Multi-layer encryption system for electronic bidding documents

Abstract

The present invention discloses a multi-layer encryption system for electronic bid documents, which specifically relates to the technical field of bid document encryption and is used to solve the problems of difficulty in detecting early decryption of encrypted bid documents and difficulty in efficiently tracing leakage paths. The system comprises a key splitting module, a false quotation generation and binding module, an early decryption verification module, a leakage tracing module, and a sequential decryption module. The system encrypts a real electronic bid document to generate an encrypted bid document, adopts a threshold encryption scheme to split a master key, combines a hash function with random perturbation, generates a surface bid document based on the real electronic bid document, calculates false quotations of the surface bid document based on different sub-key combinations used for early decryption, generates a sub-key combination-false quotation mapping, combines abnormal quotation detection and quotation mode robustness to evaluate whether the false quotation of the surface bid document has been decrypted in advance, determines the suspicious key combination used in early decryption, and decrypts the encrypted bid document within the time window allowed for bid opening.

Description

Technical Field

[0001] The present invention relates to the technical field of bid document encryption, and more particularly to a multi-layer encryption system for electronic bid documents. Background Art

[0002] Existing electronic bidding platforms generally require bidders to encrypt and transmit electronic bids and save the encrypted electronic bids. The greatest risk of electronic bid leakage lies in the leakage of private keys kept within the bidding team. Using multi-party key splitting to decompose the private key into multiple parts can effectively increase the difficulty of the key being completely stolen. However, the decryption scheme based on threshold setting does not necessarily require the thief to obtain all the split keys. Only the partial key that meets the threshold setting is required to decrypt the electronic bid. Before the bid opening, the electronic bid may be decrypted in advance due to the leakage of the bidder's private key. Pre-decryption generally leaves traces, but the traces of pre-decryption are not completely indelible. As a result, after the bid opening, the bidder suffers targeted attacks from other competitors, but it is difficult to determine whether other bidders are engaging in malicious competition based on the knowledge of their own bids.

[0003] In traditional electronic bid document encryption methods, once the bid document is encrypted, the system mainly relies on methods such as threshold encryption, digital signatures, and time locks to ensure the security of the bid document. However, traditional methods have difficulty detecting premature decryption behavior and cannot effectively trace the leaked keys. It is even more difficult to trace which specific keys have been leaked among the multiple sub-keys that have been decomposed.

[0004] In order to solve the above defects, a technical solution is now proposed. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a multi-layer encryption system for electronic bid documents. Through quotation anomaly analysis, it is detected whether the bidder's quotation deviates from the historical bidding distribution. Through bidding strategy change detection, it is analyzed whether the bidder has undergone a sudden change in the bidding strategy. It can not only discover the bidder's abnormal bidding behavior, but also determine the possibility of early decryption, breaking through the limitation of traditional encryption methods that cannot detect leakage. Through correlation analysis, it calculates the correlation between the bidder's quotation and each false quotation. By matching the leaked false quotation, it reversely infers the leaked key combination, not only discovering the early decryption behavior, but also identifying whether the bidder has malicious collusion, thereby improving the fairness of the bid.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: including a key splitting module, a false quotation generation and binding module, an advance decryption verification module, a leakage tracing module, and a sequential decryption module;

[0007] The key splitting module is used to encrypt the real electronic bid document to generate an encrypted bid document, split the master key using a threshold encryption scheme, and transmit the resulting subkeys to several members of the bidding team for storage;

[0008] The fake bid generation and binding module is used to combine hash functions and random perturbations to generate a surface bid based on the real electronic bid. It calculates the fake bid of the surface bid based on the different subkey combinations used for pre-decryption and generates a subkey combination-false bid mapping.

[0009] The pre-decryption verification module is used to detect abnormal bids based on the collected historical bid data of bidders. The module calculates the robustness of the bidders' bid patterns through time series analysis. Combining abnormal bid detection and bid pattern robustness, the module assesses whether the false bids in the surface bid documents have been decrypted in advance. If the encrypted bid document is determined to have been decrypted in advance, the module conducts leak tracing. If the encrypted bid document is determined not to have been decrypted in advance, the module performs bid opening decryption.

[0010] The leak tracing module is used to identify suspicious key combinations used in advance decryption based on the matching assessment results, issue an alarm, and verify the member that stores any subkey in the suspicious key combination;

[0011] The sequential decryption module is used to input any subkey as the activation key within the time window allowed for bid opening, generate the input order of subsequent subkeys according to the input time of the activation key, and decrypt the encrypted bid according to the subkey input order.

