Payment links
Pay anyone with a link, even someone who has never used voidcash. Whoever opens it claims the HYPE, privately or to any address, without HYPE of their own.
A payment link holds HYPE that whoever opens the link can claim. The person you pay does not need a registered privacy key, or any HYPE for gas: they open the link, and the HYPE lands in their own private balance, or at any address they choose.
A link works like cash in an envelope, which is why the app draws it as a bearer note. Anyone who has it can claim it, once. Until then, you can take it back.
Payment links carry HYPE only. To pay a token such as VOID privately, send it to an address.
How it works
The link carries a private key, made in your browser. The app derives privacy keys from it, exactly as it derives
yours from your wallet's signature, and pays the amount privately to those keys. The key sits after the #:
https://voidcash.io/claim#k3J9xQ…Browsers never send the part after the # to a server, so opening the link does not reveal the key to the site.
Whoever claims uses that key to spend the note, from their own browser.
Create a link
Choose As a link
Open Send and choose As a link instead of To an address. Type the amount in HYPE and press Create link. The link form has no asset button; it says "Payment links carry HYPE only. Send tokens to an address."
Confirm in your wallet
The first time in a session, your wallet signs a message that opens your payment links (see Keep links safe). It costs nothing. Then, as for any private send, your wallet signs a Spend request and your browser builds the proof. The gas comes from your notes.
Share it
The app shows the note with the amount, the link, Copy link and, where the device has one, Share. Tap the note to turn it over: its back is the link's QR code, to show to someone in person. Send the link to the person you are paying, in a private message.
A link must hold more than twice the current gas estimate, because its claim pays its own gas out of the link.
The preview
Chat apps that show a preview of the link show You've been sent HYPE and Claim it privately, or to any address. No HYPE of your own needed., with a picture of the note whose amount is blurred. The server that serves the preview never receives the key, so it cannot know the amount.
Claim a link
Opening the link shows the note and the amount it holds. The person you paid then picks one of two ways.
| Claim privately | Claim to an address | |
|---|---|---|
| What they need | A wallet, to sign the activation message (twice while their address has no registered key) | Nothing: no wallet, no signature |
| Where the HYPE goes | A private note only they can read | The address they type, as public HYPE |
| What they receive | The link's amount less the gas | The link's amount less the gas, less the 1% exit fee |
| What the chain shows | A private transaction | An exit: the address and the amount |
| HYPE needed | None | None |
Both ways pay the gas out of the link. A claim to an address is an unshield: it pays the exit fee and, above the large-exit threshold, waits 24 hours.
A private claim does not register the claimer's key, so it needs no transaction from their wallet. Their wallet works all the same: they can hold, send and unshield the HYPE, since private actions pay their gas from the notes. The wallet shows Others cannot send to you privately yet with a Register my privacy key button until they register, which takes one small transaction paid in HYPE from their address.
What each side sees
| Who | Sees |
|---|---|
| You | A Payment link entry in your history, with the amount and the gas. Open link asks for the links signature once per session; then the entry shows Claimed or Not claimed yet, Copy link copies it again, on any device, and Status opens the link's page. |
| The claimer | The amount, before claiming. After a private claim, the HYPE in their balance. Nothing says who sent it. |
| Everyone else | A private transaction for the link, and one for a private claim. Not the sender, the claimer or the amount. A claim to an address is public: the address and the amount. |
After a private claim, the link's page shows This link was already claimed, and nothing about who claimed it: the claimer's note is encrypted to their own keys, which the link's key cannot read.
Take a link back
Press Status under the link in your history. While the link is unclaimed, claim it privately yourself: the HYPE returns to your notes, less the gas.
Keep links safe
- Anyone with the link can claim it. Send it only to the person you are paying. The app you send it through keeps the message, so prefer an end-to-end encrypted one.
- Your links open with a signature of their own. A link's key is derived from a second message your wallet signs ("Open your payment links on the voidcash vault…") and from a random nonce written, encrypted, into the change note of the transaction that paid it. Your history can rebuild the link on any device, with the same wallet. The activation signature alone shows that a link exists and what it holds, but cannot open it. Whoever obtains both signatures could claim your unclaimed links, so sign them only on the official app.
- A claimed link is spent. It cannot be claimed twice.
What can go wrong
| Message or symptom | What it means |
|---|---|
| "A link must hold more than twice the gas its claim pays." | Raise the amount. |
| This link holds nothing yet | The link's payment is not on the chain yet, or the link was never paid. Wait a moment and press Check again. |
| This link was already claimed | Someone with the link claimed it, or you took it back. |
| This is not a complete link | Part of the link was cut off. Open it exactly as it was sent. |
| "This link holds less than the gas to claim it." | Claiming would cost more than the link holds. |
| "This wallet does not open this link: it was made with another wallet, or the wallet signed differently." | Under Open link: the links signature does not match the link. Use the wallet that made it. |
| Could not read this link | The app could not read the chain. Press Try again. |
A payment link is a bearer note. Whoever sees it first can claim it, and nobody can reverse a claim.
Send privately
Pay another voidcash user from your private balance. Only the recipient learns the amount, and your address never appears in the transaction.
Private address
A link anyone can pay you with, which does not say who you are. Payers use HYPE from their wallet or their private balance; you move the payments into your balance.