ZoneBitcoin EditorialSince its inception, Bitcoin has been touted as "peer-to-peer electronic cash." However, in practice, most Bitcoin transactions are public, traceable, and bear little resemblance to the anonymous cash we use every day.
This is where comes in Cashu, an open-source protocol that brings the concept ofcash based on blind signatures developed by David Chaum. Cashu could well represent a new revolution in the Bitcoin universe.
Let's see how in this article.
What exactly is Cashu?
Cashu is a protocol that allows the creation of anonymous and instant electronic payment tokens, backed by Bitcoin.
It is based on 40-year-old technology: Chaumian blind signatures, invented by David Chaum in 1982.
The idea is simple but powerful: allow a user to own digital tokens, which they can transfer directly to another user, without anyone (even the issuer) knowing where the money comes from or to whom it goes.
To conclude:
- Cashu = Bitcoin + blind signatures + Lightning Network
How does Cashu work?
The system is based on two key players:
1️⃣ The Mint (the issuer)
It's a kind of "private bank" that receives your bitcoins (often via Lightning) and issues you blindly signed ecash tokens in exchange.
2️⃣ The Cashu Wallet (the user client)
This is your wallet, which contains your Cashu tokens. You can store them, send them to others, or convert them back to Bitcoin at any time via the mint.
The step-by-step process:
- You deposit sats with a mint.
- The mint issues you Cashu tokens, blindly signed.
- You then hold these tokens locally, like digital banknotes.
- You can then:
- Transfer them to other users (peer-to-peer)
- Convert them back to Bitcoin at any time.
All this without Mint being able to connect your initial deposit with your subsequent transactions. This is the power of blind signatures.
Why is this revolutionary for Bitcoin?
Bitcoin is decentralized and censorship-resistant. But privacy isn't its strong point. Every transaction is recorded on the blockchain, visible to all.
Cashu complements Bitcoin on this point:
- ✅ Complete confidentiality of transactions
- ✅ Instant and near-free transactions (off-chain)
- ✅ No public footprint
- ✅ Can work even in cash offline, by QR code, USB key, or even paper
In other words : Cashu restores Bitcoin to the function of true electronic cash.
Who is behind Cashu?
The project was initiated by a pseudonymous developer known as Street, in 2022. Cashu quickly resonated with the Bitcoin community, which has long been looking for viable cash solutions.
Today, Cashu's development is financially supported by the organization OpenCash Association, based in Switzerland.
OpenCash funds development, supports security audits, encourages protocol initiatives, and funds several full-time developers.
Can anyone deploy a mint?
Yes, and that's one of the key points of Cashu.
- ✅ The protocol is open-source.
- ✅ Anyone can deploy their own mint.
- ✅ There are multiple implementations (Python, Rust, Go, etc.).
- ✅ The ecosystem is beginning to diversify: we are seeing the emergence of public mints, private mints, and even community mints for certain communities Nostr.
On the other hand, unlike Bitcoin, mint requires trust : you have to trust that the mint will honor its commitments when you want to convert your tokens back to Bitcoin.
That's why the idea is to never store large sums there, but rather everyday amounts, as you would with cash in a wallet.
Who is it actually useful for?
Cashu opens up a wide range of use cases:
- Micropayments on the Internet : paywall, access to APIs, content monetization.
- Censorship-resistant messaging : anti-spam protection (e.g. via Nostr).
- Private payments for VPNs, sensitive content, independent press.
- Electronic cash for unbanked populations or in sensitive areas.
- Use in offline mode, in areas with low connectivity.
Concrete example :
You can send 500 sats to a friend with a simple QR code, without going through the blockchain or exposing your identity. Another example is a child who can buy donuts for 16 sats in a village in Burundi.
Limitations and precautions to know
- Counterparty risk on the mint : if the mint disappears, your tokens potentially become unusable.
- Recommended use: modest amounts, everyday use.
- Requires minimal trust in the mint operator.
This is why some people talk about "chains of mints" or multi-mint systems to spread risks.
The Future of Cash
Cashu is still in its infancy, but interest is growing:
- Possible integration with Nostr.
- Experiments with pay-per-second streaming.
- Application to AI to limit abuse (micro payments for API).
- Possibility of integration into physical commerce (digital cash POS).
Some even see Cashu as a model adaptable to future private electronic currencies, competing with state CBDCs.
Last word
Cashu is a return to its roots: pure digital cash. A simple, flexible, and efficient protocol that addresses one of Bitcoin's shortcomings without compromising its principles.
Bitcoin is the settlement and sovereignty layer.
Cashu becomes the layer of confidentiality and fluidity in everyday life.
For further :
- Official website: https://cashu.space
- Project support: https://opencash.dev
- Source code: GitHub Cashu
