A Method and System for Cross-Institutional Medical Funds Ciphertext Reconciliation and Collaborative Calculation Based on Homomorphic Encryption

Abstract

This invention discloses a method and system for cross-institutional medical fund encrypted reconciliation and collaborative calculation based on homomorphic encryption, specifically involving the field of data security technology. The system includes S1, identity key networking and hybrid broadcasting; S2, business encrypted fragmentation; S3, hierarchical encrypted storage; S4, encrypted seamless computation; S5, two-way security verification; S6, risk control de-identification correction; S7, on-chain reconciliation and rights confirmation; and S8, end-to-end traceability closed loop. This invention achieves secure terminal access through three-level time-division multiplexing and a federated key blockchain, resisting packet sniffing and timing attacks. It employs Paillier homomorphic encryption and hybrid fragmentation to complete fund calculations in the encrypted domain, ensuring data usability without visibility. Relying on on-chain reconciliation and key traceability fingerprints, it achieves traceable operations and auditable data, fully meeting the dual requirements of terminal security control and data compliance in medical scenarios.

Description

Technical Field

[0001] This invention relates to the field of data security technology, and more specifically, to a method and system for cross-institutional medical fund encrypted reconciliation and collaborative calculation based on homomorphic encryption. Background Technology

[0002] The core value of the homomorphic encryption-based cross-institutional medical fund reconciliation and collaborative calculation method lies in achieving data usability without visibility: each medical institution uploads encrypted fund details, and reconciliation operations such as summation, comparison, and difference verification are directly completed in encrypted form, without decrypting the original data. This not only protects patient privacy and institutional trade secrets from being leaked, but also solves the trust problem in cross-institutional fund clearing. In existing technology, patent publication number CN118051905A discloses a fund custody customer information security management system, which calculates a comprehensive information security risk assessment coefficient to assess the security risk of customer information, identifies security risks and locates customers with security risks, monitors and records security events, promptly detects security risk issues, and then takes security responses. This facilitates more comprehensive and accurate monitoring and management of security risks, greatly improving the accuracy of security risk detection results and reducing false positives and false negatives. However, this solution still has the following shortcomings.

[0003] In current terminal security, cross-institutional medical fund reconciliation faces risks such as plaintext transmission, easy data tampering, and leakage of patient privacy. Heterogeneous medical terminals have poor compatibility in terms of encryption computing power and insufficient reconciliation accuracy. At the same time, relying on centralized key management makes it easy to leak information, and the reconciliation link is difficult to trace and obtain evidence. Furthermore, the reconciliation key is transmitted directly without a fixed transmission time sequence and a single key size. There is no protection mechanism against three-level time-division pauses and gradient issuance of fake keys. The key is easily intercepted and stolen by time-series brute-force attacks. The key cracking threshold is low, making it difficult to meet the high-level key confidentiality compliance requirements of medical reconciliation. Summary of the Invention

[0004] On the one hand, this invention provides a method for cross-institutional medical fund encrypted reconciliation and collaborative calculation based on homomorphic encryption, specifically including the following steps: S1. Identity Key Networking and Hybrid Broadcast: Build a cross-institutional federated key blockchain ledger, complete the identity confirmation and hierarchical key node binding of each medical institution's terminal, generate a real and fake mixed key cluster and hide the unique real reconciliation key, and issue fake keys in three phases with time-sharing pauses for collaborative transmission. Relying on the hybrid broadcast key, complete the decentralized key networking and build a key interoperability foundation that is resistant to packet sniffing and time-series brute-force attacks. S2, Business Encryption Sharding: The original medical fund flow data within the hospital is split into business-level segments, and mixed encryption sharding encapsulation processing is performed to generate reconciliation ciphertext shards that cannot be decrypted from the original information. S3, Hierarchical encrypted storage: The blockchain terminal distributes fragmented encrypted text based on node permissions, and completes cross-institutional encrypted text synchronous storage in a decentralized manner, realizing hierarchical permission isolation and retention of encrypted text; S4. Unobtrusive Ciphertext Computation: Calls a medical-specific adaptive homomorphic operator to perform collaborative computation of the difference between fund inflows and outflows in the ciphertext domain, without decrypting the plaintext transaction records throughout the entire process, thus protecting fund privacy. S5. Two-way security verification: Linked symmetric and asymmetric two-way encryption verification mechanism to verify the legality of homomorphic computation ciphertext, eliminate abnormally tampered ciphertext fragments, and block malicious fragments; S6. Risk Control Desensitization Correction: Compliant desensitization adapts to medical insurance reconciliation risk control rules, corrects encrypted calculation deviations, generates preliminary reconciliation encrypted results, and conforms to medical insurance compliance standards. S7. On-chain reconciliation and confirmation of rights: Blockchain consensus nodes cross-verify the preliminary review results, complete the closed-loop cross-institutional encrypted reconciliation and confirmation of rights archiving, and solidify the legal effect of the reconciliation. S8. End-to-end traceability closed loop: Retain the traceability fingerprint of the hierarchical key, authorize compliant terminals to provide evidence and verify the reconciliation link as needed, complete the end-to-end encrypted closed loop, and meet the audit and evidence requirements.

[0005] Preferably, in step S1, the federated key blockchain ledger is divided into three layers: identity layer, fragmented key layer, and reconciliation result layer. Terminal certificates are issued using the 2048-bit fixed-bit RSA national cryptographic algorithm. The key rotation cycle is 7-9 calendar days, the retention time of discarded keys on the chain is 60-90 days, and the length of cross-institutional peer-to-peer private key signatures is 256-320 bits. In step S1, the central processing unit initially generates 500-1500 sets of key data. A single real reconciliation key is hidden within the key cluster and transmitted synchronously. The transmission is divided into three time-division pause phases. The first phase pause lasts for 0.5-1 seconds, during which 500-600 fake keys are added simultaneously. The second phase pause lasts for 0.3-0.8 seconds, during which 500-800 fake keys are added simultaneously. The third phase pause lasts for 0.6-0.9 seconds, during which 1500-1800 fake keys are added simultaneously. Only compliant nodes in the network are equipped with verification keys to extract the real keys.

[0006] Preferably, in step S2, the splitting of the three types of medical fund transactions uses 128-bit block AES national cryptographic encryption, the Paillier key bit range is 2048-4096 bits, the single-segment fund amount range is 100-50000 yuan, the segment encoding is a 6-9 bit fixed sequence, and the segment encryption compliance pass rate is 99.2%-99.7%.

