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Exchange of information through the web took place inside a trusted environment and thus user privacy was assured by default. Nowadays, ensuring user privacy is becoming one of the most desirable features of new technology, and Blockchain is not an exception. The Blockchain is a decentralized technology, open, and public platform where all transactions are stored and viewed from nodes, an approach known as "Web of Trust." Although these transactions tend to be anonymous but in the case of the banking sector, user privacy requires special attention. In centralized systems, the implementation of privacy is no longer a challenge, using a hierarchical approach such as Public Key Infrastructure. This paper presents a broad landscape and state of art of user transaction privacy in Blockchain technology using the Web of Trust approach. Furthermore, we present a novel approach using the Public Key Infrastructure for assuring user privacy adding an optionally encrypted field in blocks in transactions. We have used Bithomp, as a free and open-source tool with the Testnet platform, and Ripple as the best known in the implementation of the payment system to implement the proposed approach. The paper concludes with the strengths and limitations of the proposed approach. [ABSTRACT FROM AUTHOR]

Anonymity and privacy in the electoral process are mandatory features found in any democratic society, and many authors consider these fundamental civil liberties and rights. During the election process, every voter must be identified as eligible, but after casting a vote, the voter must stay anonymous, assuring voter and vote unlinkability. Voter anonymity and privacy are the most critical issues and challenges of almost all electronic voting systems. However, vote immutability must be assured as well, which is a problem in many new democracies, and Blockchain as a distributed technology meets this data immutability requirement. Our paper analyzes current solutions in Blockchain and proposes a new approach through the combination of two different Blockchains to achieve privacy and anonymity. The first Blockchain will be used for key management, while the second will store anonymous votes. The encrypted vote is salted with a nonce, hashed, and finally digitally signed with the voter's private key, and by mixing the timestamp of votes and shuffling the order of cast votes, the chances of linking the vote to the voter will be reduced. Adopting this approach with Blockchain technology will significantly transform the current voting process by guaranteeing anonymity and privacy. [ABSTRACT FROM AUTHOR]