Paper Wallet

A paper wallet is a private key, or the seed from which keys are derived, written or printed on a physical medium and kept offline. As an idea it predates modern hardware wallets and was a reasonable answer to a real problem: material that never touches a networked computer cannot be read by malware on one. Its weaknesses are practical rather than cryptographic. Whatever generated and printed it saw the key; printers keep spooled copies; paper burns, fades and is read by anyone who opens the drawer; and there is no PIN, no passphrase and no second factor between finding it and spending it. The larger flaw is in spending: using a paper wallet generally means importing the key into software, at which point it is a hot key on a live machine and the offline property is gone for good, even if only part of the balance was meant to move. Where the paper instead holds a recovery phrase for a wallet that signs on a separate device, none of that applies — the distinction is whether the key is ever typed into something connected.