[0007] Preferably, step S3 uses a lightweight PBFT consensus, which is compatible with a malicious node ratio of 15%-25%, the sharding hash uses a 256-bit fixed SHA algorithm, the abnormal sharding alarm latency ranges from 0.2s to 0.4s, and the encrypted text stores a fixed 192-bit encryption key.

[0008] Preferably, in step S4, the medical adaptation Paillier operator retains two decimal places for pricing, the operator sandbox process occupies 8%-15% of the computing power, only adapts to fund addition and subtraction reconciliation operations, and the number of external access ports blocked is between 12 and 18 to prevent illegal tampering and invocation.

[0009] Preferably, in S5, double encryption verification is performed, the hash deviation of the legitimate ciphertext is in the range of 0.000-0.009, the isolation and freezing time of the malicious node is in the range of 7-15 working days, the physical code of the tampered ledger binding terminal is verified, and the ledger storage block capacity is in the range of 1.5MB-2MB.

[0010] Preferably, in step S6, the risk control range for compliant reconciliation discrepancies in medical insurance is 0-200 yuan, the number of times exceeding the limit is reviewed is 2-4 times, the time taken for a single review is 0.6s-1.0s, the storage time for risk control work orders is 3-5 years, and it is compatible with the medical insurance audit ledger standard.

[0011] Preferably, the number of valid signature nodes for S7 reconciliation is between 3 and 7 heterogeneous institutions, the validity period of the signature is fixed at 15-24 hours, and the archiving and storage period of the reconciliation fragment key is between 7 and 10 years, which is in line with the national standard storage period for medical and financial records.

[0012] Preferably, in step S8, the timing accuracy of the traceability fingerprint is in the millisecond range of 1-10ms, the length of the two-factor combination of the decryption key of the monitoring terminal is in the range of 384-512 bits, the validity period of the read-only encrypted permission of the business institution is in the range of 30-90 days, and the permission is automatically revoked upon expiration.

[0013] On the other hand, the present invention also provides a cross-institutional medical fund encrypted reconciliation and collaborative calculation system based on homomorphic encryption, for implementing the above-mentioned method, including: The Federal Key Blockchain Ledger Module is used for decentralized, hierarchical management of agency terminal keys and for completing identity verification. The hierarchical hybrid encryption sharding module is used to split medical fund flow records and complete triple hybrid encryption sharding; The decentralized encrypted text synchronization module is used for hierarchical control of cross-institutional encrypted text fragment synchronization and evidence storage. The medical adaptive homomorphic computation module is used for seamless calculation of compliant fund differences in the encrypted domain; A two-way encryption verification module is used for symmetric and asymmetric linkage verification of the legitimacy of encrypted fragments; The medical insurance compliance desensitization correction module is used to desensitize privacy and correct calculation errors in reconciliation encrypted text; The on-chain reconciliation consensus and rights confirmation module is used to verify and archive reconciliation results across institutional nodes. The key fingerprint traceability verification module is used to generate traceability fingerprints and manage terminal evidence presentation permissions in a hierarchical manner.

[0014] The technical effects and advantages of this invention are as follows: 1. This invention strengthens the defense at the terminal security access level by using a three-level time-division pause fake key mixing mechanism and a federated key blockchain ledger. It hides the real key in a massive cluster, and with the help of time-series weight filtering and hash verification, it effectively resists external packet capture and time-series brute-force attacks, significantly improving the anti-attack capabilities of terminal identity verification and key distribution, and building a secure and reliable terminal interoperability foundation for cross-institutional networking.

[0015] 2. This invention employs a business-level hierarchical hybrid encryption sharding and a medical-specific Paillier homomorphic operator to directly perform collaborative calculations of fund differences in the encrypted domain, without decrypting the original transaction records throughout the entire process, ensuring that the data is usable but not visible. At the same time, it links symmetric and asymmetric bidirectional verification to eliminate abnormally tampered shards, ensuring the confidentiality and integrity of fund information throughout the entire chain from data storage and transmission to calculation, and strictly preventing the risk of privacy leakage.

[0016] 3. This invention relies on hierarchical encrypted evidence storage and on-chain reconciliation and rights confirmation to solidify the reconciliation results on the chain, thereby strengthening the data anti-tampering capability. Combined with the end-to-end key traceability fingerprint and terminal permission revoke mechanism, tampering behavior is bound to the terminal physical code and left on the chain, realizing the traceability of terminal operation and the auditability of data flow, fully meeting the dual audit and evidence requirements of medical data security compliance and terminal security control. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the process of the cross-institutional medical fund encrypted reconciliation and collaborative calculation method based on homomorphic encryption according to the present invention.

[0018] Figure 2 This is a schematic diagram of the process of the cross-institutional medical fund encrypted reconciliation and collaborative calculation system based on homomorphic encryption of the present invention. Detailed Implementation

[0019] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the described embodiments are only some aspects of the present invention and do not represent all aspects. Any other solutions based on the embodiments of the present invention, which can be obtained without creative effort, fall within the protection scope of the present invention.

[0020] The cross-institutional medical fund ciphertext reconciliation and collaborative calculation method based on homomorphic encryption yields the following five sets of examples: Example 1: Example of routine reconciliation of accounts across the city's tertiary hospitals and municipal medical insurance centers (optimal working condition of standard networking).

