Paper wallets — coins you can hold, and their weak spot

Coins you can see

A paper wallet is an address and a private key printed on paper. The front shows the address, safe to show anyone; under the scratch-off on the back is the private key that spends the coins. The coins are still on the ledger; the paper holds the key.

For Mobick, paper was more than storage. Wallets came inside a book, were handed out on mountains and abroad, and are still given at weddings, births and birthdays. The Mobick blog calls it a P2P culture outside exchanges that revives early bitcoiners’ habit of holding their own keys. If exchanges close, the paper remains.

Scratch one yourself

The wallet below was just created in this browser for practice. Flip it and rub the scratch area. When the key appears, “Sweep to app” unlocks.

BTCMobick PAPER WALLET

100 BMB

Address (public)—

Private key — do not scratch

—

↖ Rub with a finger or mouse to scratch

1Front: address
Anyone can check the balance from the address. It is safe to show.
2Back: scratch
Scratching reveals the private key. From now on, anyone who sees this paper can move the coins.
3Sweep
A wallet app reads the key and sends the whole balance to a new address of yours.
4Spent paper
Never reuse a swept paper wallet. Keep it only as a keepsake.

A practice paper wallet. Its key exists only in this browser and holds no real coins.

FIG. 1Practice paper wallet. The front QR is decorative and will not scan. The key disappears when you close the page.

Sweep: from paper to app

Sweeping means letting a wallet app read the paper’s private key and sending its entire balance to a new address of yours. The official docs recommend it for any airdropped paper wallet: choose “import paper wallet” in the app and scan the WIF key or QR.

After sweeping, never reuse that paper wallet. Its key is exposed; anything sent there can be taken.

The weak spot

Paper is an object, and whoever holds an object can do anything to it. In the 4 October 2025 live stream Oh Taemin showed what he found when he cut into an early 2023 airdrop wallet: four layers. Peel the first slightly and the private key showed through without scratching, and the layer could be stuck back unnoticed. Press “Peel the layers” above to see the structure.

Wallets made later by Mobickers Inc. use different paper and do not peel so easily, but there may be other ways nobody has thought of. It comes down to cost: the more one sheet holds, the more someone will spend to open it secretly — the same logic as keeping no more than about a million won on a phone.

EVM paper wallets too

In the same stream Oh said future airdrops would be EVM-based. The 10-Mo Miracle (Harvest MOVN) indeed uses EVM paper wallets printed with a BSC address. Only the chain differs: the front is the address, the back the key, and a scratched sheet is an opened envelope. The 10-Mo lesson covers it.

Where to buy

Blank paper wallets (no coins on them) are sold on Coupang. It is not Mobicus selling directly but a wholesale reseller.

When it arrives:

Check for scratch marks or signs a layer was peeled. If in doubt, do not use it.
Start with a small amount and try a sweep before relying on it.
Oh Tae-min says getting it directly beats something that passed through other hands (members stream, 29 Mar 2025). It is still a key someone else printed, so keep large amounts on a key you made yourself.

Buy hardware wallets only from the maker’s official site. Open marketplaces, second-hand and proxy purchases can be opened or swapped in transit. On arrival, check the seal and run the maker’s genuineness check. If the box already contains a written recovery phrase, do not use that device.

Device	Official site
Coldcard	coldcard.com (store: store.coinkite.com)
Trezor	trezor.io
Ledger	ledger.com
BitBox	bitbox.swiss
Keystone	keyst.one
Jade	blockstream.com/jade

Back up first

Devices and paper get lost. What you must protect is the recovery phrase. If a hardware wallet breaks or disappears, the phrase restores it on a new device. Without the phrase, a working device is no help. A paper wallet is its own only copy, so sweep it into a wallet you have backed up.

When backing up:

Write it by hand on paper. No photos, screenshots, cloud, messengers or note apps.
Write the numbers and order clearly, then check against the screen once more. One wrong word or order and it will not restore.
Keep copies in two different places. Some people stamp it on a metal plate against fire and water.
Do not split the words in halves. If one half leaks, the rest becomes far easier to guess.
If you used a passphrase, back that up separately too. Without it, the phrase alone will not open the wallet.
Never type or tell the phrase to any website, app or person. Anyone asking for it, “support” or “the manufacturer”, is a scam.
Practise a restore with a small amount first, then add larger sums.

How to make and keep a recovery phrase safe — broken randomness, offline generation, crossing borders — is in Keeping your seed safe.

Summary

Front: address (public). Back: private key (secret). Coins live on the ledger.
Sweep to an app on receipt; never reuse a swept paper wallet.
Early paper wallets could be peeled and re-stuck. Paper that changed hands is compromised.
Loaded paper wallets are not things to buy and sell.