Mobile communication terminal quantum key distribution method and system

Abstract

The invention discloses a quantum key distribution method and system for a mobile communication terminal, and belongs to the field of secret communication.The quantum key distribution method for the mobile communication terminal comprises the following steps that a quantum optical signal is prepared through a quantum signal sending end, and the quantum optical signal comprises the bit value of a first random bit sequence and a selected preparation base; a quantum optical signal is received through a quantum signal receiving end, a measurement base is randomly selected, and if the measurement base is the same as a preparation base, compared with the prior art, the method has the beneficial effects that a third key is converted through a universal hash function, and as long as the minimum entropy of an initial key meets the security requirement, the security requirement is met; hash output can ensure that the guess probability of an attacker to a final key is reduced in an exponential level, and the information amount of the key owned by the attacker is compressed to a negligible level, so that the reliability of the finally obtained fourth key is high; by setting quantum optical signals with different intensities, whether eavesdropping exists is verified, and the possibility of key leakage is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of confidential communications, and in particular relates to a quantum key distribution method and system for mobile communication terminals. Background Art

[0002] The quantum key distribution protocol relies on classical channels to transmit basis comparison, error correction and other non-key information.

[0003] In existing quantum key distribution protocols, when the error rate (Quantum Bit Error Rate, QBER) of a selected bit is verified to be below a preset security threshold, it can be used as a key through error correction. However, if the QBER does not exceed the threshold, an eavesdropper may still be able to obtain a small amount of key information through the quantum channel (for example, through a lossless attack). The error correction process may also cause a small amount of key information to be leaked, which is not secure enough and needs improvement. Summary of the Invention

[0004] Based on this, it is necessary to provide a quantum key distribution method and system for mobile communication terminals to address the above problems.

[0005] The embodiment of the present invention is implemented as follows: a method for quantum key distribution of a mobile communication terminal, comprising the following steps:

[0006] A quantum light signal is prepared by a quantum signal transmitter. The quantum light signal includes the bit value of the first random bit sequence and a selected preparation basis. The quantum light signal is received by a quantum signal receiver, and a measurement basis is randomly selected. If the measurement basis and the preparation basis are the same, the bit value sent by the quantum signal transmitter at that position is obtained.

[0007] The bit positions of the quantum signal transmitter and the quantum signal receiver using the same basis are retained as the first key. A portion of the bits of the first key are selected, and the error rate of the selected bits is verified. If the error rate is lower than a preset security threshold, the remaining first keys that were not selected are used as the second key.

[0008] The inconsistency of the second keys of the quantum signal sending end and the quantum signal receiving end is corrected to obtain a third key, and the third key is converted through a universal hash function to obtain a shorter but more secure fourth key, which is used as the key for information encryption.

[0009] In one embodiment, the present invention provides a method for quantum key distribution at a mobile communication terminal, wherein a quantum light signal is prepared by a quantum signal transmitting end, the quantum light signal includes the bit value of a first random bit sequence and a selected preparation basis, the quantum light signal is received by a quantum signal receiving end, and a measurement basis is randomly selected. If the measurement basis and the preparation basis are the same, the step of obtaining the bit value sent by the quantum signal transmitting end at the position specifically includes:

[0010] Controlling the quantum signal transmitter to generate a first random bit sequence and a second random bit sequence, wherein the second random bit sequence is used to select a preparation basis (H / V basis or D / A basis);

[0011] Based on the bit values of the first random bit sequence and the selected preparation basis, a corresponding quantum light signal (ideally a single-photon quantum state, but often a weakly coherent light pulse containing a small number of photons) is prepared using a micro-quantum light source. The prepared quantum light signal is sent to a quantum signal receiver via a free-space (air) channel through a micro-optical system (lenses, mirrors, etc.) and a tracking system.

[0012] The quantum signal receiving end continuously receives the quantum light signal sent by the quantum signal sending end, and dynamically adjusts the detector position of the quantum signal receiving end so that the quantum light signal is continuously aligned with the detector;

[0013] A random number generator independently generates a string of random sequences for selecting a measurement basis (again, H / V basis or D / A basis). Based on the selected measurement basis, an integrated single-photon detector (possibly with a beam splitter) is used to measure the received quantum light signal. If the measurement basis and the preparation basis are the same, the measurement result is consistent with the bit value sent by the quantum signal transmitter at that position (taking into account factors such as optical loss, background light, and eavesdropping, there may be a small inconsistency). Each measurement result and the measurement basis used are recorded.

[0014] In one embodiment, the present invention provides a method for quantum key distribution for mobile communication terminals, wherein the step of retaining bit positions of the same basis used by a quantum signal transmitting end and a quantum signal receiving end as a first key, selecting a portion of bits of the first key, verifying an error rate of the selected bits, and verifying that the error rate is lower than a preset security threshold, and using the remaining unselected first keys as a second key, specifically includes:

[0015] The quantum signal transmitter and receiver communicate the type of basis used in each transmission / reception through a classical channel (only the choice of basis is announced, never the specific bit values sent / measured). Bit positions using different bases are discarded, and bit positions using the same base are retained to obtain the first key.

[0016] Randomly select a portion of bits (e.g., 10-20%) from the first key to obtain the selected bits, publicly compare the values of the selected bits over a classical channel, and calculate the Quantum Bit Error Rate (QBER) of the publicly compared selected bits;

[0017] If the error rate of the selected bits is lower than the preset security threshold (determined by the protocol, channel loss, detector dark count, etc.), the remaining part of the first key that has not been publicly compared is used as the second key (it is considered that no significant eavesdropping has occurred, or the degree of eavesdropping discovered is very low and can be tolerated); if the error rate of the selected bits exceeds the security threshold (indicating that there is an eavesdropper in the channel or the noise is too large), the first key is discarded.