[0012] In a preferred embodiment, the method for splitting the master key using the threshold encryption scheme is:

[0013] After encrypting the real electronic bid, an encrypted bid is generated. The master key of the encrypted bid is K. The master key K is split using a threshold encryption scheme. The threshold encryption scheme is (k,n), where n is the total number of subkeys into which the master key K is split, and k is the minimum number of subkeys required to reconstruct the master key K. Any k subkeys can restore the master key K.

[0014] In a preferred embodiment, the method for generating a surface tender document based on a real electronic tender document is as follows:

[0015] Define the real electronic bid as Pt, which contains the real quotation Qt. Then the method for generating the surface bid is Pf = Mask(Pt, Qf), where the surface bid is Pf, the false quotation is Qf, and Mask() is the masking transformation. The expression formula of the masking transformation is Where H() is the hash function, It is a bitwise XOR operation, || is used to concatenate multiple inputs into one hash input, and Salt is a random salt value.

[0016] In a preferred embodiment, the logic for obtaining the false quotation of the surface tender is as follows:

[0017] Calculate the hash value for each subkey combination Ki that meets the threshold requirement. The calculation expression is Hi = H(Ki), where Hi is the hash value of the subkey combination Ki and H(Ki) is the unique identifier for the hash calculation of the subkey combination Ki.

[0018] For each subkey combination Ki that meets the threshold requirement, the basic perturbation value Bpv is calculated using the hash value Hi. The calculation expression is Bpv = rand(Hi) mod R, where rand(Hi) is a random number generated based on Hi, R is the perturbation range, and mod is the modulus value. Mod R is used to constrain the perturbation result to the range [0, R-1].

[0019] The calculation expression for false quotation is Qf=Qt+Bpv.

[0020] In a preferred embodiment, the method for detecting abnormal bids based on the collected historical bid data of bidders is:

[0021] Set a bidding round time window, collect the historical bid data of the bidders within the bidding round time window, and calculate the mean and standard deviation of the historical bid data to generate a normal bid distribution. The normal bid distribution is N(μ,σ), where μ is the mean of the historical bid data. The calculation expression is: Where, X e is the bid price in the e-th round, N is the number of historical bidding rounds, σ is the standard deviation of historical bidding data, and the calculation expression is:

[0022] Set the abnormal threshold to Exth and calculate the Z score of the bidder's bid data in this round as Where X is the bidder's bid data for this round. If the Z score is greater than or equal to the abnormal threshold Exth, the bidder's bid for this round is recorded as abnormal, and the electronic bid is marked as a 1A signal. If the Z score is less than the abnormal threshold Exth, the bidder's bid for this round is recorded as normal, and the electronic bid is marked as a 1B signal.

[0023] In a preferred embodiment, the method for calculating the robustness of the bidding party's bidding pattern through time series analysis is:

[0024] According to the historical bidding data of the bidders, a time series is constructed as Sc={B t-v}, B t-v is the bid data of the previous v rounds, then the robustness of the bidder’s bid pattern is calculated as B tThis is the quotation data of this round;

[0025] Set the strategy change threshold to Pcth. If |Gc| is greater than or equal to the strategy change threshold Pcth, the bidder's strategy for this round is recorded as abnormal, and the electronic bid document is marked as a 0A signal. If |Gc| is less than the strategy change threshold Pcth, the bidder's strategy for this round is recorded as normal, and the electronic bid document is marked as a 0B signal.

[0026] In a preferred embodiment, the logic for evaluating whether the false bids in the surface bid documents have been decrypted in advance by combining abnormal bid detection and bid pattern robustness is as follows:

[0027] If the electronic bid document is marked with 1A signal and 0A signal, the electronic bid document signal is updated to 00 signal. The bidder's bid is abnormal and the bidding strategy has suddenly changed. The bidder's bid and each false bid are analyzed for correlation to determine the leaked false bid.

[0028] If the electronic bid document is marked as 1A signal and 0B signal, the electronic bid document signal is updated to 10 signal. The bidder's bid is abnormal and the bidding strategy is stable. No correlation analysis is performed between the bidder's bid and each false bid.

[0029] If the electronic bid document is marked with a 1B signal and a 0A signal, the electronic bid document signal is updated to a 01 signal. The bidder's bid is normal and the bidding strategy has changed suddenly. No correlation analysis is performed between the bidder's bid and each false bid.

