Secure and reliable blockchain-based eBook transaction system for self-published eBook trading.

As eBook readers have expanded on the market, various online eBook markets have arisen as well. Currently, the online eBook market consists of at least publishers and online platform providers and authors, and these actors inevitably incur intermediate costs between them. In this paper, we introduce a blockchain-based eBook market system that enables self-published eBook trading and direct payments from readers to authors without any trusted party; because authors publish themselves and readers purchase directly from authors, neither actor incurs any intermediate costs. However, because of this trustless environment, the validity, ownership and intellectual property of digital contents cannot be verified and protected, and the safety of purchase transactions cannot be ensured. To address these shortcomings, we propose a secure and reliable eBook transaction system that satisfies the following security requirements: (1) verification of the ownership of each eBook, (2) confidentiality of eBook contents, (3) authorization of a right to read a book, (4) authentication of a legitimate purchaser, (5) verification of the validity and integrity of eBook contents, (6) safety of direct purchase transactions, and (7) preventing eBook piracy and illegal distribution. We provide practical cryptographic protocols for the proposed system and analyze the security and simulated performance of the proposed schemes.

Purification and characterization of ginsenoside Ra-hydrolyzing beta-D-xylosidase from Bifidobacterium breve K-110, a human intestinal anaerobic bacterium.

Beta-D-Xylosidase (EC 3.2.1.37) has been purified from ginsenoside Ra-metabolizing Bifidobacterium breve K-110, which was isolated from human intestinal microflora. beta-D-Xylosidase was purified to apparent homogeneity by a combination of ammonium sulfate precipitation, QAE-cellulose, butyl-toyopearl, hydroxyapatit and Q-Sepharose column chromatographies with the final specific activity of 51.8 micromol/min/mg. Molecular weight of beta-D-xylosidase is 49 kDa by SDS-PAGE and gel filtration, which consisted of a single subunit. beta-D-Xylosidase showed optimal activity at pH 5.0 and 37 degrees C. The purified enzyme was potently inhibited by PCMS. beta-D-Xylosidase acted to the greatest extent on p-nitrophenyl-beta-D-xylopyranoside, followed by ginsenoside Ra1 and ginsenoside Ra2. This enzyme hydrolyzed xylan to xylose, but did not act on p-nitrophenyl-beta-glucopyranoside, p-nitrophenyl-beta-galactopyranoside or p-nitrophenyl-beta-D-fucopyranoside. These findings suggest that this is the first reported purification of ginsenoside-hydrolyzing beta-D-xylosidase from an anaerobic Bifidobacterium sp.