How it works
A sealed vault you can hand to anyone.
On every chain, coins are bound to keys, so changing who owns them means moving them. On NEAR, a contract can control native addresses on other chains. Bearer turns that into a vault you can hand over in one NEAR transaction, with a seal that stops anyone before you from keeping a way back in.
01 · Overview
A vault is an NFT that controls three addresses.
Each vault is a token on NEAR. The Bearer contract derives a Bitcoin, a Base and a Solana address for it through NEAR Chain Signatures. Only the contract can ask NEAR's MPC network to sign for those addresses, and it only does so for the vault's current owner.
You
the vault's owner, on NEAR
Bearer contract
bearer.testnet
NEAR MPC network
v1.signer-prod.testnet
02 · The one rule
It can change hands only while it's sealed.
A vault can change hands only while it is sealed. Breaking the seal is the only way to get a signature, and it can never be undone.
The risk with handing over a wallet is a signed transaction kept in a drawer: a previous owner could broadcast it later and empty it. Bearer removes the drawer. While a vault is sealed, the contract can't request a signature for it. Once its owner breaks the seal, no transfer path will accept it.
| Property | Sealed | Opened |
|---|---|---|
| Can receive deposits | Yes | Yes, still withdrawable by the owner |
| Can change hands (any path) | Yes | Never |
| Can request a withdrawal signature | Never | Yes, by the owner, any number of times |
| Signatures ever requested | Always 0 | 0 or more |
| How it gets here | create_vault | break_seal by the owner |
Start
create_vault
Three addresses, derived by the contract
Sealed
Can change hands
0 signatures ever requested
Transfer: new owner, still sealed
Opened
Withdrawals only
Owner fixed forever
Withdraw, as often as you like
03 · Handing it over
One NEAR transaction. Nothing moves on the other chains.
Send a sealed vault to any NEAR account. The contract checks the seal and changes the owner in one transaction. The coins stay exactly where they are, at the same addresses.
Changing hands
Control of the three addresses and everything at them, and the right to break the seal.
Not changing
No coins move. The addresses and the public history stay the same.
After this, you can't
Break the seal, withdraw, or take it back.
- Every transfer path goes through one gate in the contract, and that gate refuses opened vaults.
- The custody log on the back of the vault gains a line with the new holder and the date.
- The former owner sees that they no longer hold it, and the contract rejects anything they try.
04 · Breaking the seal
Open it to withdraw. After that, it stays yours.
To take coins out, the owner breaks the seal. The app sends it in the same NEAR transaction as the first withdrawal, so if the withdrawal is invalid, the seal stays intact. NEAR's MPC network then signs a transaction the contract built itself, paying the address the owner chose.
- This can't be undone. An opened vault can never be transferred again.
- You can withdraw what's inside now or later, as many times as you like.
- Coins sent to an opened vault stay withdrawable by its owner.
Sealed
Unopened. No signature has ever been requested for this vault.
Opened
Its owner broke the seal. It can't change hands.
Signed and sent
Each withdrawal shows its status and explorer link until confirmed.
05 · Why retries are safe
Every signature pays the same owner.
Once a vault is opened, its owner is fixed forever. Every signature the contract requests for it is for a withdrawal that owner asked for, paying where they chose. That makes the awkward cases simple.
A request times out
Try again. If both signatures turn up, they spend the same coins or the same nonce, so the chain accepts at most one.
Fees need a bump
That's just another withdrawal at a higher fee, from the same owner.
Partial withdrawals
Fine. A vault that can never move has no “what's left inside” question to answer.
06 · What you're trusting
No bridge, no custodian key. Here's what's left.
NEAR's MPC network
A threshold of independent operators must agree to sign. Bearer uses v1.signer-prod.testnet.
The Bearer contract
Open source and locked at bearer.testnet. Its code hash matches a reproducible build.
Each chain's own rules
A withdrawal confirms when Bitcoin, Base or Solana accepts it, with that chain's fees and finality.
Display data
Balances come from public explorers and RPCs, each named with the time it was checked. The contract never relies on them.
07 · Limitations
What this version doesn't do.
- Once opened, a vault is spent as a hand-over: it can't be sealed again or transferred.
- Bearer doesn't escrow payments between people. It guarantees what you receive, not that someone pays you.
- Native coins only: BTC, ETH on Base Sepolia and SOL. No tokens, no other EVM networks.
- Balances are observed data and can lag an explorer by a few seconds.
08 · FAQ
Questions people ask.
Is this real money?
No. Bearer is a testnet prototype: NEAR testnet, Bitcoin testnet4, Base Sepolia and Solana devnet. Testnet coins have no value. Dollar figures are estimates, labelled est.
What stops the old owner from keeping a signed withdrawal?
There's nothing to keep. A sealed vault can't request a signature at all, and a vault can only change hands while sealed. So when you receive one, no withdrawal signature has ever existed for it, on any chain.
Can I seal a vault again after opening it?
No. Breaking the seal is one-way. An opened vault keeps working for its owner, who can withdraw from it as many times as they like, but it can never be handed on.
Can the Bearer team move my coins?
No. The contract is locked: it has no full-access keys and no upgrade or admin methods, so nobody can change its rules or ask it to sign anything outside its typed withdrawal methods.
Does Bearer handle payment if I sell a vault?
No. Bearer guarantees that what you receive is sealed and yours. It doesn't escrow payments between people, so agree on payment the way you would for anything else handed over in person.
Why only Base Sepolia for ETH?
The vault's 0x address exists on every EVM network, but this version only signs withdrawals on Base Sepolia. Funds sent on other networks can't be withdrawn by this version.
What if I lose the account that holds a vault?
Then the vault is lost, like cash. Bearer can't recover vaults for anyone.