A method for tamper-proof verification of personal radiation dose logs from CT scans
By employing a dual encryption strategy combining asymmetric encryption and hash algorithms, along with a third-party distributed evidence storage node, the problem of tampering with CT scan dose logs was solved, enabling transparent dose data verification and efficient traceability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SUZHOU MUNICIPAL HOSPITAL
- Filing Date
- 2026-02-13
- Publication Date
- 2026-06-02
AI Technical Summary
Patients cannot obtain independently verified CT scan dose data vouchers, existing system logs are easily tampered with and investigations are inefficient, there is a lack of transparent and neutral third-party verification tools, and tampering and tracing are difficult.
A dual encryption strategy combining asymmetric encryption and hash algorithms is used to sign and hash the dose logs, generating a unique verification identifier. This identifier is then stored and verified through a third-party distributed evidence storage node. Combined with a multi-dimensional verification mechanism, tampering traceability is achieved.
It provides transparent and neutral dosage data verification tools, which improves verification efficiency, reduces medical disputes, and enables accurate traceability of dosage data.
Smart Images
Figure CN122133182A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of log security technology, specifically, it relates to a method for preventing tampering and verifying personal radiation dose logs from CT examinations. Background Technology
[0002] Patients typically lack access to independently verifiable dosage data documentation. Even when QR codes are provided for verification, they may become invalid due to technical malfunctions; when patients raise questions, they can only rely on unilateral investigations and responses from hospitals or regulatory authorities, lacking transparent and neutral third-party verification tools.
[0003] When tampering is suspected, investigations often require manual comparison of massive amounts of data, which is inefficient. Even if anomalies are found, tracing the source back to a specific time is extremely difficult due to the personnel and operational instructions involved. Existing system logs may be incomplete or themselves susceptible to tampering by authorized individuals.
[0004] In view of this, the present invention is proposed. Summary of the Invention
[0005] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by the present invention is as follows:
[0006] A method for tamper-proof verification of a personal radiation dose log from a CT scan includes, for example, the following steps:
[0007] Step 1: When the CT equipment performs an examination, it collects radiation dose data and related operation information in real time and generates a raw dose log;
[0008] Step 2: Encrypt the original dose log to generate an encrypted log string and a unique verification identifier;
[0009] Step 3: Synchronize the original dose log, the encrypted log string, and the verification identifier to a third-party evidence storage node for distributed storage;
[0010] Step 4: When receiving a verification request, obtain the log to be verified and the corresponding verification identifier, and retrieve the associated encrypted log string and the original dose log backup from the third-party evidence storage node;
[0011] Step 5: Encrypt the log to be verified using a preset verification algorithm, compare the result with the retrieved encrypted log string, and combine this with the consistency verification of the original dose log backup to output the verification result.
[0012] In a preferred embodiment of the present invention, the encryption process in step S2 includes: signing the original dose log using an asymmetric encryption algorithm, and calculating the hash value of the original dose log using a SHA-256 or SM3 hash algorithm. The encrypted log string includes a digital signature and a hash value, and the verification identifier is a unique string generated based on the patient's unique identifier, examination timestamp, and device number.
[0013] In a preferred embodiment of the present invention, the third-party evidence storage node in step S3 includes a consortium blockchain node cluster and a third-party trusted server. The consortium blockchain node cluster is jointly maintained by the hospital, regulatory agency and independent third-party institution. The original dose log, log encryption string and verification identifier are synchronized to at least 3 different consortium blockchain nodes and 1 third-party trusted server using a redundant storage method.
[0014] In a preferred embodiment of the present invention, the associated operation information in step S1 includes patient identification, CT equipment number, examination parameters, operator employee number, examination start timestamp, examination end timestamp, and equipment status data. The original dose log is stored in a structured data format and includes data field check bits.
[0015] As a preferred embodiment of the present invention, the triggering method of the verification request in step S4 includes: the patient actively initiates verification through the terminal device, the hospital system automatically initiates batch verification on a regular basis, and the regulatory agency initiates targeted verification according to regulatory needs. The log to be verified may come from the patient's handheld terminal, the hospital information system, or the regulatory platform.
