Wallets & Security
The computer prepares. The device decides.
A hardware wallet is a small device with a big promise: your keys never leave it. Even if your computer is compromised, the device only signs what you confirm on its own screen. It removes one class of risk — not all of them.
The problem
Malware on your computer swaps the recipient while you send.
You copied the right address. You checked it. Press Send and read your computer carefully — then read the little screen on the device.
One payment, two screens
NOTHING SIGNED YETYour computer
Ready to send. Press Send.
The device's own display
You haven't looked at it yet.
Nothing has been signed. Press Send to start.
The two addresses shown above are invented stand-ins for this lesson — they are not real addresses, and the amount is illustrative.
Nothing left the device, so nothing moved. Look at why that was possible. Every surface in that chain was running on a machine you can no longer trust — the window, the copied text, the confirmation dialog, all of it. Except one. The compromised computer cannot write to the device's little screen. That screen is driven by the device itself, and it shows the transaction the device is actually about to sign. In a chain where everything else can be rewritten, it is the one surface still telling you the truth.
That is the whole reason verify on the device, every time is a habit and not a suggestion. The check only protects you on the occasion you actually perform it — and you cannot know in advance which send that will be. An antivirus program is sensible but it is not proof, and confirming quickly to "beat" anything is the opposite of security. If what the device shows does not match what you meant, you abort, and nothing is signed.
The definition
Three claims — one of them is a myth.
Tap each card for what is actually true underneath.
Hands on
Six steps. Watch where the private key is.
The full signing sequence, one state at a time. At every single step, check the two readouts: where the key sits, and what actually crosses the cable.
Times the private key crossed the cable: 0 — of 6 steps. The computer prepares; the device decides.
The bridge
Three habits, and one honest limit.
A hardware wallet only delivers its protection with clean habits around it.
That closes the set. Hot: online, practical, a small amount for daily use. Cold: keys offline, the principle for long-term holdings. Hardware: cold yet usable — it signs inside the device, the display verifies, and the seed stays the backup. You can now pick the right tool for a situation. What is left is the part no device fixes: the mistakes people actually make with their own wallets, which the next lesson takes apart one at a time.
Check yourself
Five questions.
Answers come straight from this lesson. Submitting completes it.