[0018] In one embodiment, the present invention provides a method for quantum key distribution for a mobile communication terminal, wherein the steps of correcting inconsistencies in the second keys of a quantum signal transmitter and a quantum signal receiver to obtain a third key, converting the third key using a universal hash function to obtain a shorter but more secure fourth key as a key for information encryption, specifically include:

[0019] Using error-correcting codes (such as Cascade and LDPC) over a classical channel, the quantum signal sender and receiver negotiate error correction information, identifying and correcting any inconsistent bits in the second key between the two, ultimately obtaining a completely consistent third key. (This process leaks a small amount of key information, requiring subsequent security enhancement.)

[0020] The quantum signal sending end and the quantum signal receiving end negotiate to use a universal hash function to compress / convert the third key to generate a shorter but more secure fourth key as the key for information encryption.

[0021] In one embodiment, the present invention provides a method for quantum key distribution on a mobile communication terminal, the method further comprising the following steps:

[0022] The quantum signal transmitter is controlled to randomly select one of three intensities each time it sends a quantum light signal. The three intensities include a signal state that carries the key, a decoy state that does not carry the key, and a vacuum state that contains no information (the signal state has a higher intensity and is used to carry key information, with a typical average photon number of around 0.5. The decoy state has a significantly lower intensity than the signal state, with a typical average photon number of around 0.1, and does not carry valid key information; the vacuum state has zero intensity and no photons are sent). The quantum light signal is prepared and sent according to the selected intensity.

[0023] Control the quantum signal receiving end to receive the quantum light signal. After completing the preparation and selection of base comparisons, control the quantum signal sending end to publish the intensity labels of each quantum light signal, and obtain the valid data subsets successfully detected by the quantum signal receiving end: the signal state valid set (generating the second key master data), the decoy state valid set (attack detection), and the vacuum state valid set (calibrating the detector background noise);

[0024] Calculate the error rate (QBER) of the selected bits of the signal state active set and the decoy state active set respectively; if the absolute value of the difference between the error rates of the two selected bits is within the allowable range (generally required to be less than 0.5%-1%, and can be appropriately increased due to increased channel noise over long distances), the second key is safe and usable; if the absolute value of the difference between the error rates of the two selected bits is not within the allowable range, it is determined that eavesdropping has occurred and the second key is discarded.

[0025] In one embodiment, the present invention provides a quantum key distribution system for a mobile communication terminal, comprising:

[0026] A signal sending and receiving module is used to prepare a quantum light signal through a quantum signal sending end. The quantum light signal includes the bit value of the first string of random bit sequences and a selected preparation basis. The quantum light signal is received through a quantum signal receiving end, and a measurement basis is randomly selected. If the measurement basis and the preparation basis are the same, the bit value sent by the quantum signal sending end at that position is obtained.

[0027] A first key processing module is configured to retain bit positions using the same basis at the quantum signal transmitting end and the quantum signal receiving end as the first key, select a portion of the bits of the first key, verify the error rate of the selected bits, and if the error rate is lower than a preset security threshold, use the remaining unselected first keys as the second key;

[0028] The second key processing module is used to correct the inconsistency of the second keys of the quantum signal sending end and the quantum signal receiving end to obtain a third key, and convert the third key through a universal hash function to obtain a shorter but more secure fourth key as the key for information encryption.

[0029] In one embodiment, the present invention provides a quantum key distribution system for a mobile communication terminal, wherein the signal sending and receiving module includes:

[0030] A sending content selection unit is used to control the quantum signal sending end to generate a first random bit sequence and a second random bit sequence, where the second random bit sequence is used to select a preparation basis (H / V basis or D / A basis);

[0031] The quantum light signal sending unit is used to prepare the corresponding quantum light signal (ideally a single-photon quantum state, but often a weakly coherent light pulse containing a small number of photons) using a micro-quantum light source based on the bit values of the first random bit sequence and the selected preparation basis. The prepared quantum light signal is sent to the quantum signal receiving end via a free-space (air) channel through a micro-optical system (lenses, mirrors, etc.) and a tracking system.

[0032] A quantum light signal receiving unit is used to continuously receive the quantum light signal sent by the quantum signal sending end through the quantum signal receiving end, and dynamically adjust the detector position of the quantum signal receiving end so that the quantum light signal is continuously aligned with the detector;

[0033] The measurement result acquisition unit is used to independently generate a string of random sequences through a random number generator for selecting a measurement basis (similarly, H / V basis or D / A basis); based on the selected measurement basis, an integrated single-photon detector (which may require a beam splitter) is used to measure the received quantum light signal. If the measurement basis and the preparation basis are the same, the measurement result is consistent with the bit value sent by the quantum signal transmitter at that position (taking into account factors such as optical loss, background light, and eavesdropping, there may be a small inconsistency); each measurement result and the measurement basis used are recorded.

[0034] In one embodiment, the present invention provides a quantum key distribution system for a mobile communication terminal, wherein the first key processing module includes:

[0035] A first key acquisition unit is configured to mutually inform the quantum signal transmitter and the quantum signal receiver via a classical channel of the type of basis used by each in each transmission / reception (only the selection of the basis is announced, and the specific bit values sent / measured are never announced); discard bit positions that use different bases, retain bit positions that use the same base, and obtain a first key;

[0036] an error rate calculation unit, configured to randomly select a portion of bits (e.g., 10-20%) from the first key to obtain the selected bits, publicly compare the values of the selected bits via a classical channel, and calculate the error rate (Quantum Bit Error Rate, QBER) of the publicly compared selected bits;

[0037] The second key acquisition unit is used to use the remaining part of the first key that has not been publicly compared as the second key if the error rate of the selected bits is lower than a preset security threshold (determined by the protocol, channel loss, detector dark count, etc.) (it is considered that no significant eavesdropping has occurred, or the degree of eavesdropping discovered is very low and can be tolerated); if the error rate of the selected bits exceeds the security threshold (indicating that there is an eavesdropper in the channel or the noise is too loud), the first key is discarded.

