Write the key on chain (0 1 0)

The coin checks a signature against the key stored on chain. A key is 1,952 bytes; expanded for the verifier it is three code contracts, one transaction each. Anyone may write any part; a written part never changes.

The account (1 0 0)

Load a key, or read any lattice account by its id.

Waiting orders

Deposit

Coins go into the account by anyone's hand; they come out only by the key's order.

Orders

Your key signs an order here; the chain checks it. Any wallet can then relay it and pay the gas, about 3.6M. The order's nonce makes each signature good once.