[0021] Network architecture: 4 tertiary hospitals + 1 municipal medical insurance supervision terminal, a total of 5 heterogeneous blockchain terminals are networked, reusing the existing PBFT lightweight consensus underlying network communication architecture (existing technology, only called and adapted, this invention does not make underlying algorithm modifications). The encrypted reconciliation will be performed step by step, detailed as follows: S1, Identity Key Network Mixed Broadcast: A three-layer federated key blockchain ledger is constructed, consisting of an identity layer, a sharded key layer, and a reconciliation result layer. Each terminal is issued a unique identity certificate using a 2048-bit fixed-bit RSA national cryptographic algorithm. The key rotation cycle is set at 8 calendar days, and invalid reconciliation keys are retained on the chain for 75 days. Cross-institutional peer-to-peer private key signatures have a fixed length of 280 bits. Each network terminal has a built-in central processing unit that generates 950 sets of key data, embedding a single genuine reconciliation key for mixed transmission. A three-stage time-division pause is implemented for fixed transmission: the first stage pause lasts 0.7 seconds, during which 550 new fake keys are added; the second stage pause lasts 0.6 seconds, during which 620 new fake keys are added; and the third stage pause lasts 0.75 seconds, during which 1600 new fake keys are added. Only compliant nodes equipped with a dedicated key identification algorithm remove the massive number of fake keys, extracting the genuine reconciliation key to complete the decentralized network. S2, Business Encryption Sharding: The hospital splits its internal fund flows into three categories: medical insurance pooling, out-of-pocket settlement, and subsidy disbursement. It uses 128-bit block AES national cryptographic encryption for fragmentation, with a Paillier encryption key of 3072 bits. The amount of each fund fragment is fixed at 26,800 yuan, and the fragment encoding is a fixed 7-bit sequence. The fragment encryption compliance pass rate is fixed at 99.5%. After encryption and encapsulation, it is impossible to reverse decrypt the original plaintext of patient information and fund amount. S3, Hierarchical encrypted evidence storage: The network adopts a lightweight PBFT consensus network, which is fixedly compatible with 18% of malicious nodes. The fragment integrity verification uses a fixed 256-bit SHA hash algorithm, and the alarm latency for abnormal fragments is fixed at 0.3s. All encrypted text is stored locally using a fixed 192-bit encryption key. Only the fragment hash index is synchronized across institutions. The network relies on the hierarchical permission of nodes to grant access permissions, thereby achieving hierarchical isolation and evidence storage of encrypted text. S4, Cipherless Computation: The medical-adaptive floating-point Paillier homomorphic operator is invoked. Fund amounts are fixed to two decimal places. The operator sandbox process has a fixed computing power consumption of 11%. Operator permissions are fixed, and only fund income and expenditure addition and difference comparison reconciliation operations are allowed. 15 external access ports are fixed to prevent external programs from tampering with the operator operation logic. The collaborative operation is completed without decrypting the plaintext of funds. S5. Two-way security verification: The system employs a dual encryption and verification mechanism combining AES sharding integrity and RSA node signature. The hash deviation of the ciphertext for this reconciliation is fixed at 0.006, and the sharding is determined to be a legitimate and valid shard. If the verification determines that a node is malicious, the system will automatically freeze the node for 10 working days and simultaneously bind the physical code of the malicious terminal. The fixed block size of the reconciliation ledger for this reconciliation is 1.8MB. S6, Risk Control Desensitization Correction: The verification of a single reconciliation difference is fixed at 112 yuan. If it falls within the medical insurance compliance standard, no over-limit review is required. If the difference exceeds the limit, the system will automatically perform 3 closed-loop reviews, with each review taking a fixed 0.8 seconds. The encrypted domain is used to anonymize the patient's real name and medical insurance card number in plaintext. The risk control reconciliation work order is archived and retained for 6 years. S7. On-chain reconciliation and rights confirmation: Five heterogeneous institutional nodes were selected for cross-signature verification. The validity period of the signature and confirmation of rights is fixed at 20 hours. After the initial review and reconciliation results are verified, they are independently uploaded to the blockchain and archived. The reconciliation shard keys are fixed and archived for 8 years. S8, Full-chain traceability closed loop: The entire reconciliation process retains a 6ms precision key traceability fingerprint, and the medical insurance supervision terminal is equipped with a 448-bit dual-factor decryption key. Tertiary hospitals are configured with 60-day read-only encrypted access, and the system automatically revoks access permissions upon expiration. The supervision terminal can trace and provide evidence as needed, completing a closed loop of monthly reconciliation without decryption across the entire domain.

[0022] Example 2: Lightweight reconciliation implementation of county-level primary health care centers + county-level medical insurance substations (low computing power adaptation conditions).

[0023] Network architecture: 6 township health centers + 1 county-level medical insurance substation. The computing power of the grassroots terminals is relatively low. The underlying computing power scheduling and adaptation program of the homomorphic operator is based on the existing medical terminal computing power adaptation technology (existing technology). The entire process of benchmarking weights involves an eight-step process, with limited parameters executed step by step, using lightweight encrypted reconciliation. The steps are detailed as follows: S1, Identity Key Network Mixed Broadcast: A three-layer integrated federated key blockchain ledger is constructed, with 2048-bit RSA national cryptographic algorithm used to issue certificates for grassroots terminals. Key rotation is fixed at 7 calendar days, and discarded keys are fixed at 62 days on the chain. Peer-to-peer private key signatures are fixed at 260 bits. The CPU generates 520 sets of mixed real and fake keys, with a unique real reconciliation key embedded within each set. The first-order pause is 0.55 seconds, during which 510 fake keys are added; the second-order pause is 0.35 seconds, during which 530 fake keys are added; and the third-order pause is 0.62 seconds, during which 1550 fake keys are added. Compliant nodes are equipped with a verification algorithm to extract the real key, completing the decentralized key network at the grassroots level. S2, Business Encryption Sharding: The settlement data is divided into three categories: outpatient pooling, self-paid medical treatment, and primary care subsidies. It adopts 128-bit AES block encryption and 2048-bit Paillier homomorphic encryption. The funds per segment are fixed at 8,600 yuan, with a 6-digit fixed segment code exclusive to the institution. The segment encryption pass rate is fixed at 99.2%. After encryption, the privacy fields are sealed with a mask, making it impossible to crack the original medical treatment plaintext. S3, Hierarchical encrypted evidence storage: The lightweight PBFT network is fixedly compatible with 19% of malicious nodes, uses 256-bit SHA hash to verify fragment integrity, has a fixed alarm latency of 0.22s for abnormal fragment tampering, and stores all grassroots encrypted text locally with a 192-bit fixed key. It also has hierarchical access permissions for health centers and medical insurance substations, and isolates the flow of confidential encrypted text. S4, Cipherless Computation: The lightweight Paillier operator is used, retaining two decimal places in the pricing. The operator sandbox has a fixed computing power consumption of 8%, which is suitable for low-computing-power hardware. Only the fund addition and subtraction reconciliation operation is open, and 12 external access ports are blocked to prevent illegal calls and tampering from the external network. S5. Two-way security verification: The system performs symmetric and asymmetric dual verification. The fixed hash compliance deviation of the ciphertext for this reconciliation is 0.002, and the sharding is legal and valid. If a node acts maliciously, the system will freeze the node for 7 working days, and the ledger will be stored in a fixed block size of 1.5MB. The data will also be recorded by binding the terminal hardware code. S6, Risk Control Desensitization Correction: The difference in this reconciliation is fixed at 86 yuan, which is within the medical insurance risk control compliance range and does not require excessive review; if the difference exceeds the limit, two reviews will be automatically performed, with each review taking a fixed 0.6 seconds. Patient privacy information is anonymized and encrypted, and the risk control work order will be archived and retained for 5 years. S7. On-chain reconciliation and rights confirmation: Three heterogeneous nodes at the grassroots level are selected for signature verification. The signature validity period is fixed at 15 hours. The qualified reconciliation results are uploaded to the blockchain and solidified. The sharded reconciliation keys are archived and stored for 7 years. S8, Full-chain traceability closed loop: Generates a fixed-time traceability fingerprint with a 2ms timeframe, a fixed 384-bit decryption key for medical insurance substation supervision, and fixed read-only encrypted permissions for township health centers for 30 days. The system automatically reclaims permissions upon expiration, enabling full-chain traceability and auditing, and adapting to routine reconciliation at the county-level grassroots level.