[0038] In one embodiment, the present invention provides a quantum key distribution system for a mobile communication terminal, wherein the second key processing module includes:

[0039] The third key acquisition unit is used to use error-correcting codes (such as Cascade, LDPC, etc.) to negotiate error correction information between the quantum signal sender and the quantum signal receiver through a classical channel, identify and correct inconsistent bits in the second keys of the quantum signal sender and the quantum signal receiver, and ultimately obtain a completely consistent third key (this process will leak a small amount of information about the key, which requires subsequent confidentiality enhancement processing);

[0040] The fourth key acquisition unit is used to control the quantum signal sending end and the quantum signal receiving end to negotiate the use of a universal hash function to compress / convert the third key and generate a shorter but more secure fourth key as the key for information encryption (in order to eliminate information that may be leaked during the error correction process and information that may be obtained by any potential eavesdropper, and enhance the confidentiality of the third key).

[0041] In one embodiment, the present invention provides a mobile communication terminal quantum key distribution system, the mobile communication terminal quantum key distribution system further comprising:

[0042] The intensity-dividing transmission module is used to control the quantum signal transmitter to randomly select one of three intensities each time it sends a quantum light signal. The three intensities include a signal state that carries a key, a decoy state that does not carry a key, and a vacuum state that contains no information (the signal state has a higher intensity and is used to carry key information, with a typical average photon number of about 0.5. The decoy state has a significantly lower intensity than the signal state, with a typical average photon number of about 0.1, and does not carry valid key information; the vacuum state has a zero intensity and does not send photons). The quantum light signal is prepared and sent according to the selected intensity.

[0043] The valid set classification module is used to control the quantum signal receiving end to receive quantum light signals. After completing the preparation basis and measurement basis comparison, it controls the quantum signal sending end to publish the intensity labels of each quantum light signal, and obtain the valid data subsets successfully detected by the quantum signal receiving end: the signal state valid set (generating the second key master data), the decoy state valid set (attack detection), and the vacuum state valid set (calibrating the detector background noise);

[0044] The attack judgment module is used to calculate the error rate (QBER) of the selected bits of the signal state valid set and the decoy state valid set respectively; if the absolute value of the difference between the error rates of the two selected bits is within the allowable range (generally required to be less than 0.5%-1%, and can be appropriately increased due to increased channel noise over long distances), the second key is safe and usable; if the absolute value of the difference between the error rates of the two selected bits is not within the allowable range, it is determined that eavesdropping has occurred and the second key is discarded.

[0045] Compared with the prior art, the beneficial effects of the present invention are: the present invention converts the third key through a universal hash function. As long as the minimum entropy of the initial key meets the security requirements, the hash output can ensure that the attacker's probability of guessing the final key decreases exponentially, and the amount of key information possessed by the attacker is compressed to a negligible level, so that the reliability of the fourth key finally obtained is high; by setting quantum light signals of different intensities, it is possible to verify whether eavesdropping occurs and reduce the possibility of key leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A schematic diagram of the first part of the flow chart of a method for quantum key distribution for a mobile communication terminal provided in an embodiment of the present invention.

[0047] Figure 2 A schematic diagram of the process of preparing, sending, receiving, and processing quantum optical signals provided by an embodiment of the present invention.

[0048] Figure 3 A schematic diagram of the process of obtaining the first key and the second key provided in an embodiment of the present invention.

[0049] Figure 4 A schematic diagram of the process of obtaining the third key and the fourth key provided in an embodiment of the present invention.

[0050] Figure 5 A schematic flow chart of the second part of a method for quantum key distribution for a mobile communication terminal provided in an embodiment of the present invention.

[0051] Figure 6 A schematic diagram of the first part of a quantum key distribution system for mobile communication terminals provided in an embodiment of the present invention.

[0052] Figure 7 A schematic diagram of a signal sending and receiving module provided in an embodiment of the present invention.

[0053] Figure 8 A schematic diagram of a first key processing module provided in an embodiment of the present invention.

[0054] Figure 9 A schematic diagram of a second key processing module provided in an embodiment of the present invention.

[0055] Figure 10 Schematic diagram of the second part of a quantum key distribution system for mobile communication terminals provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0057] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but unless otherwise specified, these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, a first xx script may be referred to as a second xx script, and similarly, a second xx script may be referred to as a first xx script without departing from the scope of this application.

[0058] In one embodiment, Figure 1 As shown, a method for quantum key distribution of a mobile communication terminal includes the following steps:

[0059] Step S1: A quantum light signal is prepared by a quantum signal transmitter. The quantum light signal includes the bit values of a first random bit sequence and a selected preparation basis. The quantum light signal is received by a quantum signal receiver, and a measurement basis is randomly selected. If the measurement basis and the preparation basis are the same, the bit value sent by the quantum signal transmitter at that position is obtained.

[0060] Step S2: retaining the bit positions of the same basis used by the quantum signal transmitting end and the quantum signal receiving end as the first key, selecting a portion of the bits of the first key, and verifying the error rate of the selected bits. If the error rate is lower than a preset security threshold, the remaining unselected first keys are used as the second key.

[0061] Step S3: Correct the inconsistency of the second keys of the quantum signal sending end and the quantum signal receiving end to obtain a third key. Convert the third key through a universal hash function to obtain a shorter but more secure fourth key as the key for information encryption.

[0062] Steps S1-S3 constitute the core protocol flow of quantum key distribution (QKD). Their design goal is to establish an unconditionally secure shared secret key over an insecure quantum channel and a public classical channel based on quantum mechanical principles (such as the uncertainty principle and the no-cloning theorem). Step S1 (quantum transmission and initial measurement) provides the physical foundation: the quantum signal transmitter randomly selects a bit value and a preparation basis (such as H / V or D / A) to encode a quantum state (such as the polarization state of a single photon). The quantum signal receiver randomly selects a measurement basis for detection. Only when both parties choose the same basis will the measurement result at the quantum signal receiver be consistent with the bit sent by the quantum signal transmitter. This exploits the perturbation properties of quantum states in measurements of mismatched bases. Step S2 (basis comparison, screening, and error rate estimation) is crucial for security verification: both parties publicly disclose only the comparison basis selection (never revealing the bit value) over a classical channel, filtering out positions with inconsistent bases to obtain the first secret key. A portion of the bit error rate (QBER) is then randomly disclosed. If the QBER is below the security threshold, it indicates that channel noise or eavesdropping interference is controllable, and the remaining bits are retained as the second key. Otherwise, the key is discarded, as a high error rate may indicate eavesdropping. Step S3 (key agreement and confidentiality enhancement) provides information-theoretic security: error correction information is negotiated to eliminate any remaining inconsistent bits in the second keys of both parties, resulting in a consistent third key. This process leaks a small amount of key information. Finally, the third key is compressed through random extraction using a universal hash function to generate a shorter, yet information-theoretically secure, fourth key. The key to hash compression is that even if an eavesdropper possesses partial information about the third key, the random extraction reduces their information about the final key exponentially to a negligible level, thus meeting the key confidentiality security requirement.

