To address the issues of insufficient privacy protection, lack of confidentiality, and absence of traceability mechanisms in resource-constrained application scenarios such as IoT nodes or mobile network group communications, this paper proposes a traceable ring signcryption privacy protection scheme based on the SM9 algorithm. In detail, the ring signcryption structure is designed based on the SM9 identity-based cryptography algorithm framework. Additionally, the scheme introduces a dynamic accumulator to compress ciphertext length and optimizes the algorithm to improve computational efficiency. Under the random oracle model, it is proved that the scheme has unforgeability, confidentiality, and conditional anonymity, and it is also demonstrated that conditional anonymity can be used to trace the identity of the actual signcryptor in the event of a dispute. Performance analysis shows that, compared with related schemes, this scheme improves the efficiency of signcryption, and the size of the signcryption ciphertext remains at a constant level.

The measurement of Earth’s free oscillations plays an important role in studying Earth’s large-scale structure. Space technology development presents a potential method to observe these normal modes by measuring intersatellite distances. However, the disturbance from Earth’s low-degree gravity field makes it challenging for low Earth orbit gravity measurement satellites such as Gravity Recovery and Climate Experiment and TianQin-2 to extract signals from Earth’s free oscillations directly. Here, we propose that by taking advantage of the high Earth orbit, the TianQin satellites can effectively avoid this disturbance, enabling direct measurement of Earth’s free oscillations. We derive an analytical waveform to describe the response of Earth’s free oscillations in TianQin. Based on this waveform, we use Bayesian analysis to extract the normal modes from numerical simulation data and perform parameter estimation. Our findings reveal that for a magnitude 7.9, Wenchuan-like earthquake, the resulting free oscillations will generate a signal with a signal-to-noise ratio of 73 in TianQin, and approximately 9 different modes can be distinguished. This result shows that TianQin can open a new window to examine Earth’s free oscillations and study Earth’s interior and earthquakes independently from ground-based gravity measurement.

Electronic voting plays a key role in the functioning of modern democracies. However, existing electronic voting protocols have some disadvantages, such as inability to trace the identity of malicious voters, insecurity of the voting process, and lack of a score voting paradigm. To address these issues, we propose a novel blockchain-based publicly traceable self-tallying voting protocol that implements scored voting. The protocol enables voters to score each candidate within a specified range. At the end of voting, the candidate with the highest total score is declared the winner of the election. Meanwhile, we take advantage of traceable ring signatures and homomorphic time-lock puzzles to balance the anonymity and accountability, and guarantee time-bounded privacy of the ballots. We prove that the proposed protocol satisfies the properties of full-anonymity, linkability, public traceability and time-bounded privacy. In addition, performance analysis shows that our protocol guarantees various properties of score voting with reasonable overhead.

In order to solve the problems of simple chaotic behavior, poor initial value sensitivity corresponding to the traditional one-dimensional chaotic maps, a one-dimensional combined chaotic map based on fuzzy entropy theory is proposed. The designed combinatorial chaotic map combines the definition of fuzzy entropy and the classical one-dimensional chaotic map, and can effectively improve the performance of the combinatorial chaotic maps by extending the system parameters. Through the experimental simulation and analysis of the bifurcation diagram, Lyapunov exponent, initial value sensitivity and other related properties of the combined chaotic map, the experimental results show that the combined chaotic map constructed in this paper has good chaotic properties such as initial value sensitivity and randomness.

In order to improve the problems of traditional one-dimensional chaotic mapping, such as small chaotic interval, discontinuous chaotic interval, simple chaotic behavior and low initial value sensitivity, a two-dimensional chaotic system based on 1D-LSE (Logistic self-embedding) chaotic mapping is proposed and further extended to a three-dimensional. Taking the improved two-dimensional chaotic system as an example, various performance indicators, such as the Lyapunov exponent, bifurcation diagram, sensitivity to initial values, bit change rate, and sequence randomness, are analyzed. The experimental simulation results show that the proposed two-dimensional chaotic system has a continuous chaotic interval, a larger chaotic interval, better performance in generating random sequences, higher sensitivity to initial values, and more complex chaotic characteristics.

To mitigate the security vulnerabilities associated with low security, small key space, and poor randomness in one-dimensional chaotic maps, we propose a universal model of n-dimensional combined chaotic maps. The proposed model constructs an n-dimensional combined chaotic map through the nesting and combination of one-dimensional chaotic maps. Using the two-dimensional chaotic map as a case study, we analyze the phase diagram, Lyapunov exponent, bifurcation diagram, initial value sensitivity, and correlation of the two-dimensional combined chaotic map through experimental simulations. Our simulation results demonstrate that the proposed model exhibits excellent randomness and unpredictability, which can enhance the security of communication systems.

