QUICK INFO:

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• Watch-only wallets (WO): are wallets without private keys. Therefore, they cannot sign transactions. However, unlike cold storage wallets, they can (actually they must) be connected to the Internet. If the computer has malware, your privacy can be compromised, but not your security (again, watch-only wallets don't have the seed nor the private keys). In order to protect also privacy, it is better to use them in a secure computer using Tails OS (but not a cold computer obviously). They are useful to check the wallet activity and balance in real time, and for air-gapped transactions (see later).

• Setup: "Applications" > "Internet" > "Electrum Bitcoin Wallet" > provide name of wallet > "Next" > here choose the kind of wallet: "Standard wallet" if the related cold wallet (with private keys) is a standard wallet, or "Multi-signature wallet" if the related cold wallet is a Multisig wallet (here we'll assume a Multisig wallet) > "Next" > choose Multisig configuration of the relative cold wallet (here 2/3) > "Next" > "Use a master key" > "Next" > paste (e.g. from KeePassXC) the first Master Public Key (MPK), e.g. of wallet A > "Next" > the following message confirms that this is now the watch-only wallet "A" > "Next" > "Next" > paste the second MPK, e.g. of wallet B > "Next" > "Next" > paste the third MPK: C [please note: this is why in the previous video each KeePassXC database (e.g. "Computer A") needed to have the MPKs of all other wallets as well: in this way, every cold wallet (A, B, C) can control online the status of the wallet and do air-gapped transactions] > "Next" > provide password (e.g. create password in KeePassXC and paste it) > "Next" > done: now the wallet will connect to a node and synchronize.

• Please note: here we'll assume that we have already setup our own node, or a connection to a trusted node. However, this must be done before we connect our watch-only wallet to the Internet (see later, chapter 5). If you still haven't configured a connection to your node, create a watch-only wallet in the cold computer and save it on a USB: copy it to a hot computer only after you have configured a connection to your node (or, if you don't have it, to a trusted node).