A global progressive image secret sharing scheme under multi-group joint management.

Diverging from traditional secret sharing schemes, group secret sharing schemes enable the recovery of secret information through collaborative efforts among groups. Existing schemes seldom consider the issue of the secrecy level of image information between different groups. Therefore, we propose a global progressive image secret sharing scheme under multi-group joint management. For inter-group relations, multiple groups with different priority levels are constructed using the approach of bit-polar decomposition. In this arrangement, higher-level groups obtain clearer secret image information. For intra-group relations, a participant-weighted secret sharing scheme is constructed based on Chinese Remainder Theorem and Birkhoff interpolation, in which the participants' secret sub-shares are reusable. During the recovery process, the sub-images can be recovered within the intragroup with the corresponding level. Groups collaborate through lightweight overlay operations to obtain different layers of secret images, achieving a global progressive effect. Analysis results show that the scheme is both secure and practical for group secret sharing.

Integrating photothermal and plasmonic catalysis induced by near-infrared light for efficient reduction of 4-nitrophenol.

The reduction of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) is an important reaction in both chemical manufacturing and environmental protection. The design of a highly active, multifunctional and reusable catalyst for efficient 4-NP decontamination/valorization is therefore crucial to bring in economic and societal benefits. Herein, we achieve an efficient plasmonic-photothermal catalyst of Pd nanoparticles by growing them on graphene-polyelectrolytes self-assembly nanolayers via an in situ green reduction approach using polyelectrolyte as the reductant. The as-fabricated catalyst shows high catalytic behaviors and good stability (maintained over 92.5 % conversion efficiency after ten successive cycles) for 4-NP reduction under ultra-low catalyst dose. The rate constant and turnover frequency were calculated at 0.197 min-1 and 7.79 mmol g-1 min-1, respectively, which were much higher than those of most reported catalysts. Moreover, the as-prepared catalyst exhibited excellent photothermal conversion efficiency of ∼77 % and boosted 4-NP reduction by ∼2-fold under near-infrared irradiation (NIR). This study provides valuable insights into the design of greener catalytic materials and facilitates the development of multifunctional plasmonic-photothermal catalysts for diverse environmental, chemical, and energy applications using NIR.

Two-level QR code scheme based on region matrix image secret sharing algorithm.

Quick response (QR) codes have become increasingly popular as a medium for quickly and easily accessing information through mobile devices. However, the open-source nature of QR code encoding poses a risk of information leakage and potential attacks, especially with the growing use of QR codes in financial services and authentication applications. To mitigate the risk of information leakage due to open-source QR code encoding, this paper proposes a two-level QR code scheme based on a region matrix image secret sharing algorithm. In this scheme, the first-level public information can be directly obtained by scanning with any standard QR code scanner, while the two-level secret information can only be accessed by overlaying the shared images. To enhance the robustness of joint secret information recovery using shared images, this article designs a progressive image secret sharing algorithm based on region matrices. This algorithm meticulously processes high-priority share regions and generates multiple substitute shares. In the event of attacks on key shares, substitute shares can be employed to recover the secret information. For an increased payload capacity of each QR code, an adaptive pixel depth adjustment algorithm is devised. This algorithm ensures that the recovery of two-level secret information maintains high clarity, while not affecting the scanning functionality of each shared QR code. Experimental results validate the feasibility of this scheme, which simplifies the construction matrix, reduces matrix redundancy, and exhibits priority partitioning and higher robustness. Furthermore, QR codes embedding secret shares can safeguard the two-level information, and the recovered images exhibit exceptional clarity.