[0016] In a preferred embodiment of the present invention, the preset verification algorithm in step S5 corresponds one-to-one with the encryption processing algorithm in step S2. When asymmetric encryption is used, the digital signature in the encrypted log string is decrypted using the public key to verify the validity of the signature. When a hash algorithm is used, the hash value of the log to be verified is calculated and compared with the retrieved hash value. At the same time, the consistency between the log to be verified and the data backup of the original dose log is verified by field-level comparison.
[0017] As a preferred embodiment of the present invention, it also includes a tracing step: when the verification result is log tampering, based on the timestamp sequence, operation link data and device status log stored by the third-party evidence storage node, the time node where the tampering occurred, the range of data modification and the associated operation account are located, and a tracing report is generated.
[0018] In a preferred embodiment of the present invention, step S2 further includes adding a timestamp to the encrypted log data. The timestamp is calibrated using a blockchain time synchronization mechanism to ensure that the log generation time is immutable. The verification identifier is uniquely associated with the patient's CT examination report and supports verification by scanning the report QR code or entering the verification identifier.
[0019] As a preferred embodiment of the present invention, step S5 also includes a multi-dimensional verification mechanism: in addition to encrypted string comparison and data consistency verification, the format legality, field integrity and logical rationality of log data are also verified, wherein the logical rationality verification includes the matching degree verification of radiation dose data with CT equipment parameters and examination duration.
[0020] As a preferred embodiment of the present invention, it also includes an anomaly warning step: when the verification results are tampered with for 3 consecutive times or a key field is found to be tampered with in a single verification, an early warning message is automatically sent to the regulatory agency and the quality control department of the corresponding hospital. The early warning message includes the verification identifier, details of the tampered field and preliminary traceability results, and the early warning record is synchronized to a third-party evidence storage node for archiving.
[0021] Compared with the prior art, the present invention has the following advantages:
[0022] This invention provides patients with a transparent and neutral tool for independently verifying dosage data by storing log data through a third-party distributed evidence storage node and combining double encryption processing with an independent verification process. This completely solves the problem of patients relying on one-sided responses from hospitals, increases patients' trust in dosage data, and reduces medical disputes. By replacing manual comparison with encrypted string comparison and multi-dimensional automated verification, the efficiency of tamper verification is greatly improved. At the same time, based on the timestamp sequence and operation link data of the third-party evidence storage, accurate traceability of tampered information is achieved, solving the shortcomings of low efficiency in tamper investigation and difficulty in tracing the source in existing technologies.
[0023] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description
[0024] In the attached diagram:
[0025] Figure 1 This is a flowchart of a method for tamper-proof verification of personal radiation dose logs from CT scans. Detailed Implementation
[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention.
[0027] Example 1: A method for tamper-proof verification of a personal radiation dose log for CT examinations, comprising the following steps:
[0028] Step S1: Acquisition of CT radiation dose data and related operational information.
[0029] Throughout the entire CT scan process, the built-in data acquisition module of the device works in conjunction with the Hospital Information System (HIS) and Picture Archiving and Communication System (PACS) to collect core radiation dose data and related operational information in real time, ensuring the integrity and authenticity of the data source. Specifically, the data acquisition module has a sampling frequency of no less than 10Hz to accurately capture the dynamic changes in radiation dose during the examination, while ensuring the real-time synchronization of related operational information.
[0030] After the data acquisition is completed, all data is transmitted to a dedicated encrypted server and stored in a preset structured data format. The data fields include radiation dose data, patient identification, CT equipment number, examination parameters, operator employee number, examination start timestamp, examination end timestamp, equipment status data, and field check bits. The field check bits are used to initially verify the integrity of the data transmission process and avoid data anomalies caused by transmission errors.
[0031] Step S2: Encryption of the original dose log and generation of verification identifier.
[0032] As the core carrier of radiation dose data, the security of raw dose logs directly determines the effectiveness of subsequent verification and traceability. Existing technologies using single encryption methods are easily cracked and lack a unique association with patient examination reports, leading to cumbersome or ineffective verification processes. This step employs a dual encryption strategy combining asymmetric encryption and hash operations to enhance the log data's tamper-proof capabilities. Simultaneously, it generates a unique verification identifier and binds it with a timestamp, achieving precise association between the log and examination report, providing a foundation for subsequent multi-entity verification.