[0063] In one embodiment, Figure 2 As shown, a method for quantum key distribution of a mobile communication terminal, in step S1, a quantum signal transmitting end prepares a quantum light signal, the quantum light signal including the bit value of a first string of random bit sequences and a selected preparation basis, a quantum signal receiving end receives the quantum light signal, and randomly selects a measurement basis. If the measurement basis and the preparation basis are the same, the step of obtaining the bit value sent by the quantum signal transmitting end at the position specifically includes:

[0064] Step S11, controlling the quantum signal transmitter to generate a first random bit sequence and a second random bit sequence, wherein the second random bit sequence is used to select a preparation basis (H / V basis or D / A basis);

[0065] Step S12: Based on the bit values of the first random bit sequence and the selected preparation basis, a corresponding quantum light signal (ideally a single-photon quantum state, but often a weakly coherent light pulse containing a small number of photons) is prepared using a micro-quantum light source. The prepared quantum light signal is transmitted to a quantum signal receiving end via a free-space (air) channel through a micro-optical system (lenses, mirrors, etc.) and a tracking system.

[0066] Step S13, continuously receiving the quantum light signal sent by the quantum signal sending end through the quantum signal receiving end, and dynamically adjusting the detector position of the quantum signal receiving end so that the quantum light signal is continuously aligned with the detector;

[0067] In step S14, a random number generator independently generates a random sequence for selecting a measurement basis (again, H / V basis or D / A basis). Based on the selected measurement basis, the received quantum light signal is measured using an integrated single-photon detector (possibly with a beam splitter). If the measurement basis and the preparation basis are the same, the measurement result is consistent with the bit value sent by the quantum signal transmitter at that location (minor inconsistencies may exist due to factors such as optical loss, background light, and eavesdropping). Each measurement result and the measurement basis used are recorded.

[0068] Step S11 ensures the unpredictability of the key by independently generating two random sequences (a bit sequence and a basis selection sequence), which is the basis for resisting eavesdropping. The key to step S12 lies in miniaturization and channel adaptation: weak coherent optical pulses (non-ideal single photons) are used to accommodate the light source limitations of mobile terminals; a micro-optical system focuses the optical path, and a tracking system dynamically compensates for free-space channel offsets caused by terminal movement to maintain signal transmission stability. Step S13 emphasizes real-time alignment, utilizing feedback control to continuously adjust the detector position to address beam drift in mobile scenarios and ensure detection efficiency. Step S14 completes random decoding at the receiver: the receiver independently and randomly selects a measurement basis, performs basis-related measurements using an integrated single-photon detector (e.g., a beam splitter + detector combination), and records the results and basis information.

[0069] In one embodiment, Figure 3 As shown, a method for quantum key distribution for a mobile communication terminal, wherein step S2, retaining bit positions of the same basis used by a quantum signal transmitting end and a quantum signal receiving end as a first key, selecting a portion of bits of the first key, verifying an error rate of the selected bits, and verifying that the error rate is lower than a preset security threshold, and using the remaining unselected first keys as the second key, specifically includes:

[0070] Step S21: The quantum signal transmitter and the quantum signal receiver inform each other via a classical channel of the type of basis used in each transmission / reception (only the selection of the basis is announced, and the specific bit values sent / measured are never announced). Bit positions using different bases are discarded, and bit positions using the same base are retained to obtain a first key.

[0071] Step S22: Randomly select a portion of bits (e.g., 10-20%) from the first key to obtain selected bits, publicly compare the values of the selected bits through a classical channel, and calculate the error rate (Quantum Bit Error Rate, QBER) of the selected bits in the public comparison;

[0072] In step S23, if the error rate of the selected bits is lower than a preset security threshold (determined by the protocol, channel loss, detector dark count, etc.), the remaining part of the first key that has not been publicly compared is used as the second key (it is considered that no significant eavesdropping has occurred, or the degree of detection of the eavesdropping behavior is very low and can be tolerated); if the error rate of the selected bits exceeds the security threshold (indicating that there is an eavesdropper in the channel or the noise is too loud), the first key is discarded.

[0073] Step S21 (Basis Comparison and Initial Key Screening) requires both parties to disclose only the basis selection sequence (without revealing bit values). Bit positions with inconsistent bases (approximately 50%) are discarded through comparison, retaining bits with matching bases to form the first key. This exploits the perturbative nature of quantum states when measuring non-matching bases: an eavesdropper's incorrect guess of the basis introduces error, and disclosing the basis type does not reveal key information. Step S22 (Random Sampling and QBER Estimation) randomly selects a subset of bits from the first key for public comparison (e.g., 10%) and calculates the quantum bit error rate (QBER). This sample error rate represents the overall channel quality. Step S23 (Security Threshold Determination) compares the QBER to a preset threshold (determined by device parameters and protocol). If the QBER is below the threshold, the eavesdropping interference is considered manageable, and the remaining bits are retained as the second key. If the QBER exceeds the threshold, eavesdropping is determined to be present or the channel is unreliable, and the key is immediately discarded.

