Bitcoin tools
for people who
verify.

Before any Bitcoin can move, Alice needs a wallet — and the safest kind is a hardware wallet, a small dedicated device whose only job is to keep one secret safe and sign things with it. Think of it as a tiny offline vault that fits in your hand. She unboxes it, plugs it in for the first time, and the device asks her to set it up.

Generating randomness from physics. Inside the device, a true random number generator pulls entropy from physical noise — tiny voltage fluctuations, hardware events — and produces a 256-bit random number. That randomness is then encoded as 24 simple English words from a fixed list of 2,048 (things like "apple", "mountain", "ocean"). This list is the seed phrase. Each word maps to 11 bits of the random number, with a checksum at the end to catch typos. The seed phrase IS the entire wallet — every key, every address, derived from these words.

Write it down. On paper. Never on a screen. The device shows the words one at a time on its small screen. Alice writes each one in order on the paper card that came in the box. She does NOT take a photo. She does NOT type it into her computer. She does NOT email it to herself. The whole point of a hardware wallet is that the seed only ever exists on the device and on her paper backup — never on any internet-connected machine where it could be stolen.

When she is done, she stores the paper somewhere safe — a fireproof safe, a safety deposit box, split across two locations. From now on, those 24 words ARE the bank account. Lose them = lose the Bitcoin. Anyone who finds them can take everything.

— The list of 2,048 words is standardized across every Bitcoin wallet (BIP-39). A seed generated on a Coldcard works in a Trezor, works in a phone wallet, works in any compliant software. The seed is the wallet — the device just safeguards and uses it.