[0033] The core logic of the dual encryption strategy lies in the following: Asymmetric encryption algorithms ensure the unforgeability of log signatures through a public-private key separation mechanism; SHA-256 or SM3 hash algorithms ensure the immutability of log data through fixed-length hash value mapping; the combination of these two forms a dual protection of signature and hash, meaning that data modification at any stage will lead to verification failure. Simultaneously, the timestamp is calibrated using a blockchain time synchronization mechanism to avoid traceability deviations caused by time tampering; the verification identifier is uniquely associated with the patient's examination report, simplifying the verification initiation process.
[0034] First, asymmetric encryption signature processing.
[0035] Asymmetric encryption algorithms use a public-key encryption and private-key decryption mechanism to achieve digital signatures on the original dose logs. The hospital or regulatory agency owning the CT equipment holds the private key, which is used to sign the original dose logs; the public key is made public and used for signature validity verification during subsequent verification processes.
[0036] Specific processing procedure:
[0037] The original dose log was structured and converted into a standard string format;
[0038] The string is encrypted using the private key to generate a digital signature;
[0039] Digital signatures are stored in conjunction with the original dose logs, serving as one of the core bases for subsequent verification.
[0040] The core advantage of asymmetric encryption lies in the uniqueness and confidentiality of the private key. Only the authorized entity holding the private key can generate a valid digital signature, which cannot be forged by any other entity. Even if the log data is tampered with, the tamperer cannot generate a corresponding valid digital signature, thus ensuring the authenticity of the log.
[0041] Second, perform hash value calculation.
[0042] The original dose logs are hashed using either the SHA-256 or SM3 hash algorithm to generate a fixed-length hash value (256 bits for SHA-256 and 256 bits for SM3).
[0043] The specific calculation formula is as follows: ;in This represents the original dose log string after structured processing; This represents the SHA-256 or SM3 hash function; This represents the hash value corresponding to the original dose log;
[0044] Hash algorithms exhibit an avalanche effect, meaning that even minor modifications to the original log data will significantly alter the hash value. Furthermore, hash values are of fixed length, making it impossible to deduce the original log data from the hash value, thus ensuring data privacy. Hash value comparison allows for a quick determination of whether the log to be verified matches the original log.
[0045] Finally, a verification identifier is generated and a timestamp is added: the verification identifier is generated based on the patient's unique identifier, the examination timestamp, and the equipment number to ensure that each CT examination log has a unique and identifiable identifier; at the same time, a timestamp is added to the encrypted log data, and a blockchain time synchronization mechanism is used for calibration to ensure that the time information is tamper-proof.
[0046] Step S3: Third-party distributed evidence storage.
[0047] Existing centralized storage models have single points of failure and tampering risks. This step uses a distributed evidence storage node composed of a consortium blockchain node cluster and a third-party trusted server, and adopts a redundant storage strategy to synchronously store the original dose log, log encryption string and verification identifier on multiple nodes to ensure the high availability and tamper-proof characteristics of the data.
[0048] The core logic of distributed evidence storage is as follows: the consortium blockchain node cluster is jointly maintained by the hospital, regulatory agencies and independent third-party institutions. Any tampering behavior of any node must obtain the consensus of most nodes, and the tampering record will be recorded synchronously by all nodes, making it difficult to hide. The third-party trusted server serves as an independent backup node, further reducing the risk of data loss. The redundant storage strategy ensures that even if some nodes fail, complete data can still be retrieved from other nodes.
[0049] Composition of third-party evidence storage nodes: Third-party evidence storage nodes include consortium blockchain node clusters and third-party trusted servers; Consortium blockchain node clusters: Deployed and maintained by at least 3 independent entities, each node has independent storage devices and computing power resources, and data synchronization and consensus are achieved between nodes through blockchain communication protocols; Third-party trusted servers: Servers provided by service providers with national information security level protection level 3 or above qualifications are selected, independent of the consortium blockchain node clusters, and used for off-site data backup.
