BCAS: A blockchain-based ciphertext-policy attribute-based encryption scheme for cloud data security sharing

It is the most important and challenging problem to share the data safely in cloud computing. Some so-called trusted third parties may also infringe users’ data privacy. It is an urgent problem for data owners to share data safely with the designated users rather than the third party or other users. Traditional encryption schemes utilize different keys to produce multiple encrypted copies of the same data for users. It is no longer applicable for cloud data sharing security. Attribute-based encryption can solve above problems, but it needs to rely on trusted third parties to protect the users’ privacy. In this article, in order to address the above problems, we propose a blockchain-based ciphertext-policy attribute-based encryption scheme for cloud data secure sharing without relying on any trusted third parties. Blockchain-based ciphertext-policy attribute-based encryption scheme can protect the rights and security of data owner. Compared with existing cloud security schemes, the proposed scheme has more advantages in terms of the six aspects: (1) data owners have the authority to decide who can decrypt the data; (2) the operations of users are retained permanently, and all records are tamper-proof; (3) our proposed scheme has the characteristic of “one-to-many” encryption, and data is encrypted only once; (4) our scheme does not rely on any trusted third party; (5) in terms of the discrete logarithm problem and decisional q parallel-bilinear Diffie–Hellman exponent problem, we prove that our proposed scheme is secure; and (6) experiment shows that our proposed scheme is more efficient than the comparative scheme.

A Securities Settlement Model Using Blockchain Technology for Central Securities Depository

Post-trade securities settlements entered the electronic age between 1980 and 2000. The introduction of technologies such as secure electronic messaging, and improvements in database technology, enabled the inception of central securities depositories (CSDs) as trusted third parties or intermediaries within the securities settlements post-trade landscape. The study reported in this chapter has a focus on CSDs and the application of the blockchain technology to securities settlements. The objective is to develop a model for securities settlements using blockchain technology for a CSD, as currently, globally, no CSD has introduced a production-ready blockchain-based solution for securities settlements. A conceptual model was created from the reported literature that was evaluated by international post-trade securities professionals. The findings have resulted in the acceptance of the main components of the model, with a focus on the cost of the solution, and with the identification of prerequisites to such a solution (e.g., legal/regulatory enablement).

A Watermarking Protocol Based on Blockchain

Digital watermarking can be used to implement mechanisms aimed at protecting the copyright of digital content distributed on the Internet. Such mechanisms support copyright identification and content tracking by enabling content providers to embed perceptually invisible watermarks into the distributed copies of content. They are employed in conjunction with watermarking protocols, which define the schemes of the web transactions by which buyers can securely purchase protected digital content distributed by content providers. In this regard, the “buyer friendly” and “mediated” watermarking protocols can ensure both a correct content protection and an easy participation of buyers in the transactions by which to purchase the distributed content. They represent a valid alternative to the classic “buyer and seller” watermarking protocols documented in the literature. However, their protection schemes could be further improved and simplified. This paper presents a new watermarking protocol able to combine the “buyer friendly” and “mediated” design approach with the blockchain technology. The result is a secure protocol that can support a limited and balanced participation of both buyers and content providers in the purchase transactions of protected digital content. Moreover, the protocol can avoid the direct involvement of trusted third parties in the purchase transactions. This can reduce the actual risk that buyers or sellers can violate the protocol by illicitly interacting with trusted third parties. In fact, such peculiarities make the proposed protocol suited for the current web context.

Blockchain, consensus, and cryptography in electronic voting

Motivated by the recent trends to conduct electronic elections using blockchain technologies, we review the vast literature on cryptographic voting and assess the status of the field. We analyze the security requirements for voting systems and describe the major ideas behind the most influential cryptographic protocols for electronic voting. We focus on the great importance of consensus in the elimination of trusted third parties. Finally, we examine whether recent blockchain innovations can satisfy the strict requirements set for the security of electronic voting.