Wasabi Research Club #4 - Dining Cryptographers
Channel: Wasabi Wallet
Date: 27/01/2020

In today's episode the concept of Dining Cryptographers networks (DCNets) is introduced and explained. DCNets are a solution to the Dining Cryptographers problem, in which participants want to determine if someone paid without revealing the identity of the payer. The protocol involves participants flipping coins and creating shared secrets, which are XORed together to determine if someone paid. The section provides a visual example of how the protocol works. The video also discusses the challenges and limitations of DCNets, including the need for significant bandwidth and the potential for system collapse if participants don't cooperate properly. Despite these drawbacks, the video suggests that DCNets can be useful for certain applications, such as anonymous broadcasting of outputs for quantum participants. Finally, the participants discuss related topics such as key generation, encrypted messaging using XOR keys, bootstrapping in decentralized networks, and the concept of unobservability in the context of the Dining Cryptographers protocol. Later the conversation covers different networks like the DC network, Locking Net, and Neem network. Plans for future topics include Coin Shuffle++, Cash Fusion, and privacy quantification papers. Renaming the Wasabi Research Club to Dining Bitcoiners is considered but dismissed due to the effort involved in updating links. The video ends with appreciation for an NFC payment that covered their dinner.

Topic: Dining Cryptographer Networks - http://homepages.herts.ac.uk/~comqjs1/Dining.pdf
Code: nopara73 - https://github.com/nopara73/DiningCryptographerSimulation

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00:00 Intro

00:40 Weekly recap.

02:11 The premise of Dining Cryptographers.

05:08 Example: Playing Dining Cryptographers in chat.

10:29 XOR'd secrets / Public message.

13:12 Why does this work?

14:37 Why is the sum of public messages always even?

16:04 Summary of the protocol.

17:14 Generalising Dining Cryptographer Networks.

17:58 Example: Logism.

25:03 Problems with DC Nets.

27:05 Summary of DC Nets.

27:31 Discussion.

29:01 Is this key-exchange protocol practical?

33:10 Using DC Nets for messaging.

37:45 How do peers establish secure channels?

41:04 BIP-151: Peer-to-Peer Communication Encryption.

44:11 Attacks against anonymity in DC Nets.

48:22 Why is this an unobservable anonymity system?

49:20 Define observability.

52:03 Observability/Unlinkability and onion-routing.

56:19 Scalability of the DC Net protocol.

58:06 What incentivises malicious actors?

59:24 Mainstream uses for DC Nets.

01:01:36 Conclusion. / Next week's topics.