block header to generate a new block. Next, the predetermined node 10 calculates a quantum hash value of the block header using the quantum hash value generation system 1 (step S21). Here, the data in the block header may include the block version number, the hash value of the previous block, the Mercury hash value, a timestamp, a target value, a nonce value, etc. The block header data is input to the quantum hash value generation system 1 as input data x. After receiving the input data x, the quantum hash value generation system 1 generates a quantum hash value y of the input data x (block header data) through the quantum hash value calculation process shown in FIG. 3 .

[0062] In step S22, a predetermined node 10 determines whether the quantum hash value of the block header generated through the quantum hash value generation system 1 satisfies a predetermined condition. Here, the predetermined condition associated with the quantum hash value y is a condition for generating a new block, and may indicate that the quantum hash value of the block header is equal to or less than a predetermined value (in other words, that the most significant m digits (m is a natural number) of the quantum hash value are 0).

[0063] If the quantum hash value of the block header does not satisfy the predetermined condition (NO in step S22), the processes of steps S20 and S21 are repeated until the predetermined condition of step S22 is satisfied. On the other hand, if the quantum hash value of the block header satisfies the predetermined condition (YES in step S22), the predetermined node 10 broadcasts the success of block generation to the other nodes 10 on the blockchain network 100 (step S23). The other nodes 10 verify and approve the new block generated by the predetermined node 10, and then add the new block to the blockchain 8 (step S24).

[0064] In the blockchain network 100 according to this embodiment, the quantum hash value of the block header is generated by the quantum hash value generation system 1 (particularly, a new quantum hash algorithm), making it possible to provide a quantum-resistant blockchain network. In particular, unlike conventional blockchain networks such as the Bitcoin network that employs SHA-256, it is possible to reliably prevent a situation in which the original data of the block header is calculated from the hash value through a quantum attack, making it possible to provide a highly reliable blockchain network 100 that employs PoW as the consensus mechanism.

[0065] Although the embodiments of the present invention have been described above, the technical scope of the present invention should not be construed as being limited by the description of the present embodiments. The present embodiments are merely examples, and it will be understood by those skilled in the art that various modifications of the embodiments are possible within the scope of the invention described in the claims. The technical scope of the present invention should be determined based on the scope of the invention described in the claims and its equivalents.

[0066] This application appropriately incorporates by reference the contents disclosed in Japanese Patent Application No. 2024-097768 filed on June 17, 2024.

Claims

1. A quantum hash value generation system comprising: a quantum state generator configured to generate an input quantum state based on input data configured from an input bit string including a plurality of input bits; a quantum device configured to convert the input quantum state into an output quantum state; a quantum measurement device configured to obtain each measurement value of the output quantum state by measuring the output quantum state; a measurement value analysis unit configured to calculate a statistical index value of each measurement value based on a probability distribution of each measurement value; and a quantum hash value generation unit configured to generate a quantum hash value of the input data based on the statistical index value of each measurement value.

2. The quantum hash value generation system according to claim 1, wherein the statistical index value is an expected value of each of the measured values.

3. The quantum hash value generation system according to claim 1 or 2, wherein the quantum hash value generation unit is configured to generate the quantum hash value based on a comparison between a statistical index value of each of the measurement values ​​and a threshold value set for each of the measurement values.

4. The quantum hash value generation system of claim 3, wherein the quantum hash value is composed of an output bit string including a plurality of output bits, and the quantum hash value generation unit sets the value of the output bit corresponding to a predetermined statistical index value to either 0 or 1 when a predetermined statistical index value among the plurality of statistical index values ​​is smaller than a predetermined threshold, and sets the value of the output bit corresponding to the predetermined statistical index value to the other of 0 or 1 when the predetermined statistical index value is equal to or greater than the predetermined threshold.

5. The quantum hash value generation system according to claim 1, wherein the process of generating the input quantum state, the process of converting the input quantum state into the output quantum state, and the process of obtaining each measurement value of the output quantum state are repeatedly executed.

6. A quantum hash value generation method comprising: a first generation step of generating an input quantum state based on input data configured from an input bit string including a plurality of input bits; a conversion step of converting the input quantum state into an output quantum state; an acquisition step of measuring the output quantum state to obtain each measurement value of the output quantum state; a calculation step of calculating a statistical index value of each measurement value based on a probability distribution of each measurement value; and a second generation step of generating a quantum hash value of the input data based on the statistical index value of each measurement value.

7. The quantum hash value generation method according to claim 6, wherein the statistical index value is an expected value of each of the measured values.

8. A quantum hash value generation method as described in claim 6, wherein the second generation step includes a step of generating the quantum hash value based on a comparison between a statistical index value of each of the measurement values ​​and a threshold value set for each of the measurement values.

9. The quantum hash value generation method of claim 8, wherein the quantum hash value is composed of an output bit string including a plurality of output bits, and the second generation step includes: a step of setting the value of the output bit corresponding to a predetermined statistical index value to either 0 or 1 when a predetermined statistical index value among the plurality of statistical index values ​​is smaller than a predetermined threshold; and a step of setting the value of the output bit corresponding to the predetermined statistical index value to the other of 0 or 1 when the predetermined statistical index value is equal to or greater than the predetermined threshold.

10. The quantum hash value generation method according to claim 6, wherein the first generation step, the conversion step, and the acquisition step are repeatedly executed.

11. A blockchain network made up of multiple nodes, each of which stores a blockchain, wherein the blockchain network calculates a quantum hash value of a new block using the quantum hash value generation method described in any one of claims 6 to 10, and adds the new block to the blockchain if the calculated quantum hash value satisfies a predetermined condition.

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