A blockchainbased loan overprevention mechanism Information sharing solves the problem of information asymmetry between banks to a certain extent, but it also brings about the leakage of customer privacy. Therefore, how to protect data privacy while sharing data is an urgent issue. Blockchain protects the privacy of accounts and data while sharing data. Therefore, we propose a blockchainbased loan overprevention mechanism. The program can hide the customer loanrepayment amount and thus protect the customeru0027s privacy; we prove that the customeru0027s loan amount is within a certain range and does not exceed the remaining loanable amount via a range proof. In order to share customer loan information between banks, we store the commitment of customersu0027 amounts in the blockchain, and banks can obtain relevant information directly from the chain, which also reduces the amount of communication between banks. Finally, we implement the model and performe a performance analysis.

Security and Privacy on Blockchain Blockchain offers an innovative approach to storing information, executing transactions, performing functions, and establishing trust in an open environment. Many consider blockchain as a technology breakthrough for cryptography and cybersecurity, with use cases ranging from globally deployed cryptocurrency systems like Bitcoin, to smart contracts, smart grids over the Internet of Things, and so forth. Although blockchain has received growing interests in both academia and industry in the recent years, the security and privacy of blockchains continue to be at the center of the debate when deploying blockchain in different applications. This paper presents a comprehensive overview of the security and privacy of blockchain. To facilitate the discussion, we first introduce the notion of blockchains and its utility in the context of Bitcoin like online transactions. Then we describe the basic security properties that are supported as the essential requirements and building blocks for Bitcoin like cryptocurrency systems, followed by presenting the additional security and privacy properties that are desired in many blockchain applications. Finally, we review the security and privacy techniques for achieving these security properties in blockchainbased systems, including representative consensus algorithms, hash chained storage, mixing protocols, anonymous signatures, noninteractive zeroknowledge proof, and so forth. We conjecture that this survey can help readers to gain an indepth understanding of the security and privacy of blockchain with respect to concept, attributes, techniques and systems.