Other Privacy-Preserving Payments
In what follows, we provide an overview of privacy-preserving payment systems that are crafted for the context of anonymous taxation of investments, stocks, and bank account balances.
In , Xu et al. propose a scheme addressing privacy issues related to stock market accounts, by offering anonymous and taxable stock market trading accounts. This system addresses the problem of tax reporting in an anonymous system. Each user anonymously hold funds (or stocks), and the taxable amounts must be reported to the taxation authority.
Here, investors have normal certificates, which they may use to generate a conditionally anonymous certificate (CAC) that represents their anonymous accounts. These CACs are recognized by the Stock Exchange Center (SEC) and used to verify signed orders indicating stock market-related activities. They are normally unlinkable to their original certificates. However, in cases of misbehavior, a CAC may be opened by an appropriate authority to reveal the identity of the owner. During taxation, the SEC prepares reports for each anonymous account and provides them to the tax authority, to which the user can prove ownership of and pay the appropriate taxes. The system leverages user-generated anonymous credentials from a public credential to validate anonymous transactions.