Conference Kickoff

The second renaissance of ecash

The revival of ecash is unlocking a new frontier for digital payments, driving innovation across the Bitcoin ecosystem. In this talk, I will explore the pioneering work being done by developers building applications with this technology. We will examine the cryptosystem behind the Cashu protocol and discuss potential improvements, paving the way for more advanced Chaumian ecash systems in the future.

Federated eCash mints 101

Curious about Federated eCash Mint but not sure what it’s all about? In this session, we’ll break down how it works, what you can actually do with it, and why it matters. From its privacy features to real-world use cases, we’ll cover everything you need to know in simple, no-nonsense terms. Whether you’re completely new or just looking to get a better understanding, this talk will help you figure out how Federated eCash Mint can make a difference.

Ecash for Other Stuff

The rational, challenges, and optimizations of using ecash in Wasabi Wallet as anonymous api access right management tool.

Nutsack: Unsiloed Data, Unsiloed Money

NIP-60 + NIP-61 bring interoperable wallets to any nostr app, along with immediate, verifiable zaps.

How to build a Fedimint wallet in 20 minutes (without Rust)

The Fedimint Web SDK just launched. Join Alex Lewin for a deep dive into what it enables for ecash payments on the web.

Ecash in non-permissive environments

Ecash is a revolutionary technology, but would it work in a SHTF situation? How would people transact during a national blackout or if a government severed a country's international internet connection?

Fedimint Consensus

How to design a low latency Byzantine Fault Tolerant system for constant performance with respect to the number of nodes.

Could STARK proofs be good for Cashu ?

What if we could create a mint that could be penalized if it doesn't play by the rules? That's where STARK proofs come in. We will speak about Coconut, an experimental Mint and Wallet, written in Zig, aiming to explore potential applications of ZK proofs for Cashu protocol. We will think about how STARK proofs could potentially be used to reduce trust assumptions of the protocol.

Fedimint Footprints: Exploring What's Visible

A brief exploration of publicly available data from Fedimints using an open-source tool, Fedimint Observer.

Nostr Wallet Connect and Ecash

In this workshop, you'll learn how to add lightning to your project easily by combining ecash with Nostr Wallet Connect

Building Ecash Support into Web Apps

A talk on integrating and supporting ecash in web apps

Federation Stats

Short presentation on Fedi's white-glove federations

CDK Deep Dive

In this workshop, we’ll provide an overview of the Cashu Dev Kit (CDK), focusing on both the mint and wallet components. We’ll walk you through how to set up CDK in your project and how to use it to create a basic wallet. This session is practical and hands-on, using real-world examples to help you understand the core concepts and functionalities of the Cashu Dev Kit. By the end of the workshop, you’ll have built a simple yet functional wallet and gained a solid understanding of how to leverage CDK in your projects.

Un-custody: A New Approach To Permissionless Transactions

There are currently two main approaches to Bitcoin custody: self-custody, e.g. the use of non-custodial wallets or cold storage, and centralized custody, through trusted 3rd parties and multisignature schemes. In an abstracted environment (which maintains Bitcoin finality and proximity) there is a third option: un-custody - or custody-by-consensus - a custody scheme completely foregoing cryptographic proofs. This talk explores un-custody and its benefits and applications, particularly with respect to DeFi systems like ecash implementations.

Hackathon Kick-off

Get an overview of the prizes and judging criteria, and find your team to start working at the hackathon kickoff session.

Day 2 Kickoff

Cashu on Shopstr, NIP-60 Cashu Wallet

Cashu on Shopstr: An overview of how Cashu is used throughout the Shopstr marketplace Nostr client. NIP-60 Cashu Wallet: A workshop going over how to implement a Nostr-based Cashu wallet.

P2P Transmission Methods

Copy-pasting is easy enough... Animated QR codes are cool too! What else can we do? In this workshop we'll explore different ways of transmitting ecash from one device to another, particularly mobile devices in low-connectivity environments. - Text-based transmission (copy-paste & send) - Visual transmission (animated QR codes) - Audio transmission (wtf? is this even possible?)

Fedimint Lightning Gateway v2

This presentation will describe the evolution of Fedimint's Lightning Gateway architecture, from a CLN extension, to supporting LND, modularizing each component, implementing a new cryptographic contract protocol with the federation, and adding LDK-node support.

Awesome Payments: Social, AI and Stablecoins

New consumer technologies are quickly driving novel applications for advanced payments. As internet native money, Bitcoin should be well positioned to dominate payments for these new consumer experiences. But just Lightning is not enough, eCash is needed to drive Bitcoin payments adoption.

Blind Signatures & Anonymous Credentials

There are many ways of constructing e-cash systems out of cryptographic building blocks. This talk will overview some of those building blocks.

Basics of Cashu Wallet development with cashu-ts

This workshop is a live-coding session. We will be investigating the basics of Cashu web-wallet development, using the cashu-ts TypeScript library. During the workshop I will explain fundamental Cashu concepts and how they are applied in cashu-ts.

Ark & e-cash, enemies or frens?

The bitcoin payment protocol space is heating up. How do Ark and e-cash compare as alternatives for moving bitcoin around?

Building a Custodial Lightning Wallet the Right Way

Traditional Lightning wallets offer a stark choice: complex and non-custodial or privacy-compromising and custodial. Cashu bridges this gap, enabling developers to build user-friendly Lightning-enabled apps without the usual complexities. In this hands-on workshop, with the help of cashu-ts and Replit, participants will implement sending and receiving Lightning payments while exploring privacy features, offline capabilities, multi-currency support, and user-selectable custodians.

Hashpools: A Peer-to-peer Free Market for Bitcoin Mining

Mining bitcoin has come to rely almost exclusively on incumbent mining pools serving as trusted third parties to produce block templates and process payouts. While the system works well enough for most miners, it still suffers from the inherent weaknesses of the trust based model. Completely decentralized mining is not really possible, since mining pools cannot avoid bending the knee to the most well capitalized pool operator. The need for capital to smooth out mining reward variance increases pool centralization, limiting the minimum practical pool size and cutting off the possibility for small casual mining, and there is a broader cost in the loss of the ability to mine UTXOs that do not pass through custodial wallets. With the possibility of block withholding, the need for trust spreads. Mining pools must be wary of their hashers, hassling them for more information than they would otherwise need. A certain percentage of fraud on the part of the mining pool cartel is accepted as unavoidable. These costs and privacy violations can be avoided by mining to a solo pool, but no mechanism exists to buy hashrate directly without a trusted party. In this talk, I propose a solution to the mining pool centralization problem using a self-hostable FOSS mining pool stack to generate ecash assets backed by mining shares. The system is robust as long as some honest pool operators, anywhere in the world, are able to host it without interference from the state.

eCash is Obsolete: ZK is the Future

eCash systems were once revolutionary, but they now belong to a bygone era. As the Bitcoin economy grows, the limitations of these legacy systems become increasingly apparent. In this talk, discover why Zero-Knowledge (ZK) systems are the future, offering privacy, scalability, and decentralization. It’s time to move beyond eCash and embrace the next generation of technology.

Submarine Swaps

A talk about submarine swaps, liquidity, and lightning

Ecash: New Frontiers in Privacy

Ecash can improve privacy and connectivity. Is it worth the loss of control of custody?

Day 2 Closing

Hacking

Hacking

Hackathon Presentations

Hackathon Judging

Hackathon Awards + Closing