Keys and wallets — your coins are not in your wallet

Wallets do not hold coins

Deleting your banking app does not delete your savings, and deleting your Mobick wallet app does not delete your BMB. Coins were never on your phone. They sit on the ledger, which says: “this amount can be spent only by whoever can open this address’s lock.”

So a wallet holds the key that opens the lock — the private key. Whoever holds the key is the owner. Lose it and nobody can open it for you. There is no password reset.

From private key to address

A private key is one huge random number — one of 2^256 possibilities, so no two people will ever collide by chance. From it comes a public key, and from that an address. Draw a new key below.

Draw a new private key

Practice only. Never send coins to a key made on this page.

1. 1Private key

   A random 256-bit number. Whoever knows it owns the coins.

   — →← ✕
2. 2Public key

   Private key × a point on the elliptic curve. Easy to multiply, impossible to divide back.

   — →← ✕
3. 3Public-key hash

   SHA-256, then RIPEMD-160 — 20 bytes.

   — →← ✕
4. 4Address

   A friendly wrapper. Mobick uses the same bc1… / 1… formats as Bitcoin.

   — —

The arrows only point one way. You cannot get from an address back to the public key, or from a public key back to the private key — so share addresses freely and never share private keys.

Every step is one-way. Multiplying the private key by a point on the elliptic curve is easy; going back from the public key is not. The address is a hash of the public key, so that is one-way too. Share addresses freely; never share private keys.

Signatures: proving ownership without showing the key

To send coins you publish a transaction: “send this address’s coins to that address.” How do you prove you made it? Showing the private key would hand it away.

The answer is a digital signature. Sign the transaction with the private key and anyone can check it with the public key. The key never leaves. Make a signature below, then tamper with it in transit.

① Me — sign with my private key

Message Sign

Private key—

message + signature

② Anyone — verify with the public key

Received message

Signature—

Public key—

Tamper in transit Change amount to 5 Change the recipient Verify with someone else's key

You can also edit the received message yourself. The signature is bound to the whole message — change a single space and verification fails. Making a signature needs the private key; checking it needs only the public key.

Change the amount or the recipient and the signature fails immediately; it is bound to the whole message. Nodes check every transaction’s signature this way and refuse anything that does not verify.

Recovery phrases: the master copy

Modern wallets show 12 or 24 English words instead of raw keys. This recovery phrase (seed) can regenerate every key, so if you lose your phone, typing the words into a new wallet restores every address and coin.

Which also means anyone who sees your recovery phrase owns your whole wallet.

Watch the 1-minute explainer · 0:49 Lose your phone — what happens to the coins? What if someone sees your phrase? Narrated; it pauses after every scene.

Read the script — full text

1. Inside. A wallet app doesn't hold coins. It holds twelve words. Keys and addresses are computed from those words, and the coins live on the chain.
2. Lost phone. So if you lose your phone, and type the same twelve words into a new one, the same math rebuilds the same keys and the same addresses, and the coins on the ledger show up again.
3. Predict. Your turn to predict. Someone saw a photo of my recovery phrase. My phone is locked, and still in my hand. What about my coins? Answer: they are at risk. They can make the same keys from the same words, sign, and move the coins to their own address. A phone lock only locks that phone. Whoever sees the phrase holds the whole wallet.
4. So. So the recovery phrase is the whole wallet. Write it on paper, keep it offline, and show it to no one.

The narration is synthesized speech.

Mobick’s paper-wallet culture

Mobick has a culture of printing private keys on paper and handing them out. Anyone can check the balance from the address on the front; only scratching the hidden key lets you spend. From the paper wallets bundled with a 2022 book to airdrops across mountains and oceans, paper was how Mobick first reached people. The paper-wallet lesson goes deeper.

How to make and keep a recovery phrase safe — broken randomness, offline generation, crossing borders — is in Keeping your seed safe.

Summary

• Coins live on the ledger; a wallet holds the key (private key) that spends them.
• Private key → public key → address is one-way. Share addresses, never keys.
• Signatures are made with the private key and checked with the public key.
• Whoever sees your recovery phrase owns your wallet.