Public & Private Keys Explained
📖 5 min read
Quick Answer
Bitcoin replaces usernames and passwords with a pair of keys. One you can share with the whole world, the other you must guard with your life. Together they let you receive money publicly and spend it privately, with no bank in between.
💡 Think of it as…
A glass mailbox on the street. Anyone can see inside and drop a letter through the slot (your public address), but only you hold the key that opens the door to take letters out (your private key). Everyone can pay you; only you can spend.
Private key: your secret
A private key is a randomly generated secret number. It proves ownership and is used to "sign" transactions. Whoever holds the private key controls the coins — which is why losing it means losing access, and leaking it means losing funds.
Public key & address: your handle
Your public key (and the address derived from it) is shared freely so others can send you Bitcoin. Crucially, the public key can be calculated from the private key, but never the other way around — thanks to one-way cryptography.
Digital signatures
When you spend, your wallet uses the private key to create a signature that anyone can verify with your public key — proving you authorized the payment without ever revealing the secret. No signature, no spend.
🔑 Key takeaway
Public key = receive (share it). Private key = spend (protect it). The math lets the network verify your payments without ever seeing your secret.
Why this matters for you
This is why self-custody matters: a hardware wallet keeps your private keys offline and in your hands, beyond the reach of exchange hacks, frozen accounts, or capital controls — a real concern for savers across Asia.
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What is a seed phrase then?▼
A seed phrase (12 or 24 words) is a human-readable backup that can regenerate all your private keys. Guard it like the keys themselves — anyone with your seed phrase controls your Bitcoin.
If my address is public, is my balance public too?▼
Yes — anyone can look up an address’s balance and history on the public ledger. That is why privacy-conscious users avoid reusing addresses.
What happens if I lose my private key?▼
The coins are permanently frozen on the blockchain — no one can recover them, including you. This is the trade-off of being your own bank, and why backups matter.