[0050] The redundant storage strategy is as follows: the original dose log, the encrypted log string, and the verification identifier are synchronized to the third-party evidence storage node via an encrypted transmission protocol. The specific storage rules are as follows:
[0051] The data is synchronized to at least three different consortium blockchain nodes, each storing a complete dataset. Consensus algorithms are used between nodes to ensure data consistency. The data is also synchronized to a trusted third-party server for off-site backup storage, with the backup data synchronized in real time with the consortium blockchain node data. All evidence storage nodes use a combination of data sharding and encrypted storage to further enhance data security.
[0052] Step S4: Verify the receipt of the request and the retrieval of data.
[0053] To meet the verification needs of different entities, this step is designed with multiple verification triggering methods to support patients, hospitals, and regulatory agencies to initiate verification from different channels. At the same time, the target data of the third-party evidence storage node is associated with the verification identifier to ensure the accuracy and completeness of the retrieved data and provide data support for subsequent verification.
[0054] The verification identifier serves as a unique association key, enabling accurate matching between the log to be verified and third-party evidence storage data; multiple triggering methods cover both active and passive verification scenarios, meeting diverse needs such as patient rights protection, hospital quality control, and regulatory verification; and encrypted transmission is used during data retrieval to prevent data leakage.
[0055] Verification request triggering method.
[0056] There are three types of ways to trigger a verification request:
[0057] Patient-initiated verification: Patients can initiate a single verification request by scanning the QR code on the CT scan report or entering a verification identifier through mobile APP, WeChat mini-program or other terminal devices.
[0058] The hospital system automatically initiates batch verifications on a regular basis: The hospital's quality control department sets the verification cycle, and the system automatically extracts the verification identifiers of all CT examination logs for the day and initiates batch verifications for internal quality control.
[0059] Targeted verification initiated by regulatory agencies: Regulatory agencies initiate targeted verifications based on regulatory needs (such as receiving patient complaints or conducting special inspections) by inputting specific verification identifiers or filtering logs from specific time periods and devices through the regulatory platform.
[0060] The sources and data retrieval of logs to be verified can be from three channels: patient handheld terminals, logs stored in the hospital information system for HIS / PACS, and log copies retained by the regulatory platform for regulatory agencies.
[0061] The data retrieval process is as follows:
[0062] Upon receiving a verification request, extract the verification identifier from the request; based on the verification identifier, send a data retrieval request to the third-party evidence storage node;
[0063] After verifying the legitimacy of the request, the evidence storage node returns the associated encrypted log string and a backup of the original dose log.
[0064] If some consortium blockchain nodes fail, the system will automatically switch to other normal nodes or a trusted third-party server to retrieve data.
[0065] Step S5: Multi-dimensional verification and result output.
[0066] Existing verification methods are limited in scope and vulnerable to legitimate tampering. This step employs a combined mechanism of encrypted string comparison, data consistency verification, and multi-dimensional auxiliary verification to ensure the accuracy and comprehensiveness of the verification results. The preset verification algorithm corresponds one-to-one with the encryption algorithm in step S2, achieving precise verification; multi-dimensional auxiliary verification covers format, field, and logic levels, further eliminating the risk of tampering.
[0067] Encryption string comparison verifies the integrity and authenticity of log data, data consistency verification ensures that the log to be verified is completely matched with the original backup, and multi-dimensional auxiliary verification makes up for the shortcomings of single encryption verification. The combination of the three forms a closed-loop verification system, which effectively identifies various tampering behaviors.
[0068] The encrypted string comparison and signature verification process is as follows:
[0069] Based on the encryption method in step S2, the corresponding preset verification algorithm is used for calculation:
[0070] If asymmetric encryption is used: decrypt the digital signature in the encrypted log string using the public key to verify the validity of the signature; if the signature is invalid, it is directly determined that the log has been tampered with.
[0071] If a hash algorithm is used: calculate the hash value of the log to be verified and compare it with the hash value retrieved from the evidence storage node; if The log was determined to have been tampered with.
[0072] The data consistency verification steps are as follows: Verify each data field of the log to be verified against the backup of the original dose log using a field-level comparison method.
