Synthesis and biological evaluation of water-soluble derivatives of chiral gossypol as HIV fusion inhibitors targeting gp41.

A series of novel or known water-soluble derivatives of chiral gossypol were synthesized and screened in vitro for their anti-HIV-1 activity. (-)-gossypol derivative was more active against HIV-1 than the corresponding (+)-gossypol derivative, respectively. Among these derivatives, d-glucosamine derivative of (-)-gossypol, oligopeptide derivative of (-)-gossypol and taurine derivative of (-)-gossypol, such as compounds 1a, 3a and 14a, showed significant inhibitory activities against HIV-1 replication, HIV-1 mediated cell-cell fusion and HIV gp41 6-helix bundle formation as some amino acid derivatives of (-)-gossypol.

Synthesis and anti-H5N1 activity of chiral gossypol derivatives and its analogs implicated by a viral entry blocking mechanism.

A series of chiral gossypol derivatives and its analogs were synthesized and tested in vitro for their anti-H5N1 activity. Interestingly, (+)-gossypol derivatives and its analogs were more active against H5N1 than the corresponding (-)-gossypol derivatives and its analogs. Through a simple chemical modification with amino acids, less active chiral gossypol could be converted into more active derivatives, and most of chiral gossypol derivatives were more potent against H5N1 than 1-adamantylamine. With regard to the mechanism of action, chiral gossypol derivatives and its analogs might impair the virus entry step of cell infection, likely targeting to HA2 protein.

Exfiltrating data from an air-gapped system through a screen-camera covert channel.

In recent years, many methods of exfiltrating information from air-gapped systems, including electromagnetic, thermal, acoustic and optical covert channels, have been proposed. However, as a typical optical channel, the screen-camera method has rarely been considered; it is less covert because it is visible to humans. In this paper, inspired by the rapid upgrades of cameras and monitors, we propose an air-gapped screen-camera covert channel with decreased perceptibility that is suitable for complex content. Our method exploits the characteristics of the human vision system (HVS) and embeds quick response (QR) codes containing sensitive data in the displayed frames. This slight modification of the frames cannot be sensed by the HVS but can be recorded by the cameras. Then, using certain image processing techniques, we reconstruct the QR codes to some degree and extract the secret data with a certain level of robustness due to the error correction capacity of QR codes. In the scenario to which our method applies, we assume that a program has been installed in the target system and has the authority to modify the frames without affecting the normal operations of valid users. Cameras, such as web cameras, surveillance cameras and smartphone cameras, can be receivers in our method. We illustrate the applicability of our method to frames with complex content using several different cover images. Experiments involving different angles between the screen and the camera were conducted to highlight the feasibility of our method with angles of $ 0^{\circ}, 15^{\circ}$ and $30^{\circ} $.

Multiple security anti-counterfeit applications to QR code payment based on visual secret sharing and QR code.

In this paper, we propose a novel mechanism for QR code security anti-counterfeit based on the fusion of visual secret sharing (VSS) and QR code (called VSSQR scheme), which can greatly improve the security of QR code payment. Due to different application scenarios, the background security anti-counterfeit application and the prospects security anti-counterfeit application are shown for QR code payment authentication. The basic idea of the two applications can be characterized as follows. First, two QR code shares that contain the information of the merchant can be generated based on VSSQR scheme with an original secret image. Second, the secret image can be revealed by stacking two QR code shares to obtain the original information. Finally, whether the stacking result is the same as the original secret image or not can determine the authenticity of QR code share used for payment. The analyses show the security of our method. The applications are conducted to show the effectiveness and practicability.

Ramp secret image sharing.

Secret image sharing (SIS) belongs to but differs from secret sharing. In general, conventional (k,n) threshold SIS has the shortcoming of "all-or-nothing". In this article, first we introduce ramp SIS definition. Then we propose a (k1,k2,n) ramp SIS based on the Chinese remainder theorem (CRT). In the proposed scheme, on the one hand, when we collect any k1 or more and less than k2 shadows, the secret image will be disclosed in a progressive way. On the other hand, when we collect any k2 or more shadows, the secret image will be disclosed losslessly. Furthermore, the disclosing method is only modular arithmetic, which can be used in some real-time applications. We give theoretical analyses and experiments to show the effectiveness of the proposed scheme.

High capacity reversible data hiding in MP3 based on Huffman table transformation.

In practice, most audio files such as MP3 and AAC are stored and transmitted in the form of compressed files, which can serve as the cover in audio steganography. Currently, the prevailing audio steganography methods are not ideal because of the drawbacks. Some are characterized by low capacity while others are irreversible. In this paper, we propose a method to embed secret messages in MP3 encoding. Our strategy is to hide the information by Huffman table transformation. We extract secret information by analyzing side information. Experimental results show that our method can greatly improve the steganographic capacity with low distortion and high security. Meanwhile, it featured with higher decoding rate and reversible over some state-of-the-art methods.

Fluorescent detection and imaging of Hg(2+) using a novel phenanthroline derivative based single- and two-photon excitation.

A novel phenanthroline derivative, 4-[4-(N-methyl)styrene]-imidazo[4,5-f][1,10]phenanthroline-benzene iodated salt (MSIPBI), was synthesized, and the linear absorption and fluorescent spectra of MSIPBI in different solvents were investigated. The photophysical properties in unbound and in ligand-metal complexes were evaluated by UV absorption and one- and two-photon fluorescent spectra, and the quantum yields, two-photon active cross-sections and the binding constant of dye-metal were calculated. The results indicated that MSIPBI has a large Stokes shift (more than 167nm), and the dye was selective and sensitive for the detection of Hg(2+) with a two-photon active cross-section of 55.5GM in tris-HCl buffer solution at 800nm. Furthermore, the results of the fluorescence microscopy imaging indicated that MSIPBI is an efficient fluorescent probe for the detection of Hg(2+) in living cells by one- and two-photon excitation. Moreover, the experiments of determination Hg(2+) in river water and tap water were finished.