ShadowCash Whitepaper


Abstract­We introduce Shadowcash, an anonymous cryptographic transaction protocol: Anonymous
transactions are implemented using traceable ring signatures[5], which utilise a non­interactive zero
knowledge proof[6].

We believe privacy is a human right ­ as enshrined in article 12 of the Universal Declaration of
Human Rights of the United Nations. Transactions of value are an essential part of our daily lives.
As such we strive to provide you with tools to transact in confidence[1].
E­cash systems, or virtual currencies[2], have become a very common way to transact due to the
many benefits they hold over traditional methods of exchange. One of the largest problems for
virtual currencies is preventing double­spending, where a currency holder sends the same coins to
multiple recipients. Bitcoin solves this problem using the blockchain, a public record of all
transactions in the system. By viewing the blockchain, all participants in the currency can see the
current state of the system at the same time, thus the double­spending problem is solved. However,
adding the blockchain causes a severe reduction of the anonymity and privacy of the participants in
the currency[3]. As the blockchain is public, anyone can see the transactions and total holdings of
participants, unless suitable precautions are taken.

2. Overview
In this paper we will present our anonymous cryptographic transaction protocol which utilises:
dual­key stealth addresses, traceable ring signatures and non­interactive zero knowledge proofs.
We prove how our scheme introduces a much higher level of privacy and anonymity to the network
while still preserving the core principles of trustless decentralization, unforgeability and
double­spend prevention. We will also present performance data of our scheme which includes
proof sizes, signature generation times and verification times.
Finally, we will present planned future improvements to the current scheme. We present this paper
as a first draft towards receiving peer review.

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ShadowCash Whitepaper