[0030] If the electronic bid document is marked as 1B signal and 0B signal, the electronic bid document signal is updated to 11 signal. The bidder's quotation is normal and the quotation strategy is stable. No correlation analysis is performed between the bidder's quotation and each false quotation.

[0031] In a preferred embodiment, a method for performing correlation analysis between bidder quotations and various false quotations to determine leaked false quotations is as follows:

[0032] The correlation between the bidder's bid and each false bid is calculated using the Pearson correlation coefficient. The calculation expression is: Where r is the correlation between the bidder's bid and each false bid, is the covariance between the bidder's bid and each false bid, and the calculation expression is M is the total number of historical bidding quotation data, is the bid price of the jth bidder, is the false bid generated by the subkey combination Ki in the j-th bidding, σB comp is the standard deviation of the bidder's quotation, and the calculation expression is in, is the average of historical bidders’ quotations, and the calculation expression is: is the standard deviation of false quotes, and the calculation expression is is the mean of false quotes, and the calculation expression is

[0033] The correlation threshold is set to Rth. When the calculated Pearson correlation coefficient r is greater than or equal to the correlation threshold Rth, the false quotation is marked as a relevant quotation, and it is recorded that the false quotation has a leakage risk. When the calculated Pearson correlation coefficient r is less than the correlation threshold Rth, the false quotation is marked as an irrelevant quotation, and it is recorded that the false quotation has no leakage risk.

[0034] In a preferred embodiment, if there is a false bid with a risk of leakage, the subkey combination corresponding to the false bid is determined through a subkey combination-false bid mapping, the subkey combination is marked as a suspicious key combination, and the administrator of the electronic bid multi-layer encryption system is warned to verify the holder of the subkey in the suspicious key combination;

[0035] If there is no false quotation with a risk of leakage, then within the time window allowed for the bid opening, any sub-key is input as the activation key, and the input order of subsequent sub-keys is generated according to the input time of the activation key, and the encrypted bid is decrypted according to the sub-key input order.

[0036] In a preferred embodiment, after the activation key is input, the input timestamp is recorded to ensure that the decryption order is generated based on the dynamic timestamp. A hash function is used to calculate the input order of subsequent subkeys. The calculation expression is Seed = H(T0, Kinit) mod n, where Kinit is the activation key, T0 is the activation key input timestamp, H() is the hash function, n is the total number of subkeys, mod is the modulus value, and mod n ensures that the generated index is within the key range. Seed is the seed value used to generate the key input order. The input order of subsequent subkeys is then P = Permute({1, 2, ..., n}, Seed), where Permute() is a random permutation function. The remaining k-1 subkeys are input in sequence according to the input order P of the subsequent subkeys to decrypt the encrypted bid.

[0037] If the subkeys are entered in the correct order and the subkey combination meets the threshold scheme requirements, the authentic electronic bid document will be decrypted;

[0038] If the subkeys are entered in the wrong order, the decrypted document will be the surface document, and the real electronic document cannot be obtained.

[0039] In the above technical solution, the technical effects and advantages provided by the present invention are:

[0040] By generating a surface bid, those who decrypt the bid in advance cannot obtain the real quotation and can only obtain a false quotation, thus preventing the quotation of the electronic bid from being exploited by competitors. If someone steals the electronic bid during storage or transmission, they can only see the surface bid, which will not affect the final decryption process of the real bid. The surface bid is generated based on the real bid, which effectively improves the anti-leakage ability of the electronic bid. Even if the encrypted part is cracked, there is still additional camouflage protection, which effectively prevents competitors from adjusting their quotations in advance through illegal means.

[0041] By generating a sub-key combination-false quotation mapping, the quotations decrypted in advance by different sub-key combinations are different. Even if a thief obtains part of the key, he cannot accurately infer the real quotation. Each false quotation is uniquely bound to the key combination. The changes in the bidder's quotation can be used to assess whether a sub-key leak has occurred and track the specific source of the leak. The false quotation is not fixed, but is generated based on hash functions and random perturbations, effectively blocking the way to reversely infer the real quotation. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0043] Figure 1 It is a system module diagram of the present invention. DETAILED DESCRIPTION

[0044] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0045] Example 1: Please refer to Figure 1 As shown, the present invention is a multi-layer encryption system for electronic bid documents, including a key segmentation module, a false quotation generation and binding module, an advance decryption verification module, a leakage tracing module, and a sequential decryption module;

[0046] The key splitting module is used to encrypt the real electronic bid document to generate an encrypted bid document, split the master key using a threshold encryption scheme, and transmit the resulting subkeys to several members of the bidding team for storage;

[0047] The fake bid generation and binding module is used to combine hash functions and random perturbations to generate a surface bid based on the real electronic bid. It calculates the fake bid of the surface bid based on the different subkey combinations used for pre-decryption and generates a subkey combination-false bid mapping.