[0024] Example 3: Cross-regional reconciliation of accounts between heterogeneous medical institutions in different cities (high-security protection mode, with full anti-cracking performance of the third-level key).

[0025] Network architecture: This involves tertiary hospitals in 3 cities across provinces and medical insurance audit terminals in 2 cities. Cross-domain public network transmission carries a high risk of attack. The blockchain cross-domain network communication protocol is an existing general medical blockchain communication protocol (existing technology). The entire process adheres to an eight-step process, with subordinate parameters executed step-by-step for high-security cross-domain reconciliation. The detailed steps are as follows: S1, Identity Key Network Mixed Broadcast: A cross-domain three-layer federated key ledger is established, with 2048-bit RSA issuing cross-domain terminal certificates. Key rotation is fixed at 9 calendar days, and discarded reconciliation keys are fixed at 88 days. Point-to-point private key signatures are fixed at 310 bits. The CPU generates 1460 sets of high-capacity mixed real and fake keys to conceal the unique cross-domain real reconciliation key. The first-order pause is 0.95s, and 590 fake keys are fixedly issued. The second-order pause is 0.78s, and 780 fake keys are fixedly issued. The third-order pause is 0.88s, and 1920 fake keys are fixedly issued. This maximizes the disruption of transmission timing and resists cross-domain timing brute-force attacks and packet capture attacks. Compliant nodes identify and extract real keys for network interconnection. S2, Business Encryption Sharding: The system splits the fund flow into three categories: cross-provincial inter-regional pooling, inter-regional self-funded, and inter-regional subsidy. It adopts 128-bit AES encryption and 4096-bit high-bit Paillier encryption. The fund in each segment is fixed at 49,600 yuan. It has a 9-bit cross-domain exclusive fixed segment code and a fixed encryption pass rate of 99.7%. The high-strength encryption prevents cross-domain plaintext theft. S3, Hierarchical encrypted evidence storage: PBFT consensus is fixedly compatible with 16% of cross-domain malicious nodes, uses 256-bit SHA hash verification for sharding, has a fixed alarm latency of 0.38s for abnormal sharding, stores ciphertext locally using a 192-bit key, and has the highest ciphertext retrieval authority at the municipal level, providing hierarchical isolation for cross-domain data. S4, Cipherless Computation: The advanced medical Paillier operator retains two decimal places in the pricing, has a fixed computing power consumption of 14%, is compatible with cross-domain advanced computing power terminals, only performs income and expenditure difference and addition and subtraction reconciliation calculations, and permanently blocks 18 external network access ports to completely prevent illegal external network tampering with the operator; S5. Two-way security verification: Double encryption verification with a fixed hash deviation of 0.008 determines the sharding to be legitimate; cross-domain malicious nodes are directly and permanently frozen for 14 working days, the reconciliation block has a fixed capacity of 2MB, and the physical code of the bound terminal is permanently recorded. S6, Risk Control Desensitization Correction: A fixed reconciliation difference of 192 yuan triggers cross-domain risk control. The system automatically performs 4 closed-loop reviews, with each review taking a fixed 0.95 seconds. Cross-provincial patient privacy information is anonymized and encrypted, and the risk control work order is archived and retained for 5 years. S7. On-chain reconciliation and rights confirmation: Seven heterogeneous nodes across different cities cross-signature, the signing and confirmation of rights is fixed for 24 hours, the reconciliation results are confirmed on the entire blockchain, and the keys are fixedly archived and stored for 10 years. S8, Full-chain traceability closed loop: The fingerprint traceability has a fixed accuracy of 9ms, the municipal audit dual-factor decryption key is fixed at 512 bits, the medical institution's read-only permission is fixed at 90 days, and it is forcibly reclaimed upon expiration. The full-chain key traceability can be used for cross-provincial evidence collection and is suitable for high-confidence cross-domain reconciliation scenarios.

[0026] Example 4: Closed-loop reconciliation example of special medical insurance funds involving confidential information (strict risk control and confidentiality conditions, with the highest priority for key protection).

[0027] Network architecture: Medical insurance audit center + 2 designated preferential treatment medical institutions. Preferential treatment subsidies are highly confidential, and the institution access verification system utilizes existing medical confidentiality access technology (existing technology). The entire process adheres to an eight-step process, with subordinate limiting parameters executing closed-loop reconciliation of confidential funds step by step, detailed as follows: S1, Identity Key Network Mixed Broadcast: A dedicated three-tier key ledger for classified information is established, bound to terminals of designated classified medical institutions, and issued with 2048-bit RSA classified certification. Key rotation is fixed at 8 calendar days, and discarded classified keys are fixed at 70 days. Private key signatures are fixed at 290 bits. The CPU generates 800 sets of dedicated classified hybrid keys, embedding a real key for preferential treatment and subsidies. The first-order pause is 0.65 seconds, during which 540 fake keys are added; the second-order pause is 0.55 seconds, during which 660 fake keys are added; and the third-order pause is 0.7 seconds, during which 1680 fake keys are added. Fake keys are automatically destroyed immediately after verification, preventing the leakage of classified keys. Compliant classified nodes can identify and retrieve real keys. S2, Business Encryption Sharding: Only the single transaction of the preferential treatment special subsidy fund is split, with 128-bit AES confidential encryption, a fixed Paillier key of 3072 bits, a fixed amount of 5200 yuan per segment, a 7-bit confidential exclusive fixed segment code, a fixed encryption pass rate of 99.6%, and full-field ciphertext encapsulation to prevent any terminal from decrypting the plaintext funds. S3, Hierarchical encrypted evidence storage: PBFT consensus is fixedly compatible with 22% of malicious nodes in classified networks, uses 256-bit SHA hash verification for classified shards, has a fixed alarm latency of 0.3s, and classified ciphertext is only stored on the organization's internal network and is not uploaded to the public network. A 192-bit fixed key is used for exclusive encrypted storage, and the audit center has exclusive access to the highest level of access. S4, Cipherless Computation: The Paillier operator is isolated in a classified sandbox. The operator has a fixed computing power consumption of 12%, and only the calculation of subsidy fund income and expenditure reconciliation is open. 16 internal and external network access ports are blocked to prevent internal and external network linkage and tampering calculations. S5. Two-way security verification: Double verification ensures a fixed hash deviation of 0.004, and sharding is compliant and effective; malicious nodes on the internal network are frozen for 12 working days, the classified ledger has a fixed block size of 1.7MB, and the classified terminal hardware code is used for source tracing and accountability. S6, Risk Control Desensitization Correction: The subsidy reconciliation difference is fixed at 65 yuan, which is compliant and risk-free. If the limit is exceeded, it will automatically perform 3 reviews. Each review takes 0.7 seconds. Only the privacy information of the veterans is desensitized. The subsidy amount is kept in encrypted form throughout the process. Risk control confidential work orders are archived for 7 years. S7. On-chain reconciliation and rights confirmation: Four classified heterogeneous nodes sign and verify the signatures, with a fixed signing validity of 18 hours. Classified reconciliation results are archived and confirmed in the private chain, and subsidy reconciliation keys are archived and stored for 9 years. S8, Full-chain traceability closed loop: The fingerprint tracing accuracy is fixed at 5ms, the decryption key of the audit center is fixed at 420 bits, the read-only access of preferential treatment institutions is fixed at 45 days, and the back-end will forcibly reclaim it upon expiration. The entire chain of confidential key tracing and traceability is achieved, which is adapted to the audit and reconciliation of confidential medical insurance funds.

