Blockchains offer a decentralized, immutable and verifiable ledger that can record transactions of digital assets, provoking a radical change in several innovative scenarios, such as Smartcities, eHealth or eAdministration. However, blockchains are subject to different scalability, security and potential privacy issues, such as transaction linkability, crypto-keys management (e.g. recovery), on-chain data privacy, or compliance with privacy regulations (e.g. GDPR). In this regard, novel privacy-preserving solutions for blockchain based on crypto-privacy techniques are emerging to deal with those challenges and empowering users with mechanisms to become anonymous and take control of their personal data during their digital transactions of any kind in the ledger, following a Self-Sovereign Identity (SSI) model. In this sense, this paper performs a systematic review of the current state of the art on privacy-preserving research solutions and mechanisms in blockchain, as well as the main associated privacy challenges in this promising and disrupting technology. The survey covers privacy techniques in public and permissionless blockchains, e.g. Bitcoin and Ethereum, as well as privacy-preserving research proposals and solutions in permissioned and private blockchains. Diverse blockchain scenarios are analyzed, encompassing, eAdministration, eHealth, cryptocurrencies, Smart cities, and Cooperative ITS.
BERNAL BERNABE Jorge;
CANOVAS SANCHEZ Jose Luis;
HERNANDEZ RAMOS Jose Luis;
TORRES Rafael;
SKARMETA Antonio;
2019-11-21
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
JRC111879
2169-3536 (online),
https://ieeexplore.ieee.org/document/8888155,
https://publications.jrc.ec.europa.eu/repository/handle/JRC111879,
10.1109/ACCESS.2019.2950872 (online),
