Cashu is Ecash for Bitcoin

Cashu is a free and open-source Chaumian ecash system built for Bitcoin. Cashu offers near-perfect privacy for users of custodial Bitcoin applications. Nobody needs to knows who you are, how much funds you have, and with whom you transact.

What is Cashu?

Cashu is a new ecash protocol for custodial Bitcoin applications that is tightly integrated into the Lightning network. An Ecash system consists of two parts, the mint and the ecash wallet. Ecash transactions are untraceable, instant, and require no fees. Cashu is built for Bitcoin. Wallets use the mint's Lightning node for making or receiving Bitcoin payments in exchange for ecash. A Cashu mint does not know who you are, what your balance is, or who you're transacting with. Users of a mint can exchange ecash privately without anyone being able to know who the involved parties are. Bitcoin payments are executed without anyone able to censor specific users.

Cryptography

Cashu is an Ecash implementation based on David Wagner's variant of Chaumian blinding (protocol specs) which was later written and discussed in this thread.

Protocol

Cashu NUTs (Notation, Usage, and Terminology) are Cashu's protocol specifications and the developer libraries make it easy to write wallets and mints.

Apps

There are various ways to use the Cashu protocol. It's available as a command-line tool (CLI) or with a graphical user interface using Progressive Web Apps (PWAs) or native mobile apps.

Libraries

Cashu libraries are available for Python, Golang, TypeScript, and JavaScript. Click here to see the full list. Here are some examples:

Join the Cashu R&D group

We have a channel on Telegram focussed on Cashu R&D. If you're developer and would like to start working with Cashu, please join us here.

This website

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