Glossary / Wallets & custody
Paper wallet
- Definition
- A paper wallet is a printed private key and address from the pre-hardware era, and spending from one safely is harder than the format ever admitted.
A paper wallet holds exactly one key pair, generated in a browser and printed onto a sheet, with no software attached to it. The format peaked between 2011 and 2014, before signing devices were affordable and before deterministic backups became standard. Anyone still holding one should move the coins into a modern wallet rather than trust a decade-old printout.
How it works
Status: no maintained wallet produces paper wallets today. The practice faded after BIP-39 recovery phrases were proposed in September 2013 and cheap signing devices followed, and the accepted replacement is a recovery phrase stamped in metal behind a hardware wallet.
A generator such as bitaddress.org, first published in 2011, ran entirely inside the browser tab. It gathered entropy from mouse movement, produced one private key, derived the matching address, and drew both as text and as QR codes on a page laid out for printing. You printed the sheet, closed the tab, and paid the address. Nothing was registered anywhere: the address only becomes visible to the world when a transaction pays it.
Four things went wrong in practice, and none of them are cryptographic.
The secret passes through a general purpose computer and a printer. Page caches, print spoolers, and the internal storage in office printers all keep what they were asked to render, so an attacker who reaches either machine reaches the key.
Print is fragile. Inkjet ink runs when wet, thermal receipt paper fades toward blank within a few years, and a QR code with a crease through it is a key you can no longer scan.
Spending was the real killer. One key means one place to hold value, so a partial spend needs somewhere to send change. Software that imported the key instead of sweeping it paid the change to an address the paper knew nothing about, and owners who filed the sheet away and wiped the software lost the remainder.
Privacy went with it. One key means one address, so every payment you ever received landed on the same public identifier, and anyone who learned it could read your entire balance history. Deterministic wallets fixed that by handing out a fresh address per payment, which a printed sheet cannot do.
Where you see it
Paper wallets surface in inheritances, safe deposit boxes, and gifts made around 2013, alongside Casascius physical coins, whose maker stopped embedding private keys in late 2013 after FinCEN told him the practice made him a money transmitter.
If one reaches you, sweep it rather than import it. Sweeping builds a single transaction that moves the whole balance into a wallet you control, which ends the change problem outright. Look up the address on a block explorer first, using only the public side, so you know what is there before any secret is typed. Then treat the sheet as public from the moment the key touches a keyboard or a camera, because you cannot know what else saw it.
Paper wallet vs cold storage
A paper wallet is one storage format; cold storage is the property of a key never meeting an internet-connected device. The two get equated because paper feels offline, yet a key created in a browser and rendered by a printer has already been handled by two networked machines before the ink dries. A hardware wallet generates its secret inside a chip with no interface for exporting it, which is what the offline claim was always supposed to mean.