[0073] The comparison fields include all core fields such as radiation dose data, patient identification, equipment number, examination parameters, and timestamps. If any field mismatch occurs and the encrypted string comparison fails, the log is considered tampered with. Field check bits assist in verification; if check bits mismatch, transmission errors are investigated first, and the data is retrieved again for verification. Multi-dimensional auxiliary verification includes, in addition to core verification, format validity, field completeness, and logical rationality checks. Format validity check: verifies whether the structured format of the log to be verified conforms to preset standards and whether the field data types are correct, preventing the circumvention of encryption verification by modifying the format. Field completeness check: checks whether the log to be verified is missing core fields, preventing tampering by deleting fields. Logical rationality check: verifies the matching degree between radiation dose data and CT equipment parameters and examination duration, judging the data's rationality based on industry standard thresholds; if it exceeds the reasonable range and there is no reasonable explanation, the log is considered abnormal.
[0074] Based on the above verification results, three types of verification conclusions are output:
[0075] Verification passed: encrypted strings match, data fields are fully matched, and multi-dimensional auxiliary verification shows no anomalies;
[0076] Log tampering: Inconsistent encrypted strings, mismatched data fields, or clear traces of tampering discovered through multi-dimensional auxiliary verification;
[0077] Verification error: Verification cannot be completed due to non-tampering factors such as data transmission failure or missing data at the evidence storage node, and verification needs to be re-initiated.
[0078] Step S6: Tampering Tracing: When the verification result indicates log tampering, the tampered information needs to be accurately located to provide a basis for dispute resolution and liability determination. This step constructs a complete tracing chain based on the timestamp sequence, operation link data, and device status logs stored by third-party evidence storage nodes, enabling the traceability of tampering behavior.
[0079] The core logic is as follows: the consortium blockchain node cluster records the operation logs and timestamps of the entire process of log generation, transmission, and storage, and these logs cannot be tampered with; the operation link data includes the account information and operation instructions for each data access and modification; the device status log records the operating status and operation records of the CT device. The combination of these three can accurately reconstruct the tampering process.
[0080] The traceability process is as follows:
[0081] Extract the timestamp sequence of the target log stored by the third-party evidence storage node to locate the log data's generation time, first storage time, and access time;
[0082] Retrieve operation chain data and filter all operation records related to this log, including operation account, operation time, and operation type;
[0083] By combining the CT equipment status log, the consistency between the operation time and the equipment operating status was verified;
[0084] Based on the above data, the time point of the tampering, the scope of data modification (such as the specific fields that were tampered with), and the associated operation accounts are located, and a traceability report containing an operation chain diagram, timeline, and tampering details is generated.
[0085] Step S7: The specific methods for abnormal warnings are as follows:
[0086] To respond promptly to log tampering and prevent risks from escalating, this step sets up abnormal early warning trigger conditions. When the conditions are met, early warning information is automatically sent to relevant entities, and the early warning record is archived to ensure a closed-loop supervision.
[0087] By setting quantitative warning thresholds, the system can accurately trigger warnings; warning information is synchronized with regulatory agencies and hospital quality control departments to ensure rapid response from responsible parties; and warning records are archived to third-party evidence storage nodes to provide evidence for subsequent investigations.
[0088] The warning triggering conditions and procedures are as follows:
[0089] Triggering conditions: Three consecutive verification results show tampering, or a single verification reveals tampering of a key field;
[0090] Warning information generation: The warning information includes verification identifier, details of tampered fields, and preliminary results of source tracing;
[0091] Warning sending: Automatically send warning information to designated contacts of regulatory agencies and quality control departments of corresponding hospitals via SMS, system messages, etc.
[0092] Record archiving: Synchronize early warning records to third-party evidence storage nodes for archiving to ensure traceability.