[0048] The pre-decryption verification module is used to detect abnormal bids based on the collected historical bid data of bidders. The module calculates the robustness of the bidders' bid patterns through time series analysis. Combining abnormal bid detection and bid pattern robustness, the module assesses whether the false bids in the surface bid documents have been decrypted in advance. If the encrypted bid document is determined to have been decrypted in advance, the module conducts leak tracing. If the encrypted bid document is determined not to have been decrypted in advance, the module performs bid opening decryption.

[0049] The leak tracing module is used to identify suspicious key combinations used in advance decryption based on the matching assessment results, issue an alarm, and verify the member that stores any subkey in the suspicious key combination;

[0050] The sequential decryption module is used to input any subkey as the activation key within the time window allowed for bid opening, generate the input order of subsequent subkeys according to the input time of the activation key, and decrypt the encrypted bid according to the subkey input order.

[0051] After encrypting the real electronic bid document, an encrypted bid document is generated. The master key of the encrypted bid document is K. The master key K is split using a threshold encryption scheme. The threshold encryption scheme is (k,n), where n is the total number of subkeys into which the master key K is split, and k is the minimum number of subkeys required to reconstruct the master key K. Any k subkeys can restore the master key K. The subkeys generated by the split are saved separately by the bidding team members, and each subkey is held by a unique member.

[0052] The bid derivation module is used to create false information. The method of generating surface bids based on real electronic bids is as follows:

[0053] Define the real electronic bid as Pt, which contains the real quotation Qt. Then the method for generating the surface bid is Pf = Mask(Pt, Qf), where the surface bid is Pf, the false quotation is Qf, and Mask() is the masking transformation. The expression formula of the masking transformation is Where H() is the hash function, is a bitwise XOR operation, || is used to concatenate multiple inputs into one hash input, and Salt is a random salt value;

[0054] It should be noted that the surface bid modifies the quotation field, but keeps the format, terms, and technical parameters of the real bid unchanged. Slight disturbances are introduced in the non-quotation fields to prevent the real bid from being inferred through text comparison. That is, the surface bid and the real bid have the same format but different quotations.

[0055] The logic for obtaining false quotes from surface-level tenders is as follows:

[0056] Calculate the hash value for each subkey combination Ki that meets the threshold requirement. The calculation expression is Hi = H(Ki), where Hi is the hash value of the subkey combination Ki and H(Ki) is the unique identifier for the hash calculation of the subkey combination Ki.

[0057] For each subkey combination Ki that meets the threshold requirement, the basic perturbation value Bpv is calculated using the hash value Hi. The calculation expression is Bpv = rand(Hi) mod R, where rand(Hi) is a random number generated based on Hi, R is the perturbation range, and mod is the modulus value. Mod R is used to constrain the perturbation result to the range [0, R-1].

[0058] Then the calculation expression of false quotation is Qf=Qt+Bpv;

[0059] It should be noted that the false quotation obtained based on the hash function and random perturbation term is an irreversible hash mapping, which ensures that the false quotation obtained in advance decryption for different sub-key combinations is different. The secure hash function ensures that the quotation corresponding to each key combination is unique, and the modulus value controls the amplitude of the quotation change. The random perturbation term is used to prevent attackers from inferring the key through hashing. The specific settings of the hash coefficient and perturbation range are set by professional and technical personnel in this field.

[0060] Specifically, if the threshold encryption scheme splits the master key of the encrypted bid document into (3,5), the total number of subkeys is 5, and the minimum number of subkeys required to reconstruct the master key K is 3, then the subkey combination-false bid mapping is as follows:

[0061] Subkey combination (Ki) Hash value Hi Basic disturbance value Bpv False Quote Qf {k1,k2,k3} H1 +2.3％ 1.023 million {k1,k3,k5} H2 -1.8％ 982,000 {k3,k4,k5} H3 +0.5％ 1.005 million … … … …

