Aiming at the problems of lack of Industrial Control System (ICS) data and poor detection of unknown attacks by industrial control intrusion detection systems, an unknown attack intrusion detection method for industrial control systems based on Generative Adversarial Transfer Learning network (GATL) was proposed. Firstly, causal inference and cross-domain feature mapping relations were introduced to reconstruct the data to improve its understandability and reliability. Secondly, due to the data imbalance between source domain and target domain, domain confusion-based conditional Generative Adversarial Network (GAN) was used to increase the size and diversity of the target domain dataset. Finally, the differences and commonalities of the data were fused through domain adversarial transfer learning to improve the detection and generalization capabilities of the industrial control intrusion detection model for unknown attacks in the target domain. The experimental results show that on the standard dataset of industrial control network, GATL has an average F1-score of 81.59% in detecting unknown attacks in the target domain while maintaining a high detection rate of known attacks, which is 63.21 and 64.04 percentage points higher than the average F1-score of Dynamic Adversarial Adaptation Network (DAAN) and Information-enhanced Adversarial Domain Adaptation (IADA) method, respectively.
Private Set Intersection (PSI) is an important solution for privacy information sharing. A fair multi-party PSI protocol based on cloud server was proposed for the unfairness caused by the existing protocols in which the parties involved do not have simultaneous access to the calculation results. Firstly, the storage of a sub-share of the private information in Garbled Bloom Filter (GBF) was accomplished by using hash mapping. Secondly, in order to avoid the leakage of the index value of each party’s set element during the interaction, combined with Oblivious Transfer (OT) technique, the share replacement of the stored information was realized. Finally, the bit-by-bit calculation was performed by the cloud server, and the results were returned to each party at the same time to ensure the fairness of each party’s access to the results. The correctness and security analysis of the protocol shows that the proposed protocol can achieve the fairness of the parties in obtaining the intersection results, and can resist the collusion of parties with the cloud server. The performance analysis shows that both of the computational complexity and the communication complexity of the proposed protocol are independent of the total number of elements contained in the set of participants. Under the same conditions, compared with Multi-party PSI protocol (MPSI), practical multiparty maliciously-secure PSI protocol (PSImple) and Private Intersection Sum algorithm (PI-Sum), the proposed protocol has less storage overhead, communication overhead and running time.
In automated industrial scenarios, the amount of time series log data generated by a large number of industrial devices has exploded, and the demand for access to time series data in business scenarios has further increased. Although HBase, a distributed column family database, can store industrial time series big data, the existing strategies cannot meet the specific access requirements of industrial time series data well because the correlation between data and access behavior characteristics in specific business scenarios is not considered. In view of the above problem, based on the distributed storage system HBase, and using the correlation between data and access behavior characteristics in industrial scenarios, a distributed storage performance optimization strategy for massive industrial time series data was proposed. Aiming at the load tilt problem caused by characteristics of industrial time series data, a load balancing optimization strategy based on hot and cold data partition and access behavior classification was proposed. The data were classified into cold and hot ones by using a Logistic Regression (LR) model, and the hot data were distributed and stored in different nodes. In addition, in order to further reduce the cross-node communication overhead in storage cluster and improve the query efficiency of the high-dimensional index of industrial time series data, a strategy of putting the index and main data into a same Region was proposed. By designing the index RowKey field and splicing rules, the index was stored with its corresponding main data in the same Region. Experimental results on real industrial time series data show that the data load distribution tilt degree is reduced by 28.5% and the query efficiency is improved by 27.7% after introducing the optimization strategy, demonstrating the proposed strategy can mine access patterns for specific time series data effectively, distribute load reasonably, reduce data access overhead, and meet access requirements for specific time series big data.
Aiming at the problem that the existing adversarial example generation methods require a lot of queries to the target model, which leads to poor attack effects, a Text Adversarial Examples Generation Method based on BERT (Bidirectional Encoder Representations from Transformers) model (TAEGM) was proposed. Firstly, the attention mechanism was adopted to locate the keywords that significantly influence the classification results without query of the target model. Secondly, word-level perturbation of keywords was performed by BERT model to generate candidate adversarial examples. Finally, the candidate examples were clustered, and the adversarial examples were selected from the clusters that have more influence on the classification results. Experimental results on Yelp Reviews, AG News, and IMDB Review datasets show that compared to the suboptimal adversarial example generation method CLARE (ContextuaLized AdversaRial Example generation model) on Success Rate (SR), TAEGM can reduce the Query Counts (QC) to the target model by 62.3% and time consumption by 68.6% averagely while ensuring the SR of adversarial attacks. Based on the above, further experimental results verify that the adversarial examples generated by TAEGM not only have good transferability, but also improve the robustness of the model through adversarial training.
In order to improve the transformation efficiency of tile-pyramid image, a 15-parameter projection transformation method was established by quartic polynomial based on the view model of digital earth. The influencing factors for selecting the size of tile image were discussed theoretically, and an optimization method to determine the size and depth of tile-pyramid was given. To test this algorithm, a basic digital earth environment BDE2 was constructed by adopting JOGL. The analysis and experimental results show that tile-pyramid in 10m pixel accuracy constructed by this algorithm only has 10 layers and less than 5×10-5 average error; meanwhile, the proposed algrithm has low complexity, close stitching, high definition and low distortion, and can effectively avoid stitch cracks and characteristics distortion after the image is transformed.
Loop program has a significant amount of execution time in digital signal processing software, temporary storage of loop code with instruction buffer can reduce the number of program memory access to improve the performance of processor. A loop instruction buffer was added in the instruction pipeline. It could store and dispatch instructions of loop program in the software pipelining manner. The instructions of loop program needed to be accessed from program memory only once but executed many times, so the number of memory access was reduced. During the loop instructions were dispatched from buffer, the program memory could be signaled to sleep to reduce the power consumption of processor. In the typical application program, the instruction pipeline can be idle above 90%, and the performance of processor is improved about 10%, the overhead of loop buffer is 9% of the instruction pipeline.
A low power branch encoding method was presented for decreasing the SoC bus power dissipation. This method's basic principle is: for the address bus, when the address bus is sequential, the address bus is frozen, and when the address bus is non-sequential, the window size is adjusted dynamically to apply the Bus-Invert (BI) method on the address bus. For the data bus, two threshold values are figured out for different data size respectively. If the Hamming distance locates between these two threshold values, the valid-data-channel switching dense area is found and inverted, otherwise applies the BI encoding. This method's encoding and decoding circuits are realized in the Advanced High Performance Bus (AHB) system. The experimental result demonstrates that compared with uncoded situation, this method decreases the address/data bus toggle rate by 51.2%/22.4%, and the system power is reduced by 28.9%. Compared with T0,BI and other encoding methods realized in the same system, the branch encoding is more superior in the toggle rate and power dissipation.