Steganography and authentication in image sharing without parity bits

Recently, a polynomial-based (k, n) steganography and authenticated image sharing (SAIS) scheme was proposed to share a secret image into n stego-images. At the same time, one can reconstruct a secret image with any k or more than k stego-images, but one cannot obtain any information about the secret from fewer than k stego-images. The beauty of a (k, n)-SAIS scheme is that it provides the threshold property (i.e., k is the threshold value), the steganography (i.e., stego-images look like cover images), and authentication (i.e., detection of manipulated stego-images). All existing SAIS schemes require parity bits for authentication. In this paper, we present a novel approach without needing parity bits. In addition, our (k, n)-SAIS scheme provides better visual quality and has higher detection ratio with respect to all previous (k, n)-SAIS schemes.     

Lightweight and flexible key distribution schemes for secure group communications

Wireless Networks - Key distribution is one of the most fundamental cryptographic primitives that can establish secure group communications in both centralized and distributed networks. A one-time...     

Determination of isopropyl-9H-thioxanthen-9-one in packaged beverages by solid-phase extraction clean-up and liquid chromatography with tandem mass spectrometry detection

A simple method was developed and validated for the trace determination of 2-isopropylthioxanthone (ITX) in packaged drinks. Samples were extracted from the food matrix using acetonitrile:water (60:40, v/v), and further subjected to clean-up and preconcentration using solid-phase extraction prior to analysis by liquid chromatography-tandem mass spectrometry using multiple reaction monitoring (MRM) mode. The use of 2-isopropyl-[(2)H7]thioxanthen-9-one was incorporated into the method as an internal standard. Excellent 3-day interday precision data (RSD 0.72%, n=10), and intraday precision data (RSD 0.52%, n=10) were obtained on a 0.10 microg/L standard solution. Spiked samples (n=8) were used to gauge the accuracy of the method at the concentration levels of 2.5, 100, and 500 microg/kg in food; recoveries ranged from 97.0 to 103.0%. These excellent validation data suggest the exciting possibility of using this method for the determination of low levels of ITX migrating from printed food packaging materials into beverages with a method quantitation limit of 0.50 microg/kg. For the first time, analysis on a range of milk, juice, tea and yoghurt drinks, as well as their respective food packaging materials were performed for comparative studies on their ITX content.     

UMKESS: user-oriented multi-group key establishments using secret sharing

Wireless Networks - With the rapid development of group-oriented services, there are more and more multi-group communications in which users may join multiple group communications simultaneously....     

Cryptanalysis of the blind signatures based on the discretelogarithm problem

Carmenisch et al. proposed a blind signature scheme based on the discrete logarithm during the rump session of Eurocrypt '94. Horster et al. generalised this approach to design the Meta blind signature schemes. The author points out that these schemes cannot provide true blind signatures     

Digital signature for Diffie-Hellman public keys without using aone-way function

The author proposes digital signature schemes without using a one-way function to sign Diffie-Hellman public keys. The advantage of this approach is, instead of relying overall security on either the security of the signature scheme or the security of the one-way function, the security of this proposed scheme is based on the discrete logarithm problem     

Centralized Group Key Establishment Protocol without a Mutually Trusted Third Party

The type of centralized group key establishment protocols is the most commonly used one due to its efficiency in computation and communication. A key generation center (KGC) in this type of protocols acts as a server to register users initially. Since the KGC selects a group key for group communication, all users must trust the KGC. Needing a mutually trusted KGC can cause problem in some applications. For example, users in a social network cannot trust the network server to select a group key for a secure group communication. In this paper, we remove the need of a mutually trusted KGC by assuming that each user only trusts himself. During registration, each user acts as a KGC to register other users and issue sub-shares to other users. From the secret sharing homomorphism, all sub-shares of each user can be combined into a master share. The master share enables a pairwise shared key between any pair of users. A verification of master shares enables all users to verify their master shares are generated consistently without revealing the master shares. In a group communication, the initiator can become the server to select a group key and distribute it to each other user over a pairwise shared channel. Our design is unique since the storage of each user is minimal, the verification of master shares is efficient and the group key distribution is centralized. There are public-key based group key establishment protocols without a trusted third party. However, these protocols can only establish a single group key. Our protocol is a non-public-key solution and can establish multiple group keys which is computationally efficient.     

Bounded-to-unbounded poker game

The bounded-to-unbounded poker game is a fair poker game that can be played over the Internet. It allows both dealer and player to distribute cards in a fair and secure manner. In addition, the presented protocol assumes that the player is computationally bounded: however, the dealer is computationally unbounded