[0062] Table 1 Subkey combination-false quotation mapping

[0063] Since electronic bidding systems typically only allow one bid to be uploaded, it's not possible to simply submit a fake bid and retain the real one. The surface bid is a disguised version of the real bid. It appears identical to a regular bid, but the core price is fake. Before the bid opening, anyone who decrypts the bid in advance cannot obtain the real price, only the fake one. This prevents competitors from exploiting the bid. Anyone who steals the bid during storage or transmission only sees the surface bid, without affecting the decryption of the real bid. Generating the surface bid based on the real bid effectively improves the electronic bid's anti-leakage capabilities. Even if the encryption is cracked, it provides additional camouflage protection, effectively preventing competitors from illegally adjusting their bids in advance. Different subkey combinations decrypt different bids in advance. Even if a thief obtains a partial key, they cannot accurately infer the real bid. Each fake bid is uniquely bound to a key combination. By analyzing bidder bid changes, it's possible to assess whether the subkey has been compromised and track the specific source of the leak. The fake bid is not fixed but generated based on a hash function and random perturbations, effectively blocking the path to reverse engineering the real bid.

[0064] The pre-decryption verification module is used to detect abnormal bids based on the collected historical bid data of bidders. The module calculates the robustness of the bidders' bid patterns through time series analysis. Combining abnormal bid detection and bid pattern robustness, the module assesses whether the false bids in the surface bid documents have been decrypted in advance. If the encrypted bid document is determined to have been decrypted in advance, the module conducts leak tracing. If the encrypted bid document is determined not to have been decrypted in advance, the module performs bid opening decryption.

[0065] The method for detecting abnormal bids based on the collected historical bid data of bidders is as follows:

[0066] Set a bidding round time window, collect the historical bid data of the bidders within the bidding round time window, and calculate the mean and standard deviation of the historical bid data to generate a normal bid distribution. The normal bid distribution is N(μ,σ), where μ is the mean of the historical bid data. The calculation expression is: Where, X e is the bid price in the e-th round, N is the number of historical bidding rounds, σ is the standard deviation of historical bidding data, and the calculation expression is:

[0067] Set the abnormal threshold to Exth and calculate the Z score of the bidder's bid data in this round as Where X is the bidder's bid data for this round. If the Z score is greater than or equal to the abnormal threshold Exth, the bidder's bid for this round is recorded as abnormal, and the electronic bid is marked as a 1A signal. If the Z score is less than the abnormal threshold Exth, the bidder's bid for this round is recorded as normal, and the electronic bid is marked as a 1B signal.

[0068] The method for calculating the robustness of the bidding pattern of the bidders through time series analysis is:

[0069] According to the historical bidding data of the bidders, a time series is constructed as Sc={B t-v}, B t-v is the bid data of the previous v rounds, then the robustness of the bidder’s bid pattern is calculated as B t This is the quotation data of this round;

[0070] Set the strategy change threshold to Pcth. If |Gc| is greater than or equal to the strategy change threshold Pcth, the bidder's strategy for this round is recorded as abnormal, and the electronic bid document is marked as a 0A signal. If |Gc| is less than the strategy change threshold Pcth, the bidder's strategy for this round is recorded as normal, and the electronic bid document is marked as a 0B signal.

[0071] The logic for evaluating whether the false bids in the surface bid documents have been decrypted in advance by combining abnormal bid detection and bid pattern robustness is as follows:

[0072] If the electronic bid document is marked with 1A signal and 0A signal, the electronic bid document signal is updated to 00 signal. The bidder's bid is abnormal and the bidding strategy has suddenly changed. The bidder's bid and each false bid are analyzed for correlation to determine the leaked false bid.

[0073] If the electronic bid document is marked as 1A signal and 0B signal, the electronic bid document signal is updated to 10 signal. The bidder's bid is abnormal and the bidding strategy is stable. No correlation analysis is performed between the bidder's bid and each false bid.

[0074] If the electronic bid document is marked with a 1B signal and a 0A signal, the electronic bid document signal is updated to a 01 signal. The bidder's bid is normal and the bidding strategy has changed suddenly. No correlation analysis is performed between the bidder's bid and each false bid.

[0075] If the electronic bid document is marked as 1B signal and 0B signal, the electronic bid document signal is updated to 11 signal. The bidder's quotation is normal and the quotation strategy is stable. No correlation analysis is performed between the bidder's quotation and each false quotation.

