The three primary requirements in privacy coin are sender anonymity, receiver anonymity, and transaction amount obscurity. In the process of achieving these three requirements, it can result in some side-effects. Some of the side-effects include large blockchain sizes, unpruneable blockchain, unverifiable total coin mintage, and complicated protocol. In this paper, we propose a coin privacy solution that fulfills these three requirements without side-effects. Compared to other solutions, our solution has a bigger anonymity set, easier to understand, and comes with prunable blockchain. However, transactions involving fractionation amount are rounded up to the nearest available denomination. This rounding up is acceptable because it is a similar problem with cash that been used for centuries. Our protocol is an extension of bitcoin P2PKH and CoinJoin features. The CoinJoin is secured with a CoinJoinID, which cryptographical hard to reproduce. We also have proven the security of the pruning process. Other related issues are also described in this paper.

隐私硬币中的三个主要要求是发送者匿名，接收者匿名和交易金额模糊。在实现这三个要求的过程中，可能会产生一些副作用。一些副作用包括较大的区块链大小，不可修剪的区块链，不可验证的总硬币铸币量以及复杂的协议。在本文中，我们提出了一种硬币隐私解决方案，该解决方案可以满足这三个要求而没有副作用。与其他解决方案相比，我们的解决方案具有更大的匿名集，更易于理解，并且带有可修剪的区块链。但是，涉及细分金额的交易会四舍五入到最接近的可用面额。这种舍入是可以接受的，因为这与使用了多个世纪的现金有类似的问题。我们的协议是比特币P2PKH和CoinJoin功能的扩展。CoinJoin通过CoinJoinID进行保护，该ID很难通过密码进行复制。我们还证明了修剪过程的安全性。本文还描述了其他相关问题。