[0074] In one embodiment, Figure 4 As shown, a method for quantum key distribution for a mobile communication terminal, wherein step S3 corrects inconsistencies between the second keys of the quantum signal transmitting end and the quantum signal receiving end to obtain a third key, converts the third key using a universal hash function to obtain a shorter but more secure fourth key as a key for information encryption, specifically includes:

[0075] Step S31: Using an error-correcting code (such as Cascade or LDPC) over a classical channel, the quantum signal transmitter and receiver negotiate error correction information to identify and correct any inconsistent bits in the second key between the quantum signal transmitter and receiver, ultimately obtaining a completely consistent third key. (This process leaks a small amount of key information, requiring subsequent security enhancement.)

[0076] Step S32: Control the quantum signal sending end and the quantum signal receiving end to negotiate and use a universal hash function to compress / convert the third key to generate a shorter but more secure fourth key as the key for information encryption.

[0077] Due to the presence of noise in actual systems, such as detector dark counts, optical loss, background light, and possible residual undetected eavesdropping, there may be small inconsistencies (bit errors) between the second keys at the quantum signal transmitter and receiver. Therefore, error correction is required.

[0078] In step S32, both parties compress and enhance the security of the third key using a randomly selected universal hash function to generate the final key (the fourth key). The specific process is as follows: First, the quantum signal transmitter and receiver negotiate a randomly selected hash function (e.g., dynamically generated based on a preset function library) via a classical channel. The corrected third key (longer in length) is then fed into this function and compressed into a shorter bit string (e.g., 100,000 bits compressed to 80,000 bits) through a mathematical mapping. This compression not only reduces length but also serves as a core security guarantee. Due to the randomness and unique mathematical properties of the hash function, even if an eavesdropper obtains a small amount of key information during early stages (e.g., error correction), the compression process dilutes that information to near-ineffectiveness. The final output fourth key is statistically indistinguishable from a completely random key, making it impossible for an eavesdropper to extract valid information, thus ensuring sufficient security from an information-theoretic perspective.

[0079] In one embodiment, Figure 5 As shown, a method for distributing quantum keys to a mobile communication terminal further includes the following steps:

[0080] Step S4: Controlling the quantum signal transmitter to randomly select one of three intensities each time a quantum light signal is transmitted. The three intensities include a signal state that carries a key, a decoy state that does not carry a key, and a vacuum state that contains no information (the signal state has a higher intensity and is used to carry key information, with a typical average photon number of about 0.5. The decoy state has a significantly lower intensity than the signal state, with a typical average photon number of about 0.1, and does not carry valid key information. The vacuum state has a zero intensity and does not transmit photons). Prepare and transmit a quantum light signal according to the selected intensity;

[0081] Step S5: Control the quantum signal receiving end to receive the quantum light signal. After completing the preparation and selection of base comparisons, control the quantum signal transmitting end to publish the strength labels of each quantum light signal, and obtain the valid data subsets successfully detected by the quantum signal receiving end: the signal state valid set (generating the second key master data), the decoy state valid set (attack detection), and the vacuum state valid set (calibrating the detector background noise);

[0082] Step S6, respectively calculate the error rate (QBER) of the selected bits of the signal state active set and the decoy state active set; if the absolute value of the difference between the error rates of the two selected bits is within the allowable range (generally required to be less than 0.5%-1%, and can be appropriately increased due to increased channel noise over long distances), the second key is safe and usable; if the absolute value of the difference between the error rates of the two selected bits is not within the allowable range, it is determined that eavesdropping has occurred and the second key is discarded.

[0083] Considering that attacks using protocol implementation or device physical defects may result in the error rate not exceeding the security threshold, the attack is not detected, and the attacker obtains part or even all information about the second key. Actual example:

[0084] 1. Attacking the quantum signal receiver: This attack targets single-photon detector vulnerabilities, such as blinding attacks, strong light triggering attacks, and time shift attacks. The attacker sends strong light to saturate the detector or generate false counts on demand, thereby controlling the measurement results of the quantum signal receiver.

[0085] 2. Attacking the quantum signal transmitter: Targeting non-ideal light sources (such as vulnerabilities in the intensity modulator in the decoy state protocol). The attacker may force the light source to emit unexpected light pulses;

[0086] 3. Wavelength attack / channel attack: exploiting the wavelength dependence of optical components (such as beam splitters and filters) to launch attacks.

[0087] Steps S4 to S6 are the core implementation of the decoy state protocol, designed to address security vulnerabilities in real-world systems that use weakly coherent light sources rather than ideal single-photon sources. In step S4, the transmitter randomly switches between three optical pulse intensities (signal state, decoy state, and vacuum state): the signal state (high intensity) carries valid key bits; the decoy state (extremely low intensity) carries no key information; and the vacuum state (zero photons) is used for noise calibration. This randomization prevents eavesdroppers from distinguishing pulse types. Any attempt to intercept or re-emit photons (e.g., in a photon number splitting attack) would interfere equally with all pulses. In step S5, after basis comparison, the intensity labels are published. The receiver then uses these labels to classify the detected data into three groups: a valid signal state set (for key generation), a valid decoy state set (for security monitoring), and a valid vacuum state set (for noise floor calibration). Step S6 compares the error rate (QBER) of the signal and decoy states to determine security. If the difference between the two is minimal (e.g., <1%), eavesdropping is not occurring (an attack would significantly increase the difference); if the difference exceeds a threshold, a targeted attack is underway, and the key is immediately discarded.

[0088] In one embodiment, Figure 6 As shown, a quantum key distribution system for mobile communication terminals includes:

[0089] Signal sending and receiving module 1 is used to prepare a quantum light signal through a quantum signal sending end. The quantum light signal includes the bit value of the first string of random bit sequences and the selected preparation basis. The quantum light signal is received through a quantum signal receiving end, and a measurement basis is randomly selected. If the measurement basis and the preparation basis are the same, the bit value sent by the quantum signal sending end at that position is obtained.

[0090] The first key processing module 2 is used to retain the bit positions of the same basis used by the quantum signal transmitting end and the quantum signal receiving end as the first key, select a portion of the bits of the first key, verify the error rate of the selected bits, and if the error rate is lower than a preset security threshold, the remaining first keys that were not selected are used as the second key;

[0091] The second key processing module 3 is used to correct the inconsistency of the second keys of the quantum signal sending end and the quantum signal receiving end to obtain a third key, and convert the third key through a universal hash function to obtain a shorter but more secure fourth key as the key for information encryption.

