Four students from Carnegie Mellon, and MIT have written a paper entitled, “Beaver: A Decentralized Anonymous Marketplace with Secure Reputation.” The paper has come to many spotlights on cryptocurrencies this week. It tells tales of an advanced marketplace with the ultimate privacy in mind that’s main focus is reputations based on free market associations.
They tell about how an anonymous market could establish a reliable reputation system that is strong enough to avoid Sybil attacks to vendor feedback and keeping customers privacy above all. The marketplace’s ‘fails’ are gone over in regards to some other decentralized marketplaces like OpenBazaar and Silk Road 1. The framework for OpenBazaar does not support ‘privacy-centric techniques’ like Tor does, because of the UDP protocol the report says.
With this fault, other markets could be victim of Sybil attacks. Simply put, this means that one user could create enough separate identities to use for submitting negative feedback to a vendor with high positive feedback, thus lowering they’re vendor reputation.
“In this paper, we introduce a formal model for decentralized anonymous marketplace (DAM), and design Beaver, a Sybil-resistant DAM. Beaver is designed with e-commerce in mind, and consists of three types of participants: customers, vendors, and network miners. Unlike most existing approaches, participation in Beaver is free, open, and does not use a trusted third party. From the perspective of customers and vendors, Beaver behaves nearly identically to existing e-commerce systems such as Amazon and eBay,” the White paper read.
Beaver says its structure could make and ground a better reputation system and offer highly strengthened anonymity for its users. In the concept of a marketplace like Beaver, it uses an anonymous payment system with numerous cryptographic basics. Zerocash is referred to in the paper, which is an extension that adds more of a barrier of privacy to the BTC protocol that was proposed first by Mathew D. Green, Ian Miers, and Christina Garman. Due to the high anonymity, Beaver believes it enables a better reputation system free from customers that are scared off by false negative feedbacks left with malicious intent.
Beaver makes transactions and reviews public, but promises that any details of these transactions are always going to remain anonymous. Sybil attacks rely more on user identities and user history. This is why Beaver is going to keep this part private, to stop anyone from even wanting to use such an attack. Beaver is only in theory at this point, and nothing has been discussed further about putting it into practise. Further the authors of the paper never said if they plan to even move forward with Beaver at all; but one of the authors did post on a dark net subreddit.
“Hi, one of the authors here. We are working on getting some performance numbers at the moment, but we would love to actually start implementing them, and make it something real!”
Following this comment, another author explains, “performance numbers in terms of quickness and in terms of blockchain size for the operations in Beaver.”
The developers also mention the use of zero proof knowledge and ring signatures which are used in privacy-centric cryptocurrencies such as Monero.
For now, this is only a twinkle in the author’s eyes. Even if they decided to start today, it would be some time before Beaver had a stable home on the Dark Net; not to mention that it would take even longer to reach the height that OpenBazaar has built itself to. Additionally, OpenBazaar is planning on adding privacy-centric features soon like Tor support.