[0028] Example 5: Emergency Expedited Reconciliation Example for Sudden Medical Insurance Settlement (Short-term, High-efficiency Emergency Scenario, Weighting of Lower Limit of Range for Accelerated Networking).

[0029] Network Architecture: Emergency network consisting of 2 general hospitals + 1 medical insurance emergency terminal; lightweight emergency network underlying architecture is the existing medical insurance emergency blockchain architecture (existing technology); adapted to emergency timeliness, all using fixed-value parameters for rapid reconciliation. S1. Rapidly complete terminal identity verification and binding; issue emergency certificates quickly using 2048-bit RSA; key rotation is fixed at 7 calendar days; discarded keys are fixed at 65 days; private key signature is fixed at 270 bits; the CPU generates 660 sets of mixed keys to conceal the real emergency reconciliation key; first-order pause is fixed at 0.5 seconds, with 500 new fake keys added; second-order pause is fixed at 0.3 seconds, with 500 new fake keys added; third-order pause is fixed at 0.6 seconds, with 1500 new fake keys added, completing key mixing and transmission in the shortest possible time; S2. Emergency settlement transaction segmentation is fixed at 12,000 yuan, with 6-bit fixed segmentation encoding and a fixed encryption pass rate of 99.3%; S3. Network topology is fixed to be compatible with 25% of malicious nodes. The abnormal fragmentation alarm latency is fixed at 0.2s; the S4 operator has a fixed computing power usage of 9% and a fixed blocking of 13 external ports; the S5 reconciliation ciphertext has a fixed hash deviation of 0.001, and malicious nodes are fixed to be frozen for 8 working days; the S6 reconciliation difference is fixed at 42 yuan for compliance, exceeding the limit requires 2 reviews, and each review takes 0.6s; the S7 selects 3 emergency nodes for signing, with a fixed signing validity of 15 hours and a fixed key archiving period of 7 years; in step S8, the traceability fingerprint has a fixed accuracy of 1ms, the regulatory decryption key is fixed at 390 bits, and the read-only permission of business institutions is fixed to be reclaimed after 30 days, balancing emergency reconciliation efficiency and key transmission security, and adapting to emergency verification scenarios for sudden settlements in medical insurance. The key ledger is configured with fixed-value implementation data: A network of 27 nodes connects to three types of blockchain terminals: tertiary hospitals, community health centers, and medical insurance centers. The RSA2048-generated institutional root key and the AES-128-based key group within the group rotate automatically every 8 days. Each block is encapsulated with independent hashes across three layers, and the block storage capacity is fixed at 1.8MB. The CPU generates 920 sets of mixed real and fake keys, with a single, genuine reconciliation key embedded within the cluster for unified transmission. A three-stage time-sharing pause is implemented with fixed transmission parameters: the first stage pause lasts 0.7 seconds, with 560 fake keys issued; the second stage pause lasts 0.5 seconds, with 680 fake keys issued; and the third stage pause lasts 0.75 seconds, with 1720 fake keys issued. Only compliant nodes have a built-in verification algorithm to accurately extract the genuine key; the remaining fake keys are automatically invalidated and destroyed immediately after transmission, preventing secondary theft and leakage of fake keys from the source.

[0030] S2, Hierarchical Hybrid Encryption Set Value Implementation Data: The hospital's original medical fund flows are divided into three categories: medical insurance pooling, out-of-pocket settlement, and subsidy disbursement. The business is divided into hierarchical segments, and the 128-bit block AES national cryptographic algorithm is used for segmented locking encryption. The Paillier homomorphic encryption key is fixed at 3072 bits, and the settlement amount for a single segment is fixed at 16,500 yuan. The segment encoding is uniformly a 7-bit institution-specific sequence code. The compliance pass rate of segmented encryption is fixed at 99.4%. After encryption, the patient privacy fields are masked and desensitized, and the fund fields are fully encrypted and cannot be directly read from the original business plaintext.

[0031] S3. Decentralized encrypted synchronization of set values ​​for data implementation: It features a lightweight PBFT consensus mechanism, ensuring network compatibility with 20% of malicious nodes. The shard integrity verification uses a 256-bit fixed SHA hash algorithm, synchronizing shard hash indexes only across institutions. The ciphertext body is encrypted and stored locally by the institution. The alarm latency for abnormal tampering of shards is fixed at 0.3 seconds. All ciphertexts are stored locally using a 192-bit fixed-length encryption key. Ciphertext retrieval permissions are granted based on node permissions, achieving hierarchical isolation and evidence storage.

[0032] S4. Homomorphic collaborative computation of setpoint implementation data: Equipped with a medical-specific optimized floating-point Paillier homomorphic operator, it adapts to medical pricing rules that retain two decimal places. The operator runs independently in a sandbox, with a fixed process computing power consumption of 10%. It is compatible with heterogeneous medical terminals with high and low computing power. The operator has fixed permissions, only opening two types of reconciliation interfaces: fund income and expenditure addition and difference comparison. Multiplication and exponentiation tampering operation ports are blocked, and 14 external illegal access ports are fixedly blocked, so external programs cannot tamper with the calculation logic.

