E-cash was invented in 1982 by David Chaum as an anonymous cryptographic electronic cash system based on blind signatures. It is not a decentralized form of money as Bitcoin. It requires trust on the server or Mint issuing the e-cash tokens and validating the transactions for preventing double spends. Moreover, the users also need to trust the Mint to not debase the value of e-cash tokens by Minting an uncontrolled number. In particular, this is critical for e-cash tokens representing a note of another asset as a currency, or bitcoin, or another cryptocurrency. Thus it would be suitable to implement a public auditing system providing a proof of reserves that ensures that the Mint is not engaging into a fractional reserve system. In this article we describe how to implement a proof of reserves system for Chaumian Mints. The protocol also provides a proof of non-double spends.

翻译：电子现金由 David Chaum 于1982年提出，是一种基于盲签名的匿名密码学电子现金系统。它不同于比特币等去中心化货币形式，需要依赖服务器或铸币厂发行电子现金代币并验证交易以防止双重花费。此外，用户还需信任铸币厂不会通过无限量铸造来降低电子现金代币的价值。当电子现金代币代表其他资产（如法定货币、比特币或其他加密货币）时，这一信任问题尤为关键。因此，实现一个能够提供准备金证明的公共审计系统显得十分必要，以确保铸币厂不会开展部分准备金制度。本文描述了如何为 Chaumian 铸币厂实现准备金证明系统，该协议同时提供了双重花费的防止证明。