Sine chaotic map is another type of chaotic map, but the map has problems such as small parameter range and uneven sequence distribution. In view of this, this paper proposes a multi-piecewise Sine chaotic map (MPSC) based on the idea of multi-piecewise representation of chaotic map. MPSC uses modular arithmetic, and can make the generated chaotic sequence more uniform by increasing in the number of Piecewise interval and control parameters. The experimental results show that MPSC not only has a larger parameter range, better randomness and initial-value sensitivity, but also increases the range of chaos interval with the increase of the number of segments and control parameters, and the chaos performance is further improved.

In order to solve the problem of limited key space and simple chaotic behavior of a single chaotic system, a high dimensional combined chaotic system model based on cosine transform is proposed. By combining one dimensional chaotic systems with weights, the output results are coupled by cosine transform, and then the corresponding high dimensional combined chaotic system is obtained. A color image encryption algorithm based on high-dimensional combined chaotic system and DNA encoding is designed according to the proposed high-dimensional combined chaotic system. The algorithm first uses the sequence value generated by the high-dimensional combined chaotic system to scramble the plaintext image at the bit and pixel levels. Secondly, DNA encoding technology is used to perform dynamic DNA operation on the scrambled image. Finally, the nonlinear component S-box is used to replace pixel values, which further improves the security of the algorithm. The simulation results show that the combined chaotic system has larger key space and better chaotic behavior, and the color image encryption algorithm based on high dimensional combined chaotic system and DNA can resist various common attack methods and has better security.

对混沌系统施以扰动可以有效解决由于计算机有限精度效应导致的混沌系统动力学特性退化问题.基于区间映射中Cantor集的构造方法,提出一种数字混沌系统参数扰动方案,该方案将混沌系统每次迭代后得到的序列值等比例地扩散到压缩后的混沌状态参数取值区间上,从而达到扰动混沌序列的目的.实验仿真及分析表明,增加扰动后的混沌系统具有更好的混沌特性、更大的参数范围和更高的复杂度.

Aiming at the problems of image encryption, such as poor encryption effect and poor security, a compound chaotic map ILSC is designed with Logistic map and Sine map as seed maps. Based on this, an image encryption algorithm based on compound chaotic system and dynamic DNA coding is proposed. First, according to the DNA random coding rules, the plaintext image is converted into a DNA matrix, and the scrambling operation is performed on it, and then the rows and columns of the DNA matrix are XORed to obtain the ciphertext image. Theoretical analysis and simulation results show that the proposed algorithm has a larger key space, the ciphertext image has higher information entropy, and can effectively resist statistical attacks, brute force attacks and other attack methods, and has better performance.

Aiming at the problems of image encryption algorithm in terms of security and encryption effect, an image encryption algorithm based on multiple chaotic maps and DNA encoding is proposed. First, using Logistic map to randomly scramble the rows and columns of the plaintext image, and convert the result into a binary matrix; second, according to the DNA coding rules, convert the binary matrix into a DNA matrix, and use 2D-LSMM map and Logistic-Sine system to perform in DNA encoding operation, XOR operation is performed on the obtained encoding matrix to obtain an encrypted DNA matrix; finally, according to the DNA decoding rules, the encrypted DNA matrix is converted into a digital image to obtain a ciphertext image. Experimental simulation and performance analysis show that the algorithm has better encryption and decryption effects, larger key space, and higher security and robustness.

Aiming at the problems of small parameter interval, simple chaotic behavior and poor initial value sensitivity of traditional one-dimensional chaotic map, a one-dimensional fractional chaotic system is improved by using the combination of Sine and Cosine map. On this basis, a Sine Cosine two-dimensional chaotic map is further proposed. Through the experimental simulation of the Lyapunov exponent, bifurcation diagram, initial value sensitivity and correlation of the chaotic system, the results show that the proposed two-dimensional chaotic map has larger chaotic parameter interval, better chaotic behavior and initial value sensitivity.

The cloud-assisted intelligent systems have attracted extensive attention due to their powerful data analysis and computation capabilities. However, how to handle encrypted data remains a challenging problem in intelligent systems. A promising solution is searchable symmetric encryption (SSE), which enables a client to privately outsource their data to the cloud while preserving keyword search functionality. In practice, dynamic SSE is more practical and supports efficient data addition and deletion. Unfortunately, data update will leak some additional information which can be exploited to break data privacy. To address this issue, forward and backward secure SSE schemes are proposed to reduce the leakage of data update. That is, forward security guarantees that the newly updated documents cannot reveal the previously searched keywords, while backward security guarantees that the server cannot recover the deleted documents. However, the existing forward and backward secure SSE schemes mainly consider curious-but-honest server. How to verify the soundness and completeness of search results is still a challenge. In this paper, we propose a noninteractive verifiable dynamic SSE scheme with forward and backward security from two universal accumulators. Specifically, the server in our scheme only needs one roundtrip to return the nondeleted search results to the client, which saves the communication overhead dramatically. Besides, our scheme can achieve public verification that anyone can verify the search results but not only the client who has the private key. Finally, we give a formal security analysis and compare the proposed scheme with other related work, the results show that our scheme can achieve the desired security properties with practical efficiency.

