In case your machine connects to the web in any respect, it needs to be thought of probably compromised. Think about what occurs to it should you go to GMail, which occurs to ship an advert with compromised JavaScript, for example.
Safe storage of a bitcoin pockets can solely be actually thought of “principally safe” if the machine is rarely linked to any community, and solely you’ve gotten bodily entry to it. Ensure that all connectivity to the machine is disabled, resembling USB, serial ports, WiFi, and so on.
Sending a transaction over the bitcoin community for an offline, or chilly pockets, consists of producing the transaction offline, then manually copying the transaction’s hex illustration to a node that is linked, and having it broadcast the transaction. That’s basically what the Trezor and Ledger {hardware} wallets do – they generate the transaction internally in such a means that your personal key by no means leaves the confines of the {hardware} pockets. It then sends solely the ensuing transaction particulars to the bitcoin community, with the signature together with your public key which proves you signed it with the corresponding personal key.
Search “bitcoin chilly storage” if you wish to go down the rabbit gap.