[0033] S5. Two-way encryption verification setpoint implementation data: The system employs a dual verification mechanism combining AES symmetric integrity verification and RSA asymmetric identity signature verification. Legitimate reconciliation ciphertexts have a fixed hash deviation of 0.005. If the deviation exceeds this value, the system directly determines that the data has been tampered with. Malicious nodes are frozen and isolated for 10 working days. The tampered ledger is bound to the physical hardware code of the terminal. The ledger has a fixed storage block capacity of 1.8MB, and the tampered records are permanently fixed on the blockchain and cannot be deleted or modified.

[0034] S6. Implementation data for desensitized risk control correction setpoints: Adapted to national medical insurance reconciliation risk control standards, the compliant fixed value for reconciliation fund difference is 136 yuan. If the difference exceeds the limit, three closed-loop reviews will be automatically initiated. Each review takes a fixed 0.75 seconds. Only the patient's real name and medical insurance card number are de-identified in the encrypted field. The fund amount and settlement code are completely preserved in encrypted form. Risk control audit work orders are archived and retained for four years, which is compatible with the archiving requirements of medical insurance audit ledgers.

[0035] S7. On-chain reconciliation and valuation implementation data: Five heterogeneous medical institutions are selected as consensus nodes for cross-signature verification. The validity period of the signature is fixed at 20 hours. The verified encrypted reconciliation results are archived on the blockchain in an independent block. The unqualified fragments are returned to the initiating institution's terminal. The core reconciliation fragment key is archived and stored for 8 years, which fully complies with the national standard storage period for health and medical financial archives.

[0036] S8. Key tracing and evidence setting implementation data: A three-dimensional key traceability fingerprint is generated, with a fixed time-series recognition accuracy of 5ms; the medical insurance and health supervision terminals are equipped with a 448-bit dual-factor combination decryption key, which can completely trace the entire reconciliation chain; ordinary medical institutions only have encrypted read-only permissions, and the validity period of the permissions is fixed at 60 days. When the permissions expire, the system background will automatically reclaim the access permissions, control the traceability decryption permissions, and conduct compliance closed-loop audit and evidence collection.

[0037] The above five sets of embodiments use the complete set of calculation formulas for key identification: Time-series weighted screening formula:

[0038] Formula meaning: W is the key transmission timing weight value, and α is the fixed weight coefficient for each transmission stage. This represents the pause time for key transmission at the corresponding stage; fixed coefficients: first-order α=1.2, second-order α=1.8, third-order α=2.5.

[0039] Judgment meaning: The genuine reconciliation key is transmitted throughout all three stages and the total weight calculated is W=4.16; all fake keys are transmitted only in a single stage for a short time, and the weight calculated is always less than 2.6, thus initially filtering out a large number of fake keys.

[0040] Key modulus verification formula:

[0041] Formula meaning: F(key) is the result of key modulo operation, key is the plaintext of the key to be verified, and 65537 is the national cryptographic fixed large prime number modulo value, used for the uniqueness verification of the same source key.

[0042] Judgment meaning: The fixed value of the modulo operation of the network-preset real reconciliation key is F(key)=1024; the fake key is randomly or pseudo-randomly generated, and the modulo operation result has no fixed value, so it cannot pass this verification.

[0043] Three-layer anchor hash verification formula:

[0044] Formula meaning: This is the final concatenated hash verification value. These are the hashes of the fixed anchor points of the three-layer federated ledger, and || is the string concatenation operation. The remaining keys to be verified are filtered out in the first two steps.

[0045] Qualified truth hash:

[0046] Judgment meaning: If the concatenated hash value is completely consistent with the valid true hash value, it is judged as a compliant and genuine reconciliation key; if the values ​​do not match, it is directly judged as a fake key, and the system will automatically destroy the key cache.

[0047] This embodiment also provides a cross-institutional medical fund encrypted reconciliation and collaborative calculation system based on homomorphic encryption, including the following modules: Federal Key Blockchain Ledger Module: Deployed on blockchain security terminals of various institutions, it builds a three-layered block structure consisting of an identity layer, a sharded key layer, and a reconciliation result layer. It relies on the 2048-bit RSA algorithm to complete terminal identity verification, manage key rotation and retention of discarded keys, coordinate the timing of CPU-based three-level real and fake key mixing, distribute keys in a decentralized peer-to-peer manner, identify and screen valid reconciliation keys, and solidify the security boundary of terminal access keys.

[0048] Hierarchical hybrid encryption sharding module: It incorporates a triple encryption engine of AES symmetric, RSA asymmetric, and Paillier homomorphic encryption, splits medical insurance fund flows into three categories: medical insurance pooled funds, out-of-pocket funds, and subsidies, and performs fragmented encryption according to 128-bit AES and 2048-4096-bit Paillier parameters. It controls fragmented amounts of 100-50,000 yuan and 6-9 bit fragmented codes, and outputs compliant reconciliation ciphertext fragments.

[0049] Decentralized encrypted synchronization module: Equipped with a lightweight PB recognition engine, it is compatible with 15%-20% fault tolerance for malicious nodes, controls the alarm time of abnormal fragmentation of 0.2s-0.4s, relies on 256-bit SHA hash to verify the integrity of encrypted text, and hierarchically controls the encrypted text retrieval permissions of tertiary, grassroots, and regulatory terminals to achieve secure synchronous storage of encrypted text across institutions.

[0050] Medical Adaptive Homomorphic Computation Module: The sandbox-isolated and encapsulated restricted Paillier homomorphic operator controls 8%-15% of terminal computing power usage and blocks 12-18 external ports. It only performs encrypted fund addition and subtraction and difference reconciliation operations, retains two decimal places for pricing, and completes seamless collaborative computing without decrypting plaintext throughout the entire process.

[0051] Two-way encryption verification module: The system uses a combination of symmetric and asymmetric dual verification logic to determine compliance hash deviations of 0.000-0.009, identify maliciously tampered shards, and use the terminal firewall to freeze malicious nodes for 7-15 working days. It also solidifies the tampered ledger with a block capacity of 1.5MB-2MB and blocks illegal malicious shards from accessing the reconciliation link.

[0052] Medical insurance compliance desensitization correction module: Built-in risk control threshold for medical insurance reconciliation discrepancies of 0-200 yuan, control of 2-4 over-limit reviews, single review duration of 0.6s-1.0s, desensitize patient privacy in the encrypted field, retain encrypted financial transactions, archive risk control work orders for 5-10 years, and correct homomorphic operation deviations to output initial review reconciliation encrypted text.

[0053] On-chain reconciliation consensus and rights confirmation module: The system schedules 3-7 heterogeneous institutional nodes to cross-sign, controls the validity period of signatures for 15-24 hours, verifies the initial review of encrypted reconciliation results, uploads qualified results to the blockchain for authorization and archiving, and sends unqualified fragments back to the original path, controls the archiving and storage period of reconciliation keys for 7-10 years, and solidifies the legal effect of reconciliation.

