01ONLINE
Load your value.
Deposit stablecoins on Ethereum to create a digital banknote. Its value is secured through a smart contract.
STABLECOIN VALUE. CASH FREEDOM.
Cash, without
the connection.
Money should move when you do.
Pay with stablecoins, directly between devices.
No internet needed at the moment of payment.
AndroidiOSWear OSWORKING PROTOTYPE
VALUE IN YOUR HANDS
NO SIGNAL.
STILL PAYING.
STILL PAYING.
Banknotes + coinsTwo ways to carry value
ACTUAL PROTOTYPE · PIXEL 7A · TEST WALLET
01 — THE PAYMENT FLOWONLINE AT THE EDGES. OFFLINE IN BETWEEN.
Load it. Pass it.
Cash it out.
Stablecoins become digital cash you can carry. Value moves from one device to another, and returns to Ethereum when it’s redeemed.
02OFFLINE
Pay, person to person.
Transfer value directly between nearby devices. Secure hardware prevents the same value from being spent twice.
03ONLINE
Redeem on Ethereum.
The holder returns online to redeem the value. Each user has their own smart contract, rather than one central payment contract.
Load and prepare value while connected. Once it’s offline-ready, payments can continue without an internet connection.
02 — A NEW KIND OF WALLETFAMILIAR FORM. DIGITAL POSSIBILITIES.
A little cash.
A lot of character.
A digital banknote can look like something worth keeping. Give it a custom face, a personal image, or even an animation.
01
Banknotes with personality
Distinct notes carry value and a face of your choosing. The artwork makes the experience yours.
02
Coins for the exact amount
Convert a banknote into fungible value in your coin purse. Pay flexible amounts, then redeem that value on-chain.
Shown here: illustrative banknote artwork from the prototype. Face artwork is independent of the stablecoin denomination.
INSIDE THE PROTOTYPEANIMATED FACE
100.00 USDCILLUSTRATIVE TEST VALUE
Carpați Cola · animated banknote
See the real app screens
03 — PRIVACY, BY CHOICETWO WAYS TO PASS THE SAME VALUE.
Your payment.
Your privacy.
Choose an anonymous payment chain, or move a banknote’s key directly between compatible secure elements.
ANONYMOUS PAYMENT CHAINPatent pendingThe journey is verified.
The journey is verified.
The parties are anonymous.
Each transfer adds to the banknote’s payment chain. On redemption, the user’s Ethereum smart contract sees that chain, while the parties remain anonymous.
The payment itself happens offline. The chain becomes visible on redemption.
PASSING A BANKNOTESTANDARD MODE
Holder ASecure hardware
Signed handoff
→
A new chain entryHolder BSecure hardware
Ethereum redemptionPayment chain presented to the user’s contract
ILLUSTRATED PROTOCOL FLOW
Deposit and redemption still happen on-chain in both modes. High privacy describes the secure-element handoff; it does not erase earlier chain entries.
04 — SECURE WHERE IT MATTERSTHE HARDWARE IS PART OF THE PAYMENT.
Spend it once.
That’s the point.
Offline cash needs more than a balance on a screen. HeisenCash uses secure hardware to enforce ownership and prevent double spending.
The security is already inside.
Uses the phone’s internal Trusted Execution Environment or secure element. No external secure element is needed on compatible Android devices.
Hardware capabilities determine the security level.Security that sticks with you.
An external NFC sticker provides the secure element for iPhone payments. Compatible stickers also enable the high-privacy banknote transfer mode.
High privacy requires compatible secure elements on both sides.Cash, a little closer.
The same offline payment idea, in a smartwatch experience. Carry and exchange value from your wrist with the Wear OS app.
Part of the cross-device working prototype.One contract for each user.
Ethereum handles redemption through individual user smart contracts. Offline payments move between devices without contacting a central payment contract.
05 — ALREADY TAKING SHAPEREAL SCREENS FROM THE WORKING PROTOTYPE.
From an idea
to in your hand.
A working prototype on Android, iOS, and Wear OS. Banknotes, a coin purse, and device security come together in one payment experience.
PROTOTYPE / EARLY ACCESSThese are actual prototype screens with test balances. Switch both phones between Home and Wallet, or select a screen to take a closer look.
A FEW GOOD QUESTIONSThe details
The details
that matter.
What does “offline” actually mean?
The payment between nearby devices does not need an internet connection. Depositing stablecoins, preparing offline-ready value, and redeeming on Ethereum require connectivity.
How is double spending prevented?
Ownership is controlled by secure hardware. On compatible Android devices, the internal TEE or secure element enforces single-use signing. On iOS, an external NFC sticker provides the secure element. The app’s security level reflects the hardware’s capabilities.
What does Ethereum see?
In standard mode, the payment chain is presented on redemption, with anonymous parties. In high-privacy mode, a banknote’s private key is transferred between compatible secure elements without adding a new transaction-history entry. Deposit and redemption remain on-chain.
What’s the difference between banknotes and coins?
Banknotes are individual pieces of digital cash with custom faces. A banknote can be converted into fungible value in the coin purse, making flexible payment amounts possible. That value can later be redeemed on-chain.
Can I download HeisenCash today?
HeisenCash is currently a working prototype / early-access project. This site introduces the payment model and demonstrates the experience; public download links are not available here yet.
Stablecoins,
out in the world.
For the moments between connections.
For value that moves person to person.