[0076] The method for analyzing the correlation between bidders' quotations and each false quotation and identifying leaked false quotations is as follows:

[0077] The correlation between the bidder's bid and each false bid is calculated using the Pearson correlation coefficient. The calculation expression is: Where r is the correlation between the bidder's bid and each false bid, is the covariance between the bidder's bid and each false bid, and the calculation expression is M is the total number of historical bidding quotation data, is the bid price of the jth bidder, is the false bid generated by the subkey combination Ki in the j-th bidding, σB comp is the standard deviation of the bidder's quotation, and the calculation expression is in, is the average of historical bidders’ quotations, and the calculation expression is: is the standard deviation of false quotes, and the calculation expression is is the mean of false quotes, and the calculation expression is

[0078] The correlation threshold is set to Rth. When the calculated Pearson correlation coefficient r is greater than or equal to the correlation threshold Rth, the false quotation is marked as a relevant quotation, and it is recorded that the false quotation has a leakage risk. When the calculated Pearson correlation coefficient r is less than the correlation threshold Rth, the false quotation is marked as an irrelevant quotation, and it is recorded that the false quotation has no leakage risk.

[0079] If there is a false quotation with a risk of leakage, the subkey combination corresponding to the false quotation is determined through the subkey combination-false quotation mapping, and the subkey combination is marked as a suspicious key combination. The administrator of the electronic bid document multi-layer encryption system is warned to verify the holder of the subkey in the suspicious key combination;

[0080] If there is no false quotation with a risk of leakage, then within the time window allowed for the bid opening, any sub-key is input as the activation key, and the input order of subsequent sub-keys is generated according to the input time of the activation key, and the encrypted bid is decrypted according to the sub-key input order.

[0081] After the activation key is entered, the input timestamp is recorded to ensure that the decryption order is generated based on the dynamic timestamp. The hash function is used to calculate the input order of subsequent subkeys. The calculation expression is Seed = H(T0, Kinit) mod n, where Kinit is the activation key, T0 is the activation key input timestamp, H() is the hash function, n is the total number of subkeys, mod is the modulus value, and modn ensures that the generated index is within the key range. Seed is the seed value used to generate the key input order. The input order of subsequent subkeys is then P = Permute({1,2,...,n},Seed), where Permute() is a random permutation function. The remaining k-1 subkeys are input in sequence according to the input order P of the subsequent subkeys to decrypt the encrypted bid.

[0082] If the subkeys are entered in the correct order and the subkey combination meets the threshold scheme requirements, the authentic electronic bid document will be decrypted;

[0083] If the subkeys are entered in the wrong order, the decrypted document will be the surface document, and the real electronic document cannot be obtained.

[0084] Permute() is used to rearrange the subkey order based on Seed, ensuring that the order of input subkeys is unpredictable.

[0085] Traditional methods usually require the collection of sufficient subkeys for decryption. Therefore, as long as some subkeys are leaked, attackers can decrypt in advance and obtain the real electronic bid content. Even if threshold encryption is adopted, once the threshold requirement is met, the decryption process is still fixed, and attackers can use the subkeys obtained in advance for offline decryption. However, the encryption method provided by this application is not enough to obtain enough subkeys for decryption. It is necessary to input the keys in the correct time window and in accordance with the dynamically generated key input sequence to successfully decrypt. Even if some subkeys are leaked, it is difficult to obtain the correct key input sequence before the bid opening time, making it impossible to decrypt in advance. Traditional methods usually rely on static keys, that is, the key itself is fixed and does not change with time. Once If the key is leaked, it can be decrypted at any time without being restricted by the bid opening time limit. This application calculates the sub-key sequence by activating the key input time, so that the decryption sequence changes dynamically. Traditional encryption methods are generally unable to detect sub-key leakage because attackers can secretly decrypt data without leaving any traces. Even if there is a risk of early decryption, the specific leaked sub-key cannot be traced back because the functions of all sub-keys are equivalent. This application adopts the design of surface bids combined with associated key combinations. Each sub-key combination corresponds to a different false quotation. Early decryption can only obtain a false quotation. After the bid opening, by analyzing the bid quotations of other bidders, the leaked sub-key combination can be effectively traced, thereby locking the potential leakage path.

[0086] The above formulas are all dimensionless and numerical calculations. The formulas are obtained by collecting a large amount of data and performing software simulation to obtain the most recent real situation. The preset parameters in the formulas are set by technicians in this field according to actual conditions.