[0092] In the first key processing module 2, the preset security threshold can easily lead to key interruption due to the dynamic changes in channel noise in mobile scenarios. Real-time noise monitoring and parameter adaptation can be introduced to dynamically adjust the security threshold based on instantaneous channel loss (such as weather and occlusion) and detector dark counts.

[0093] In one embodiment, Figure 7 As shown, a quantum key distribution system for a mobile communication terminal, the signal sending and receiving module 1 includes:

[0094] The sending content selection unit 11 is used to control the quantum signal sending end to generate a first random bit sequence and a second random bit sequence, where the second random bit sequence is used to select a preparation basis (H / V basis or D / A basis);

[0095] The quantum light signal transmitting unit 12 is configured to generate a corresponding quantum light signal (ideally a single-photon quantum state, but in practice often a weakly coherent light pulse containing a small number of photons) using a micro-quantum light source based on the bit values of the first random bit sequence and the selected preparation basis; and transmit the generated quantum light signal to a quantum signal receiving end via a free-space (air) channel through a micro-optical system (lenses, reflectors, etc.) and a tracking system.

[0096] The quantum light signal receiving unit 13 is used to continuously receive the quantum light signal sent by the quantum signal sending end through the quantum signal receiving end, and dynamically adjust the detector position of the quantum signal receiving end so that the quantum light signal is continuously aligned with the detector;

[0097] The measurement result acquisition unit 14 is used to independently generate a random sequence using a random number generator for selecting a measurement basis (again, H / V basis or D / A basis). Based on the selected measurement basis, the integrated single-photon detector (possibly requiring a beam splitter) is used to measure the received quantum light signal. If the measurement basis and the preparation basis are the same, the measurement result is consistent with the bit value sent by the quantum signal transmitter at that location (taking into account factors such as optical loss, background light, and eavesdropping, there may be slight inconsistencies). Each measurement result and the measurement basis used are recorded.

[0098] In the quantum optical signal receiving unit 13, free-space dynamic alignment relies on traditional feedback control, which has limited response speed. AI-based predictive beam tracking can be introduced. Using a deep learning model, this model analyzes the quantum signal receiving end's motion trajectory (e.g., gyroscope data) and environmental disturbances (e.g., turbulence) in real time to predict the direction of beam deviation. This in turn drives the microelectromechanical system (MEMS) lens to pre-compensate the optical path, reducing tracking latency from milliseconds to microseconds. This significantly improves the efficiency of quantum signal reception in mobile environments (e.g., vehicles and drones) and reduces bit error rates.

[0099] In one embodiment, Figure 8 As shown, a quantum key distribution system for a mobile communication terminal, the first key processing module 2 includes:

[0100] A first key acquisition unit 21 is configured to mutually inform the quantum signal transmitter and the quantum signal receiver via a classical channel of the type of basis used by each of them in each transmission / reception (only the selection of the basis is announced, and the specific bit values sent / measured are never announced); discard bit positions that use different bases, retain bit positions that use the same base, and obtain a first key;

[0101] An error rate calculation unit 22 is configured to randomly select a portion of bits (e.g., 10-20%) from the first key to obtain the selected bits, publicly compare the values of the selected bits via a classical channel, and calculate the error rate (Quantum Bit Error Rate, QBER) of the publicly compared selected bits;

[0102] The second key acquisition unit 23 is used to use the remaining part of the first key that has not been publicly compared as the second key if the error rate of the selected bits is lower than a preset security threshold (determined by the protocol, channel loss, detector dark count, etc.) (it is considered that no significant eavesdropping has occurred, or the degree of detection of the eavesdropping behavior is very low and can be tolerated); if the error rate of the selected bits exceeds the security threshold (indicating that there is an eavesdropper in the channel or the noise is too loud), the first key is discarded.

[0103] The first key acquisition unit 21 selects the key completely randomly (50% probability for each), which can easily be exploited by eavesdroppers. Active defense key selection strategies can be introduced, such as dynamic probability adjustment, to dynamically adjust the ratio of H / V and D / A keys based on the real-time channel noise level (for example, increasing the proportion of keys with stronger anti-interference properties when noise is high).

[0104] In one embodiment, Figure 9 As shown, a quantum key distribution system for a mobile communication terminal, the second key processing module 3 includes:

[0105] A third key acquisition unit 31 is configured to use an error-correcting code (such as Cascade, LDPC, etc.) to negotiate error correction information between the quantum signal transmitter and the quantum signal receiver via a classical channel, identify and correct any inconsistent bits in the second keys between the quantum signal transmitter and the quantum signal receiver, and ultimately obtain a completely consistent third key (this process will leak a small amount of key information, requiring subsequent confidentiality enhancement processing);

[0106] The fourth key acquisition unit 32 is used to control the quantum signal sending end and the quantum signal receiving end to negotiate the use of a universal hash function to compress / convert the third key and generate a shorter but more secure fourth key as the key for information encryption (in order to eliminate information that may be leaked during the error correction process and information that may be obtained by any potential eavesdropper, and enhance the confidentiality of the third key).

[0107] The third key acquisition unit 31 uses fixed error correction protocols (such as Cascade and LDPC), which are inefficient when mobile channels fluctuate. This can be expanded to AI-driven dynamic scheduling of error correction resources: a trained neural network analyzes channel error patterns (such as burst errors or uniform errors) in real time and automatically selects the optimal error correction algorithm (LDPC for low error rates and Cascade for high error rates).

[0108] In one embodiment, Figure 10 As shown, a mobile communication terminal quantum key distribution system, the mobile communication terminal quantum key distribution system also includes:

[0109] The intensity division and transmission module 4 is used to control the quantum signal transmitter to randomly select one of three intensities each time it transmits a quantum light signal. The three intensities include a signal state that carries a key, a decoy state that does not carry a key, and a vacuum state that contains no information (the signal state has a higher intensity and is used to carry key information, with a typical average photon number of about 0.5. The decoy state has a significantly lower intensity than the signal state, with a typical average photon number of about 0.1, and does not carry valid key information; the vacuum state has a zero intensity and does not transmit photons). The quantum light signal is prepared and transmitted according to the selected intensity.