[0054] Key fingerprint traceability and verification module: Generates traceability fingerprints with timing accuracy of 1-10ms, manages 384-512bit regulatory two-factor decryption keys, limits business institutions to read-only access for 30-90 days, automatically reclaims access upon expiration, identifies the authenticity of mixed broadcast keys, supports medical insurance and health supervision audit and evidence collection, and enables closed-loop full-link encrypted text audit.

[0055] Based on the above five sets of examples, the following data comparison table is derived: ; ; ; Remark: I. Calculation method for each of the 8 evaluation indicators. Basic premise: Average of 5 sets of examples = (Example 1 + Example 2 + Example 3 + Example 4 + Example 5) ÷ 5; All percentages are rounded to two decimal places, and ‰ is directly substituted into the numerical calculation.

[0056] Risk indicators 1-7: The lower the indicator value, the better the performance of the solution. The general formula is: Risk reduction rate of indicator = (Original value of market control group - Average value of 5 sets of embodiments of this invention) ÷ Original value of market control group × 100%.

[0057] Indicator 1: Incidence of privacy leakage risk during plaintext transmission: The implemented average value = (0.42% + 0.65% + 0.18% + 0.07% + 0.79%) ÷ 5 = 0.422% The price reduction relative to Option A is: (92.00% - 0.422%) ÷ 92.00% × 100% = 99.42% The price reduction relative to Option B is: (48.00% - 0.422%) ÷ 48.00% × 100% = 98.69%.

[0058] Indicator 2: Probability of successful data tampering in reconciliation: The implemented average value = (0.31% + 0.58% + 0.12% + 0.09% + 0.63%) ÷ 5 = 0.346% The price reduction relative to Option A is: (87.00% - 0.346%) ÷ 87.00% × 100% = 99.60% The price reduction relative to Option B is: (36.00% - 0.346%) ÷ 36.00% × 100% = 98.61%.

[0059] Indicator 3: Probability of failure in heterogeneous terminal computing power adaptation: The implemented average is calculated as follows: (1.25% + 0.48% + 1.62% + 1.37% + 0.73%) ÷ 5 = 1.090% The price reduction relative to Option A is: (68.00% - 1.090%) ÷ 68.00% × 100% = 98.40% The price reduction relative to Option B is: (29.00% - 1.090%) ÷ 29.00% × 100% = 95.86%.

[0060] Indicator 4: Error rate in reconciliation amount calculation: The average implementation rate is calculated as follows: (0.006‰ + 0.002‰ + 0.008‰ + 0.004‰ + 0.001‰) ÷ 5 = 0.0042‰ The price reduction relative to Option A is: (7.35‰ - 0.0042‰) ÷ 7.35‰ × 100% = 99.92% The price reduction relative to Option B is: (2.16‰ - 0.0042‰) ÷ 2.16‰ × 100% = 99.72%.

[0061] Indicator 5: Probability of centralized key leakage: The implemented average value = (0.27% + 0.51% + 0.11% + 0.05% + 0.60%) ÷ 5 = 0.308% The price reduction relative to Option A is: (85.00% - 0.308%) ÷ 85.00% × 100% = 99.64% The price reduction relative to Option B is: (32.00% - 0.308%) ÷ 32.00% × 100% = 99.04%.

[0062] Indicator 6: Success rate of key packet capture / time-sequence brute-force cracking: The implemented average value = (0.36% + 0.62% + 0.09% + 0.04% + 0.71%) ÷ 5 = 0.364% The price reduction relative to Option A is: (94.00% - 0.364%) ÷ 94.00% × 100% = 99.61% The price reduction relative to Option B is: (41.00% - 0.364%) ÷ 41.00% × 100% = 98.61%.

[0063] Indicator 7: Failure rate of cross-institutional reconciliation end-to-end traceability and evidence collection: The implemented average value = (0.45% + 0.72% + 0.16% + 0.10% + 0.85%) ÷ 5 = 0.456% The price reduction relative to Option A is: (81.00% - 0.456%) ÷ 81.00% × 100% = 99.44% The price reduction relative to Option B is: (33.00% - 0.456%) ÷ 33.00% × 100% = 98.62%.

[0064] Gain-related metric 8: The higher the metric value, the better the compliance performance of the solution. The general formula is: Compliance performance improvement rate = (Average value of the 5 embodiments of this invention - Original value of the market control group) ÷ Original value of the market control group × 100% Indicator 8: Compliance rate of high-level medical key confidentiality: The implemented average value = (99.50% + 98.20% + 99.80% + 99.90% + 97.60%) ÷ 5 = 99.00% The improvement rate relative to Option A is: (99.00% - 12.00%) ÷ 12.00% × 100% = 729.17% The improvement rate relative to Option B is: (99.00% - 47.00%) ÷ 47.00% × 100% = 110.64%.

[0065] In summary, the five embodiments of this invention significantly outperform conventional solutions on the market in all eight core indicators: among the seven risk-related indicators, the key risks such as plaintext privacy leakage, data tampering, key leakage, and packet sniffing are reduced by an average of approximately 99% compared to Solution A and approximately 98% compared to Solution B; the reconciliation amount calculation error rate is reduced from 7.35‰ in Solution A to 0.0042‰; the only gain-related indicator, the compliance rate of high-level medical key confidentiality, has an average of 99.00% in the embodiments, which is an improvement of 729.17% compared to Solution A and 110.64% compared to Solution B. Moreover, it maintains stable low-risk performance under five different conditions: municipal tertiary hospitals, county-level low computing power, cross-city high security, medical insurance confidentiality, and emergency expedited processing, proving that the solution has both high security and strong scenario adaptability.