[0087] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working process of the system described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0088] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. The multi-layer encryption system for electronic tender documents is characterized by: It includes key splitting module, false quotation generation and binding module, advance decryption verification module, leakage tracing module, and sequential decryption module; The key splitting module is used to encrypt the real electronic bid document to generate an encrypted bid document, split the master key using a threshold encryption scheme, and transmit the resulting subkeys to several members of the bidding team for storage; The fake bid generation and binding module is used to combine hash functions and random perturbations to generate a surface bid based on the real electronic bid. It calculates the fake bid of the surface bid based on the different subkey combinations used for pre-decryption and generates a subkey combination-false bid mapping. The pre-decryption verification module is used to detect abnormal bids based on the collected historical bid data of bidders. The module calculates the robustness of the bidders' bid patterns through time series analysis. Combining abnormal bid detection and bid pattern robustness, the module assesses whether the false bids in the surface bid documents have been decrypted in advance. If the encrypted bid document is determined to have been decrypted in advance, the module conducts leak tracing. If the encrypted bid document is determined not to have been decrypted in advance, the module performs bid opening decryption. The leak tracing module is used to identify suspicious key combinations used in advance decryption based on the matching assessment results, issue an alarm, and verify the member that stores any subkey in the suspicious key combination; The sequential decryption module is used to input any subkey as the activation key within the time window allowed for bid opening, generate the input sequence of subsequent subkeys based on the input time of the activation key, and decrypt the encrypted bid document according to the input sequence of the subkeys; The method of generating a surface tender document based on a real electronic tender document is as follows: Define the real electronic bid as Pt, which contains the real quotation Qt. Then the method for generating the surface bid is Pf=Mask(Pt,Qf), where the surface bid is Pf, the false quotation is Qf, Mask() is the masking transformation, and the expression formula of the masking transformation is , where H() is the hash function, is a bitwise exclusive OR operation, Used to concatenate multiple inputs into one hash input, Salt is a random salt value; The logic for obtaining false quotes from surface-level tenders is as follows: Calculate the hash value for each subkey combination Ki that meets the threshold requirement. The calculation expression is Hi=H(Ki), where Hi is the hash value of the subkey combination Ki and H(Ki) is the unique identifier for the hash calculation of the subkey combination Ki. For each subkey combination Ki that meets the threshold requirement, the basic perturbation value Bpv is calculated using the hash value Hi. The calculation expression is Bpv = rand(Hi) mod R, where rand(Hi) is a random number generated based on Hi, R is the perturbation range, and mod is the modulus value. Mod R is used to constrain the perturbation result within the range. Then the calculation expression of false quotation is Qf=Qt+Bpv; The method for analyzing the correlation between bidders' quotations and each false quotation and identifying leaked false quotations is as follows: The correlation between the bidder's bid and each false bid is calculated using the Pearson correlation coefficient. The calculation expression is: , where r is the correlation between the bidder's bid and each false bid, is the covariance between the bidder's bid and each false bid, and the calculation expression is , M is the total number of historical bidding quotation data, is the bid price of the jth bidder, is the false bid generated by the subkey combination Ki in the j-th bidding, is the standard deviation of the bidder's quotation, and the calculation expression is ,in, is the average of historical bidders’ quotations, and the calculation expression is: , is the standard deviation of false quotes, and the calculation expression is , is the mean of false quotes, and the calculation expression is ; The correlation threshold is set to Rth. When the calculated Pearson correlation coefficient r is greater than or equal to the correlation threshold Rth, the false quotation is marked as a relevant quotation, and it is recorded that the false quotation has a leakage risk. When the calculated Pearson correlation coefficient r is less than the correlation threshold Rth, the false quotation is marked as an irrelevant quotation, and it is recorded that the false quotation has no leakage risk.

2. The electronic tender document multi-layer encryption system according to claim 1, characterized in that: The method of splitting the master key using the threshold encryption scheme is: After encrypting the real electronic bid, an encrypted bid is generated. The master key of the encrypted bid is K. The master key K is split using a threshold encryption scheme. The threshold encryption scheme is (k,n), where n is the total number of subkeys into which the master key K is split, and k is the minimum number of subkeys required to reconstruct the master key K. The master key K can be restored by any k subkeys.

