Glossary

Short definitions of the words used in AirWallet and these docs, from air-gapped and watch-only to PSBT, PCZT, key images and view keys.

Air-gapped: kept away from every network. AirWallet's offline signer is air-gapped: it never connects, and the only thing that goes to it or comes from it is a QR code, read by a camera.

AirWallet Offline: the hardened build that can't connect at all. On Android it has no internet permission. On a computer, the operating system blocks its network. As a Chrome extension, it has no network permissions.

Animated QR code: a code too long for one QR code, shown as a series of frames. The scanner can read the frames in any order, and a frame it misses is made up by later ones. AirWallet's own animated codes start with AF1:.

Approval (token approval): on Ethereum and the other EVM networks, permission you give a contract to spend one of your tokens, or to move all your NFTs in a collection. Approvals are often unlimited, and they stay until you remove them. See Notifications and token approvals.

Argon2id: a way of turning a password or PIN into an encryption key that's deliberately slow and uses a lot of memory, so guessing passwords takes a long time. AirWallet uses it for the app lock, backup files and AirWallet Online's password.

BC-UR: a standard way of putting data into QR codes, including animated ones. These codes start with ur:. Sparrow, MetaMask, Keystone and other apps use them, and AirWallet reads and writes them, so its offline signer can sign for those apps.

Birthday (restore height): the date, or block number, a Monero or Zcash wallet starts scanning the blockchain from. Coins received before it don't show. Other wallets ask for it when you restore your words there, and AirWallet's Export private key shows it.

Duress PIN: a second PIN that opens a separate AirWallet holding only the wallets you picked for it, for when someone forces you to open the app. See App lock, duress PINs and disguises.

Everyday wallet: the mode for a phone or computer you use online. It watches balances, prepares payments as QR codes and sends what the offline signer signed. It can also hold keys of its own, like any ordinary wallet.

EVM networks: networks that run Ethereum's software. AirWallet supports Ethereum, Base, Arbitrum, Optimism, Polygon, BNB Chain, Avalanche and Robinhood Chain. One Ethereum address works on all of them.

Fee and gas: the fee pays the network to include your transaction. On Ethereum and the other EVM networks, the fee is the work the transaction takes (its gas) times the price of each unit. AirWallet asks the network for both, and the review shows a likely fee and the most it could be. On every chain, AirWallet warns you about a fee that looks too high.

Key image: a value that every spent Monero coin publishes, made with the wallet's spend key. A watched Monero wallet can't make key images, so it can't tell which coins have been spent until the offline device sends them. That's why the first payment from a watched Monero wallet takes an extra round.

Multisig: a wallet that needs signatures from several keys to spend, for example 2 of 3. AirWallet's offline signer can be one of the signers: for Bitcoin multisig coordinated in apps like Sparrow, for a Safe on Ethereum networks and for Squads on Solana.

Nonce: on Ethereum, a transaction's number. Each transaction from an address carries the next number, and the network accepts each number only once. That's how a stuck payment can be replaced or called off. On Solana, a durable nonce lets a transaction signed offline stay valid until it's used, instead of expiring within about a minute.

Offline signer: the mode for a device that never goes online again. It keeps the keys, shows exactly what each payment does, signs it, and shows the signature back as a QR code.

Passphrase: an optional extra word or phrase (sometimes called a "25th word") set together with a recovery phrase. Each passphrase opens a different wallet, so you need the exact same one to restore.

PCZT: a partly created Zcash transaction (ZIP 374): Zcash's format for a transaction made on one device and signed on another. Your everyday wallet builds it and makes the proofs. The offline signer checks every output against its own keys, shows the payment, and adds its signatures.

Polyseed: a 16-word Monero recovery phrase that also records the month the wallet was made. Feather, Cake Wallet and ANON use it. A Polyseed wallet holds Monero only.

PSBT: a partially signed Bitcoin transaction (BIP 174): Bitcoin's standard format for passing a transaction to a signer and back. AirWallet uses PSBTs between its two devices and with apps like Sparrow.

Recovery phrase: the 12 or 24 words (BIP-39) that make up a wallet. They restore its keys on every chain AirWallet supports, in AirWallet or in other wallets. Whoever has them has the money. See Backups and recovery.

Shielded and transparent: the two kinds of Zcash address. Shielded addresses (u1…, called unified addresses) keep the amount, the sender and the memo encrypted on the blockchain. Transparent addresses (t1…) are public, like Bitcoin's. Transparent ZEC has to be shielded before it can be spent.

Single-key wallet: a wallet with one private key for one chain, such as a vanity find or a key you imported. No recovery phrase covers it, so it needs its own backup.

Split key (vanity by someone else): a way to have someone else search for a Bitcoin or Ethereum vanity address without ever learning its key. Your wallet keeps a secret half, and only it can turn their find into a key. See Vanity addresses.

Subaddress: an extra Monero receiving address of the same wallet, starting with 8. If you give each payer a different one, nobody can link their payments together by address. All of them arrive in the same wallet.

Taproot and SegWit: two kinds of Bitcoin address. Taproot addresses start with bc1p and are AirWallet's default. SegWit addresses start with bc1q, for senders that can't pay Taproot. A recovery-phrase wallet has both, and AirWallet spends coins on either.

Vanity address: an ordinary address that contains a word you chose, found by trying keys until one matches. See Vanity addresses.

View key: a Monero wallet's private view key. With it, a wallet can see payments arriving and their amounts, but it can't spend them or see what's been spent. If it leaks, you lose privacy, never coins.

Viewing key: a Zcash wallet's viewing key (uview1…). It sees everything the wallet receives and sends, including amounts, addresses and memos, and it can't spend any of it.

Watch-only: a wallet the app follows without its keys. A watch-only wallet shows balances and history and prepares payments, but your offline signer has to sign them. The code from Show to my online wallet holds the wallet's addresses and no keys. For a recovery-phrase wallet, it also holds the Monero view key and the Zcash viewing key, so the everyday wallet can show those balances.