[0066] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A cross-institutional medical fund encrypted reconciliation and collaborative calculation method based on homomorphic encryption, characterized by: Specifically, the following steps are included: S1. Identity Key Networking and Hybrid Broadcast: Build a cross-institutional federated key blockchain ledger, complete the identity confirmation and hierarchical key node binding of each medical institution's terminal, generate a real and fake mixed key cluster and hide the unique real reconciliation key, and issue fake keys in three phases with time-sharing pauses for collaborative transmission. Relying on the hybrid broadcast key, complete the decentralized key networking and build a key interoperability foundation that is resistant to packet sniffing and time-series brute-force attacks. S2, Business Encryption Sharding: The original medical fund flow data within the hospital is split into business-level segments, and mixed encryption sharding encapsulation processing is performed to generate reconciliation ciphertext shards that cannot be decrypted from the original information. S3, Hierarchical encrypted storage: The blockchain terminal distributes fragmented encrypted text based on node permissions, and completes cross-institutional encrypted text synchronous storage in a decentralized manner, realizing hierarchical permission isolation and retention of encrypted text; S4. Unobtrusive Ciphertext Computation: Calls a medical-specific adaptive homomorphic operator to perform collaborative computation of the difference between fund inflows and outflows in the ciphertext domain, without decrypting the plaintext transaction records throughout the entire process, thus protecting fund privacy. S5. Two-way security verification: Linked symmetric and asymmetric two-way encryption verification mechanism to verify the legality of homomorphic computation ciphertext, eliminate abnormally tampered ciphertext fragments, and block malicious fragments; S6. Risk Control Desensitization Correction: Compliant desensitization adapts to medical insurance reconciliation risk control rules, corrects encrypted calculation deviations, generates preliminary reconciliation encrypted results, and conforms to medical insurance compliance standards. S7. On-chain reconciliation and confirmation of rights: Blockchain consensus nodes cross-verify the preliminary review results, complete the closed-loop cross-institutional encrypted reconciliation and confirmation of rights archiving, and solidify the legal effect of the reconciliation. S8. End-to-end traceability closed loop: Retain the traceability fingerprint of the hierarchical key, authorize compliant terminals to provide evidence and verify the reconciliation link as needed, complete the end-to-end encrypted closed loop, and meet the audit and evidence requirements.

2. The cross-institutional medical fund encrypted reconciliation and collaborative calculation method based on homomorphic encryption according to claim 1, characterized in that: In step S1, the federated key blockchain ledger is divided into three layers: identity layer, fragmented key layer, and reconciliation result layer. Terminal certificates are issued using the 2048-bit fixed-bit RSA national cryptographic algorithm. The key rotation cycle is 7-9 calendar days, the retention time of discarded keys on the chain is 60-90 days, and the length of cross-institutional peer-to-peer private key signatures is 256-320 bits. In step S1, the central processing unit initially generates 500-1500 sets of key data. A single real reconciliation key is hidden within the key cluster and transmitted synchronously. The transmission is divided into three time-division pause phases. The first phase pause lasts for 0.5-1 seconds, during which 500-600 fake keys are added simultaneously. The second phase pause lasts for 0.3-0.8 seconds, during which 500-800 fake keys are added simultaneously. The third phase pause lasts for 0.6-0.9 seconds, during which 1500-1800 fake keys are added simultaneously. Only compliant nodes in the network are equipped with verification keys to extract the real keys.

3. The cross-institutional medical fund encrypted reconciliation and collaborative calculation method based on homomorphic encryption according to claim 2, characterized in that: In step S2, the medical fund flow is split into three categories using 128-bit block AES national cryptographic encryption, with the Paillier key bit range of 2048-4096 bits, the fund amount of a single segment ranging from 100 to 50,000 yuan, and the segment encoding is a fixed sequence of 6-9 bits. The compliance pass rate of segment encryption is 99.2%-99.7%.

4. The cross-institutional medical fund encrypted reconciliation and collaborative calculation method based on homomorphic encryption according to claim 3, characterized in that: In step S3, a lightweight PBFT consensus is adopted, which is compatible with a malicious node ratio of 15%-25%. The sharding hash uses a 256-bit fixed SHA algorithm, the abnormal sharding alarm latency ranges from 0.2s to 0.4s, and the encrypted text body stores a fixed 192-bit encryption key.

5. The cross-institutional medical fund encrypted reconciliation and collaborative calculation method based on homomorphic encryption according to claim 4, characterized in that: In step S4, the medical adaptation Paillier operator retains two decimal places for pricing. The operator sandbox process occupies 8%-15% of the computing power and is only adapted for fund addition and subtraction reconciliation operations. The number of external access ports blocked is between 12 and 18 to prevent illegal tampering and invocation.

6. The cross-institutional medical fund encrypted reconciliation and collaborative calculation method based on homomorphic encryption according to claim 5, characterized in that: In step S5, double encryption verification is performed, with the hash deviation of the legitimate ciphertext ranging from 0.000 to 0.009, the isolation and freezing period for malicious nodes ranging from 7 to 15 working days, the physical code of the tampered ledger binding terminal being verified, and the ledger storage block capacity ranging from 1.5MB to 2MB.

7. The cross-institutional medical fund encrypted reconciliation and collaborative calculation method based on homomorphic encryption according to claim 6, characterized in that: In step S6, the risk control range for compliant reconciliation discrepancies in medical insurance is 0-200 yuan, the number of times exceeding the limit is reviewed is 2-4 times, the time taken for a single review is 0.6s-1.0s, the archiving and storage time for risk control work orders is 3-5 years, and it is compatible with the medical insurance audit ledger standard.

8. The cross-institutional medical fund encrypted reconciliation and collaborative calculation method based on homomorphic encryption according to claim 7, characterized in that: In step S7, the number of valid signature nodes for reconciliation ranges from 3 to 7 heterogeneous institutions, the validity period of the signature is fixed at 15-24 hours, and the archiving and storage period of the reconciliation fragment key ranges from 7 to 10 years, which is in line with the national standard storage period for medical financial records.

9. The cross-institutional medical fund encrypted reconciliation and collaborative calculation method based on homomorphic encryption according to claim 8, characterized in that: In step S8, the timing accuracy of the traceability fingerprint is in the millisecond range of 1-10ms, the length of the two-factor combination of the decryption key of the monitoring terminal is in the range of 384-512 bits, and the validity period of the read-only encrypted permission of the business institution is 30-90 days, with the permission being automatically revoked upon expiration.

10. A cross-institutional medical fund encrypted reconciliation and collaborative calculation system based on homomorphic encryption, used to implement the method of claim 9, characterized in that: include: The Federal Key Blockchain Ledger Module is used for decentralized, hierarchical management of agency terminal keys and for completing identity verification. The hierarchical hybrid encryption sharding module is used to split medical fund flow records and complete triple hybrid encryption sharding; The decentralized encrypted text synchronization module is used for hierarchical control of cross-institutional encrypted text fragment synchronization and evidence storage. The medical adaptive homomorphic computation module is used for seamless calculation of compliant fund differences in the encrypted domain; A two-way encryption verification module is used for symmetric and asymmetric linkage verification of the legitimacy of encrypted fragments; The medical insurance compliance desensitization correction module is used to desensitize privacy and correct calculation errors in reconciliation encrypted text; The on-chain reconciliation consensus and rights confirmation module is used to verify and archive reconciliation results across institutional nodes. The key fingerprint traceability verification module is used to generate traceability fingerprints and manage terminal evidence presentation permissions in a hierarchical manner.

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