3. The electronic tender document multi-layer encryption system according to claim 1, characterized in that: The method for detecting abnormal bids based on the collected historical bid data of bidders is as follows: Set a bidding round time window, collect the historical bid data of the bidders within the bidding round time window, and calculate the mean and standard deviation of the historical bid data to generate a normal bid distribution. The normal bid distribution is N(μ,σ), where μ is the mean of the historical bid data. The calculation expression is: , where is the bid price in the e-th round, N is the number of historical bidding rounds, σ is the standard deviation of historical bidding data, and the calculation expression is: ; Set the abnormal threshold to Exth and calculate the Z score of the bidder's bid data in this round as , where X is the bidder's bid data for this round. If the Z score is greater than or equal to the abnormal threshold Exth, the bidder's bid for this round is recorded as abnormal, and the electronic bid is marked as a 1A signal. If the Z score is less than the abnormal threshold Exth, the bidder's bid for this round is recorded as normal, and the electronic bid is marked as a 1B signal.

4. The electronic tender document multi-layer encryption system according to claim 1, characterized in that: The method for calculating the robustness of the bidding pattern of the bidders through time series analysis is: The time series is constructed based on the historical bidding data of the bidders: , is the bid data of the previous v rounds, then the robustness of the bidder’s bid pattern is calculated as , This is the quotation data of this round; Set the strategy change threshold to Pcth. If If the strategy change threshold Pcth is greater than or equal to the strategy change threshold, the bidder’s strategy in this round is recorded as abnormal and the electronic bid document is marked as 0A signal. If it is less than the strategy change threshold Pcth, the bidder's strategy for this round is recorded as normal, and the electronic bid document is marked as a 0B signal.

5. The electronic tender document multi-layer encryption system according to claim 4, characterized in that: The logic for evaluating whether the false bids in the surface bid documents have been decrypted in advance by combining abnormal bid detection and bid pattern robustness is as follows: If the electronic bid document is marked with 1A signal and 0A signal, the electronic bid document signal is updated to 00 signal. The bidder's bid is abnormal and the bidding strategy has suddenly changed. The bidder's bid and each false bid are analyzed for correlation to determine the leaked false bid. If the electronic bid document is marked as 1A signal and 0B signal, the electronic bid document signal is updated to 10 signal. The bidder's bid is abnormal and the bidding strategy is stable. No correlation analysis is performed between the bidder's bid and each false bid. If the electronic bid document is marked with a 1B signal and a 0A signal, the electronic bid document signal is updated to a 01 signal. The bidder's bid is normal and the bidding strategy has changed suddenly. No correlation analysis is performed between the bidder's bid and each false bid. If the electronic bid document is marked with a 1B signal and a 0B signal, the electronic bid document signal is updated to a 11 signal. The bidder's bid is normal and its bidding strategy is stable. No correlation analysis is performed between the bidder's bid and each false bid. The 1A signal indicates that the Z score of the bidder's current round of bids is greater than or equal to the abnormal threshold Exth, where the calculation expression of the Z score is: , where The bid data of this round of bidding. is the mean of historical quote data, is the standard deviation of historical quote data; The 1B signal indicates that the Z score of the bidder's bid in this round is less than the abnormal threshold Exth.

6. The electronic tender document multi-layer encryption system according to claim 1, characterized in that: If there is a false quotation with a risk of leakage, the subkey combination corresponding to the false quotation is determined through the subkey combination-false quotation mapping, and the subkey combination is marked as a suspicious key combination. The administrator of the electronic bid document multi-layer encryption system is warned to verify the holder of the subkey in the suspicious key combination; If there is no false quotation with a risk of leakage, then within the time window allowed for the bid opening, any sub-key is input as the activation key, and the input order of subsequent sub-keys is generated according to the input time of the activation key, and the encrypted bid is decrypted according to the sub-key input order.

7. The electronic tender document multi-layer encryption system according to claim 6, characterized in that: After the activation key is entered, the input timestamp is recorded to ensure that the decryption order is generated based on the dynamic timestamp. The hash function is used to calculate the input order of subsequent subkeys. The calculation expression is Seed = H (T0, Kinit) mod n, where Kinit is the activation key, T0 is the activation key input timestamp, H () is the hash function, n is the total number of subkeys, mod is the modulus value, and mod n ensures that the generated index is within the key range. Seed is the seed value used to generate the key input order. The input order of subsequent subkeys is P = Permute ({1, 2, ..., n}, Seed), where Permute () is a random permutation function. The remaining k-1 subkeys are input in sequence according to the input order P of the subsequent subkeys to decrypt the encrypted bid. If the subkeys are entered in the correct order and the subkey combination meets the threshold scheme requirements, the authentic electronic bid document will be decrypted; If the subkeys are entered in the wrong order, the decrypted document will be the surface document, and the real electronic document cannot be obtained.

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