[0110] The valid set classification module 5 is used to control the quantum signal receiving end to receive quantum light signals. After completing the preparation basis and measurement basis comparison, it controls the quantum signal sending end to publish the intensity labels of each quantum light signal, and obtain the valid data subsets successfully detected by the quantum signal receiving end: the signal state valid set (generating the second key master data), the decoy state valid set (attack detection), and the vacuum state valid set (calibrating the detector background noise);

[0111] Attack judgment module 6 is used to calculate the error rate (QBER) of the selected bits of the signal state active set and the decoy state active set respectively; if the absolute value of the difference between the error rates of the two selected bits is within the allowable range (generally required to be less than 0.5%-1%, and can be increased appropriately due to increased channel noise over long distances), the second key is safe and usable; if the absolute value of the difference between the error rates of the two selected bits is not within the allowable range, it is determined that eavesdropping has occurred and the second key is discarded.

[0112] The fixed-intensity decoy state in intensity-split transmission module 4 has poor adaptability in mobile channels. This can be expanded to adaptive intensity control: This involves real-time monitoring of channel losses (such as atmospheric turbulence and rain and fog) to dynamically adjust the mean photon counts of the signal and decoy states (for example, increasing the signal state intensity to 0.8 photons / pulse when losses are high). A reinforcement learning model is used to optimize the emission ratio of the three intensities (for example, increasing the decoy state ratio to 40% in high-noise situations) to maximize the secure key rate. Furthermore, closed-loop feedback based on detector efficiency data at the quantum signal receiving end can be used to prevent detector saturation caused by excessively strong pulses.

[0113] It should be understood that, although the various steps in the flow chart of each embodiment of the present invention are shown in sequence according to the indication of the arrows, these steps are not necessarily performed in sequence according to the order indicated by the arrows. Unless otherwise specified herein, the execution of these steps is not strictly limited in order, and these steps can be performed in other orders. Moreover, at least a portion of the steps in each embodiment may include a plurality of sub-steps or a plurality of stages, and these sub-steps or stages are not necessarily performed at the same time, but can be performed at different times, and the execution order of these sub-steps or stages is not necessarily performed in sequence, but can be performed in turn or alternately with at least a portion of other steps or sub-steps or stages of other steps.

[0114] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0115] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

[0116] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0117] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for quantum key distribution in a mobile communication terminal, characterized in that: The mobile communication terminal quantum key distribution method comprises the following steps: A quantum light signal is prepared by a quantum signal transmitter. The quantum light signal includes the bit value of the first random bit sequence and a selected preparation basis. The quantum light signal is received by a quantum signal receiver, and a measurement basis is randomly selected. If the measurement basis and the preparation basis are the same, the bit value sent by the quantum signal transmitter at that position is obtained. The bit positions of the quantum signal transmitter and the quantum signal receiver using the same basis are retained as the first key. A portion of the bits of the first key are selected, and the error rate of the selected bits is verified. If the error rate is lower than a preset security threshold, the remaining first keys that were not selected are used as the second key. The inconsistency of the second keys of the quantum signal sending end and the quantum signal receiving end is corrected to obtain a third key, and the third key is converted through a universal hash function to obtain a shorter but more secure fourth key, which is used as the key for information encryption.

2. The method for quantum key distribution of mobile communication terminals according to claim 1, characterized in that: The step of preparing a quantum light signal by a quantum signal transmitting end, the quantum light signal including the bit value of the first string of random bit sequences and the selected preparation basis, receiving the quantum light signal by a quantum signal receiving end, and randomly selecting a measurement basis, and obtaining the bit value sent by the quantum signal transmitting end at the position if the measurement basis and the preparation basis are the same, specifically includes: Controlling the quantum signal transmitter to generate a first random bit sequence and a second random bit sequence, wherein the second random bit sequence is used to select a preparation basis; Based on the bit values of the first random bit sequence and the selected preparation basis, a corresponding quantum light signal is prepared by a micro-quantum light source; the prepared quantum light signal is sent to a quantum signal receiving end via a free-space channel through a micro-optical system and a tracking system; The quantum signal receiving end continuously receives the quantum light signal sent by the quantum signal sending end, and dynamically adjusts the detector position of the quantum signal receiving end so that the quantum light signal is continuously aligned with the detector; A random number generator independently generates a random sequence for selecting a measurement basis. Based on the selected measurement basis, the received quantum light signal is measured using an integrated single-photon detector. If the measurement basis and the preparation basis are the same, the measurement result is consistent with the bit value sent by the quantum signal transmitter at that position. Each measurement result and the measurement basis used are recorded.

3. The method for quantum key distribution of mobile communication terminals according to claim 1, characterized in that: The step of retaining bit positions of the same basis used by the quantum signal transmitting end and the quantum signal receiving end as the first key, selecting a portion of bits of the first key, verifying an error rate of the selected bits, and verifying that the error rate is lower than a preset security threshold, and using the remaining unselected first keys as the second key specifically includes: The quantum signal transmitter and the quantum signal receiver inform each other of the type of basis used in each transmission / reception through a classical channel; the bit positions using different bases are discarded, and the bit positions using the same base are retained to obtain a first key; Randomly selecting a portion of bits from the first key to obtain selected bits, publicly comparing values of the selected bits through a classical channel, and calculating an error rate of the publicly compared selected bits; If the error rate of the selected bits is lower than the preset security threshold, the remaining part of the first key that has not been publicly compared is used as the second key; if the error rate of the selected bits exceeds the security threshold, the first key is discarded.