[0093] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for tamper-proof verification of a personal radiation dose log from a CT scan, characterized in that: Including, for example, the following steps: Step 1: When the CT equipment performs an examination, it collects radiation dose data and related operation information in real time and generates a raw dose log; Step 2: Encrypt the original dose log to generate an encrypted log string and a unique verification identifier; Step 3: Synchronize the original dose log, the encrypted log string, and the verification identifier to a third-party evidence storage node for distributed storage; Step 4: When receiving a verification request, obtain the log to be verified and the corresponding verification identifier, and retrieve the associated encrypted log string and the original dose log backup from the third-party evidence storage node; Step 5: Encrypt the log to be verified using a preset verification algorithm, compare the result with the retrieved encrypted log string, and combine this with the consistency verification of the original dose log backup to output the verification result.
2. The method for tamper-proof verification of a personal radiation dose log for CT examinations according to claim 1, characterized in that, The encryption process in step S2 includes: signing the original dose log using an asymmetric encryption algorithm, and calculating the hash value of the original dose log using the SHA-256 or SM3 hash algorithm. The encrypted log string includes a digital signature and a hash value. The verification identifier is a unique string generated based on the patient's unique identifier, examination timestamp, and device number.
3. The method for tamper-proof verification of a personal radiation dose log for CT examinations according to claim 1, characterized in that, The third-party evidence storage nodes mentioned in step S3 include a consortium blockchain node cluster and a third-party trusted server. The consortium blockchain node cluster is jointly maintained by the hospital, regulatory agencies and independent third-party institutions. The original dose log, log encryption string and verification identifier are synchronized to at least 3 different consortium blockchain nodes and 1 third-party trusted server using a redundant storage method.
4. The method for tamper-proof verification of a personal radiation dose log for CT examinations according to claim 1, characterized in that, The associated operation information in step S1 includes patient identification, CT equipment number, examination parameters, operator employee number, examination start timestamp, examination end timestamp, and equipment status data. The original dose log is stored in a structured data format and includes data field check bits.
5. The method for tamper-proof verification of a personal radiation dose log for CT examinations according to claim 1, characterized in that, The verification request in step S4 can be triggered in the following ways: the patient initiates verification actively through the terminal device, the hospital system initiates batch verification automatically on a regular basis, or the regulatory agency initiates targeted verification according to regulatory needs. The verification log can come from the patient's handheld terminal, the hospital information system, or the regulatory platform.
6. The method for tamper-proof verification of a personal radiation dose log for CT examinations according to claim 1, characterized in that, The preset verification algorithm described in step S5 corresponds one-to-one with the encryption processing algorithm in step S2. When asymmetric encryption is used, the digital signature in the encrypted log string is decrypted using the public key to verify the validity of the signature. When a hash algorithm is used, the hash value of the log to be verified is calculated and compared with the retrieved hash value. At the same time, the consistency between the log to be verified and the data backup of the original dose log is verified by field-level comparison.
7. The method for tamper-proof verification of a personal radiation dose log for CT examinations according to claim 1, characterized in that, It also includes a tracing step: when the verification result indicates log tampering, based on the timestamp sequence, operation link data and device status logs stored by the third-party evidence storage node, the time node where the tampering occurred, the scope of data modification and the associated operation account are located, and a tracing report is generated.
8. The method for tamper-proof verification of a personal radiation dose log for CT examinations according to claim 1, characterized in that, Step S2 also includes adding a timestamp to the encrypted log data. The timestamp is calibrated using a blockchain time synchronization mechanism to ensure that the log generation time is immutable. The verification identifier is uniquely associated with the patient's CT examination report and supports verification by scanning the report's QR code or entering the verification identifier.
9. The method for tamper-proof verification of a personal radiation dose log for CT examinations according to claim 1, characterized in that, Step S5 also includes a multi-dimensional verification mechanism: in addition to encrypted string comparison and data consistency verification, the format legality, field integrity and logical rationality of log data are also verified. The logical rationality verification includes the matching degree verification of radiation dose data with CT equipment parameters and examination duration.
10. A method for tamper-proof verification of a personal radiation dose log for CT examinations according to claim 1, characterized in that, It also includes an anomaly warning step: when three consecutive verification results show tampering or a single verification finds that a key field has been tampered with, an warning message is automatically sent to the regulatory agency and the quality control department of the corresponding hospital. The warning message includes the verification identifier, details of the tampered field, and preliminary results of the tracing. At the same time, the warning record is synchronized to a third-party evidence storage node for archiving.