针对现有一维复合混沌系统存在的混沌区间不连续、混沌区间小、序列随机性差以及初值敏感性低等问题,提出一种改进的一维复合混沌系统.该系统使用Logistic映射和Sine映射作为种子映射,通过扩展系统参数对种子映射进行随机地复合和组合,然后取模得到混沌映射.对该复合混沌系统的李雅普诺夫(Lyapunov)指数、分岔图、序列随机性、相关系数、平衡度、初值敏感性和位变化率等性能指标进行仿真,结果表明,与相关的一维复合混沌系统相比,提出混沌系统混沌区间连续无断点、混沌区间较大、生成序列随机性能较好,初值敏感性较高,表现出更为复杂的混沌特性.

A color image encryption algorithm based on DNA coding and bit-level scrambling is proposed to solve the problems of poor effect and low security in the current color image encryption schemes.Firstly, the color image is preprocessed based on bite-level scrambling rules. Then the statistical information of the RGB plane itself was changed by means of DNA coding and cyclic shift. Finally, S-box is used for nonlinear replacement of pixel values after DNA decoding.Theoretical analysis and simulation results show that the algorithm can provide a larger key space, the cipher image also has higher information entropy, and has good security.

Secure deduplication is a promising solution to greatly reduce the storage space of the cloud. However, the encryption key is deterministically derived from the plaintext, such that who owns the plaintext has the derived key to decrypt the ciphertext. Therefore, how to revoke a user in deduplication schemes is a critical challenge. In the existing work, when updating the data authority, the data owner has to download the data from the cloud, decrypt, re-encrypt and finally upload them to the cloud. This process increases the communication and computation overheads. In this paper, we first propose a multi-user updatable encryption scheme. Specifically, the data owner can update the remote ciphertext under a new group key by sending an update token to the cloud. Then we adopt this technique to propose a new secure deduplication scheme supporting efficiently revoking an unauthorized user. In our scheme, the data owner just needs to send a token to the cloud to update the data authority, which saves the communication and computation costs. The security and efficiency analysis demonstrate that our proposed deduplication scheme can achieve the desired security properties with high efficiency.

为改善一维混沌系统密钥空间小,混沌行为简单等问题,提出一种n维组合混沌系统.在Logistic、Sine、Tent一维混沌系统中任选两个进行加权组合,将输出结果采用余弦变换进行耦合处理,进而得到相应的n维组合混沌系统.以二维混沌系统为例,对该混沌系统的Lyapunov指数以及分岔图等相关性等性能进行分析,并将其应于与较为经典的图像加密算法中.实验仿真结果表明,该组合混沌系统具有更大的密钥空间、更好的混沌行为,用于图像加密算法中具有较好的安全性能.

针对基于混沌系统生成的S盒存在非线性度较低等问题,文章针对基于切延迟椭圆反射腔映射系统(TD-ERCS)生成S盒的方法,首先证明了生成的S盒具有双射性,在此基础上,设计了一种改进的爬山算法,通过动态缩小布尔函数Walsh-Hadamard变换(WHT)的选取范围,将满足条件的6个布尔值进行取反运算,有效提升了双射S盒非线性度.理论和实验仿真分析表明,采用优化算法生成的S盒性能得到了有效提升,在算法效率、非线性度、严格雪崩准则和差分逼近概率等方面具备更好的性能.

针对传统图像增强算法对含噪手指静脉图像增强效果差、易丢失图像细节信息的问题,提出一种基于改进阈值函数的手指静脉图像增强算法.首先,对手指静脉图像进行二维小波变换,将小波变换后的低频子带系数非线性增强,各高频子带系数脊波变换得到脊波系数.然后,在脊波域利用改进阈值函数对脊波系数进行处理,将改进后的脊波系数通过脊波逆变换到小波域.最后,在小波域进行小波图像重构,得到增强后的手指静脉图像.实验结果表明,该算法在频域上能够有效降低噪声,减少失真并保留了较高的信息量,有较好的图像增强效果.

混沌保密技术是信息安全领域的一个研究热点,介绍了近年来在混沌伪随机序列生成技术和混沌图像加密技术,复合混沌序列生成技术研究方向取得的研究进展,分析并讨论相关研究存在的问题以及发展趋势.