4. The method for quantum key distribution of mobile communication terminals according to claim 1, characterized in that: The step of correcting the inconsistency of the second keys at the quantum signal transmitting end and the quantum signal receiving end to obtain a third key, converting the third key through a universal hash function to obtain a shorter but more secure fourth key as the key for information encryption specifically includes: Using error-correcting codes, the quantum signal transmitter and receiver negotiate error correction information over a classical channel, identifying and correcting inconsistent bits in the second key between the two, ultimately obtaining a completely consistent third key. The quantum signal sending end and the quantum signal receiving end negotiate to use a universal hash function to compress / convert the third key to generate a shorter but more secure fourth key as the key for information encryption.

5. The method for quantum key distribution of a mobile communication terminal according to any one of claims 1 to 4, characterized in that: The mobile communication terminal quantum key distribution method further comprises the following steps: The quantum signal transmitter is controlled to randomly select one of three intensities each time it sends a quantum light signal. The three intensities include a signal state that carries a key, a decoy state that does not carry a key, and a vacuum state that contains no information. The quantum light signal is prepared and sent according to the selected intensity. Control the quantum signal receiving end to receive the quantum light signal. After completing the preparation basis and selection basis comparison, control the quantum signal sending end to publish the intensity labels of each quantum light signal, and obtain the valid data subsets successfully detected by the quantum signal receiving end: the signal state valid set, the decoy state valid set, and the vacuum state valid set. Calculate the error rates of the selected bits of the signal state valid set and the decoy state valid set respectively; if the absolute value of the difference between the error rates of the selected bits of the two is within the allowed range, the second key is safe and available; if the absolute value of the difference between the error rates of the selected bits of the two is not within the allowed range, it is determined that eavesdropping has occurred and the second key is discarded.

6. A quantum key distribution system for mobile communication terminals, characterized in that: include: A signal sending and receiving module is used to prepare a quantum light signal through a quantum signal sending end. The quantum light signal includes the bit value of the first string of random bit sequences and a selected preparation basis. The quantum light signal is received through a quantum signal receiving end, and a measurement basis is randomly selected. If the measurement basis and the preparation basis are the same, the bit value sent by the quantum signal sending end at that position is obtained. A first key processing module is configured to retain bit positions using the same basis at the quantum signal transmitting end and the quantum signal receiving end as the first key, select a portion of the bits of the first key, verify the error rate of the selected bits, and if the error rate is lower than a preset security threshold, use the remaining unselected first keys as the second key; The second key processing module is used to correct the inconsistency of the second keys of the quantum signal sending end and the quantum signal receiving end to obtain a third key, and convert the third key through a universal hash function to obtain a shorter but more secure fourth key as the key for information encryption.

7. The mobile communication terminal quantum key distribution system according to claim 6, characterized in that: The signal sending and receiving module includes: a sending content selection unit, configured to control the quantum signal sending end to generate a first random bit sequence and a second random bit sequence, wherein the second random bit sequence is used to select a preparation basis; A quantum light signal sending unit is configured to prepare a corresponding quantum light signal using a micro quantum light source according to the bit values of the first random bit sequence and a selected preparation basis; and transmit the prepared quantum light signal to a quantum signal receiving end via a free-space channel through a micro optical system and a tracking system. A quantum light signal receiving unit is used to continuously receive the quantum light signal sent by the quantum signal sending end through the quantum signal receiving end, and dynamically adjust the detector position of the quantum signal receiving end so that the quantum light signal is continuously aligned with the detector; The measurement result acquisition unit is used to independently generate a string of random sequences through a random number generator for selecting a measurement basis; based on the selected measurement basis, the integrated single-photon detector is used to measure the received quantum light signal. If the measurement basis and the preparation basis are the same, the measurement result is consistent with the bit value sent by the quantum signal transmitter at that position; each measurement result and the measurement basis used are recorded.

8. The mobile communication terminal quantum key distribution system according to claim 6, characterized in that: The first key processing module includes: A first key acquisition unit is configured to mutually inform the quantum signal transmitter and the quantum signal receiver of the type of basis used in each transmission / reception through a classical channel; discard bit positions using different bases and retain bit positions using the same base to obtain a first key; an error rate calculation unit, configured to randomly select a portion of bits from the first key to obtain selected bits, publicly compare values of the selected bits through a classical channel, and calculate an error rate of the publicly compared selected bits; The second key acquisition unit is configured to use the remaining uncompared first key as the second key if the error rate of the selected bits is lower than a preset security threshold; and discard the first key if the error rate of the selected bits exceeds the security threshold.

9. The mobile communication terminal quantum key distribution system according to claim 6, characterized in that: The second key processing module includes: A third key acquisition unit is configured to use an error correction code to negotiate error correction information between the quantum signal transmitter and the quantum signal receiver via a classical channel, find and correct inconsistent bits in the second keys of the quantum signal transmitter and the quantum signal receiver, and ultimately obtain a completely consistent third key; The fourth key acquisition unit is used to control the quantum signal sending end and the quantum signal receiving end to negotiate and use a universal hash function to compress / convert the third key to generate a shorter but more secure fourth key as the key for information encryption.

10. The mobile communication terminal quantum key distribution system according to any one of claims 6 to 9, characterized in that: The mobile communication terminal quantum key distribution system further includes: The intensity division transmission module is used to control the quantum signal transmitter to randomly select one of three intensities each time it sends a quantum light signal. The three intensities include a signal state that carries a key, a decoy state that does not carry a key, and a vacuum state that contains no information. The quantum light signal is prepared and sent according to the selected intensity. The valid set classification module is used to control the quantum signal receiving end to receive quantum light signals. After completing the preparation basis and measurement basis comparison, it controls the quantum signal sending end to publish the intensity labels of each quantum light signal, and obtain the valid data subsets successfully detected by the quantum signal receiving end: signal state valid set, decoy state valid set, and vacuum state valid set. The attack judgment module is used to calculate the error rate of the selected bits of the signal state valid set and the decoy state valid set respectively; if the absolute value of the difference between the error rates of the selected bits of the two is within the allowed range, the second key is safe and available; if the absolute value of the difference between the error rates of the selected bits of the two is not within the allowed range, it is determined that eavesdropping has occurred and the second key is discarded.

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