What is a paper wallet in crypto and is it safe?

A paper wallet is a piece of paper with a crypto private key and its public address printed on it, often as QR codes. Because the key never sits on an internet-connected device once printed, it was used as a simple form of cold storage. Today it is widely seen as an outdated method with risks that newer tools avoid.

What is a paper wallet in Bitcoin?

In Bitcoin, a paper wallet holds one private key and one address. You send coins to the address, and anyone holding the key can spend them. The Bitcoin Wiki says paper wallets were popular from about 2011 to 2016 and were nearly always made by websites that generated the key in a browser.

Modern wallets work differently. They use a seed phrase of 12 or 24 words that can create many keys and a fresh address for each payment. Our guide to hot wallets and cold wallets compares today's storage options.

Is a paper wallet safe?

The Bitcoin Wiki now calls paper wallets an obsolete and unsafe way to store bitcoin. Its main concerns are these:

• Printing: printers can keep copies in internal memory, shared printers may be logged, and wireless printers could expose data nearby.
• Address reuse: a single address encourages reuse, which harms privacy.
• Damage: one wrong character makes a printed key invalid, and water, folds or creases can ruin a QR code.
• No balance view: a sheet of paper cannot show a balance, so users rely on third-party block explorers.

Generator websites are another risk. In February 2021, CoinDesk reported research alleging that one site, BitcoinPaperWallet.com, created keys from a hidden set of test keys in its code. Researchers linked at least 124.85 BTC in losses to the issue. The site's owner denied it. If the generator knows your key, so can someone else.

How do you redeem a paper wallet?

The key step is to move everything at once. The Bitcoin Wiki explains why. If you import a paper wallet key and spend only part of the balance, the rest goes to a change address controlled by the software, not back to the paper. Users have lost funds by assuming the remainder was still on paper, or by destroying the paper after importing a key that was never part of the wallet's seed.

Sweeping avoids this. A wallet that supports sweeping reads the private key and sends the entire balance to a new address in your current wallet, after a network fee. The Bitcoin Wiki describes sweeping as the best option. Casa's support guide shows a more cautious method, signing the sweep on an offline computer so the key never touches an internet-connected machine. Once swept, the old paper key should be treated as used and not funded again.