Wasabi Research Club #5 - CoinShuffle++ with Tim Ruffing (Part 1)

Описание: In today's episode Tim Ruffing introduces the CoinShuffle++ protocol and explains its key components. He describes how the protocol uses power sums and polynomial roots to ensure secure messaging between participants. The protocol consists of four stages: Dimi Hellman key exchange, commitment, DC net, and confirmation. The protocol handles malicious peers by revealing secret keys and excluding them in the next round. Ruffing also highlights the scalability of the CoinShuffle++ protocol, as it can accommodate a large number of participants and complete the process in a relatively short time. The use of dice mix enhances the efficiency of the protocol compared to its predecessor, CoinShuffle. Futher Tim dives into the challenges of implementing CoinShuffle++, a decentralized protocol for coinjoining cryptocurrencies. He highlights the issues caused by varying internet connection speeds and round communication, leading to slower performance. Ruffing also discusses concerns about the negotiation process and cryptography affecting communication speed. Additionally, he acknowledges the complexity of the topic and expresses a desire to simplify it for wider understanding and implementation. Overall, Ruffing emphasizes the importance of maintaining privacy in peer-to-peer transactions and the potential of cryptography in various applications.

Topic: In this meeting we discussed CoinShuffle++ with one of the authors, Tim Ruffing.

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Website: https://WasabiWallet.io
Blog: https://blog.WasabiWallet.io
Documentation: https://docs.WasabiWallet.io
GitHub: https://github.com/zkSNACKs/WalletWasabi
Podcast: https://anchor.fm/Wasabikas
YouTube:    / wasabiwallet  

00:00 Intro

01:17 Weekly recap.

02:27 The cryptographers at dinner. (DC nets, Chaum)

06:08 Message collision in DC networks.

07:28 Malicious actors in DC networks.

08:41 Coinshuffle++. / Dicemix protocol / 4 + 2f rounds.

12:53 Malicious actors in Dicemix.

13:17 Example of Dicemix round.

15:41 Knapsack and unequal amounts.

19:57 What is required to determine input amounts?

21:00 Fixed messages.

30:31 Generic attacks.

33:47 How to understand Coinshuffle++.

37:46 Base case: 4-bit message and 3 participants.

40:29 Implementation differences in Coinshuffle and Coinshuffle++.

44:46 Broadcast protocol for Coinshuffle. / Complexity in Coinshuffle.

48:34 Complexity in the communication layer. / Why not use Tor?

53:47 How does the protocol prevent learning of IP addresses of participants?

58:32 How does the 20 second benchmark change with Tor?

01:00:46 2 minute timeouts in Wasabi.

01:02:44 Using new negotiations. / Tor streams.

01:04:44 When 1 round fails.

01:05:47 Would Wasabi be safer if it used a Coinshuffle model?

01:09:03 CashShuffle vs CoinShuffle.

01:13:12 Coinshuffle vs DC net.

01:16:56 Using the pseudocode and building blocks to understand Coinshuffle++.

01:18:13 Do you think a p2p network using Hashcash is a flawed idea? / Bitmessage.

01:19:40 Conclusion.

01:21:44 Decentralised p2p communication is required.