Hot and cold describe where a wallet's private keys live, not where the coins are. A hot wallet keeps its keys on a phone, computer or browser that is online; a cold wallet keeps them on a dedicated device or on paper that stays offline and signs only when you physically approve. Coins move between the two with an ordinary transaction, so many holders use both. Storage protects access, not price: crypto is volatile and can fall by most or all of its value in any wallet. The crypto hub covers the basics of buying and holding.
What is the difference between a hot wallet and a cold wallet?
A hot wallet's keys sit on a device connected to the internet, while a cold wallet's keys stay on hardware or paper that never goes online.
NIST's overview of token custody draws the line by purpose. Hot wallets hold low-value funds in transit that need to be reachable; cold wallets hold high-value funds at rest, and every signature needs a physical act such as pressing a button, entering a PIN on the device or scanning a QR code. The SEC's investor bulletin adds that cold devices, while safer from cyberthreats, can still be lost, damaged or stolen.
What separates them is attack surface. Every app, browser tab and network connection on a device that holds keys is a path an attacker can try, and a device that does nothing but sign closes most of those paths. None of this changes who owns the coins; that separate question is covered in custodial vs non-custodial wallets.
How do software, hardware, paper and multisig storage compare?
Each step away from an always-online app removes ways to steal the keys but adds cost, setup time or extra steps every time you spend.
| Storage type | Where the keys live | Main attack surface | Cost | Convenience | Typical way it fails |
|---|---|---|---|---|---|
| Phone or desktop app (hot) | Encrypted on an internet-connected device | Malware, phishing, fake apps, device theft | Free to install; network fee per transaction | Highest: pay or trade in seconds | A compromised device drains the wallet |
| Browser extension (hot) | Inside the browser profile | Malicious sites, rogue extensions, requests you approve without reading | Free; network fee per transaction | High for web apps and DeFi | Approving a transaction or token permission that empties it |
| Hardware wallet (cold) | A secure chip on a dedicated device that never exports the key | Tampered devices, fake firmware, phishing for the phrase, blind signing | One-off device purchase | Medium: the device is needed for every send | A recovery phrase someone else has seen, or none at all |
| Paper wallet (cold) | Printed or handwritten key or phrase | Anyone who sees or photographs it; fire, water, fading | Almost nothing | Low: spending exposes the key to an online device | Destroyed or copied paper |
| Multisig (usually cold) | Several keys on separate devices or with separate parties | Losing too many keys or the wallet's configuration | Several devices plus setup time | Lowest: more than one device per send | The owner or heirs cannot assemble enough keys |
Software wallets. Phone and desktop apps and browser extensions cost nothing and are quick to use, which suits spending money, but their keys share a general-purpose device with a browser, email and dozens of other apps. The CFTC advises downloading wallet apps only from the developer's official website.
Hardware wallets. A small dedicated device, usually with its own screen and buttons, keeps keys in a secure chip and will not export them, which NIST notes shields the key from malware while still letting you sign. You need it at hand for every send, and you still depend on the written recovery phrase if it breaks or goes missing.
Paper wallets. A private key or recovery phrase written or printed on paper, often with a QR code, costs almost nothing and has no electronics to attack. FINRA still advises against printing keys, because paper can be lost, destroyed or read by anyone who handles it, and spending means typing or scanning the key into software.
Worked example: Spending part of a paper wallet's bitcoin
A paper wallet's address holds 0.10 BTC. You scan its key into a phone wallet to pay someone 0.02 BTC, with a network fee of 0.0001 BTC.
- Bitcoin spends whole outputs, so the transaction uses the full 0.10 BTC as its input.
- Outputs: 0.02 BTC to the payee and 0.10 − 0.02 − 0.0001 = 0.0799 BTC back as change.
- Depending on the wallet, that change can go to a new address derived from the phone wallet's own seed rather than back to the paper address.
The paper may now control nothing, while 0.0799 BTC depends on the phone wallet's backup, and the paper key has been exposed to an online device. Sweeping the whole balance into a newly created wallet in one transaction avoids leaving coins behind a key that is no longer secret.
Multisig. A multisignature wallet needs m of n keys to approve a payment, for example 2 of 3. NIST compares it to a lockbox with several keys: access survives the loss of one key as long as enough remain, and one of its examples keeps a key on a phone, one in a bank vault and one with a third-party custodian. The cost is complexity: three devices or apps, three backups and a copy of the wallet's configuration listing all three public keys, without which the addresses cannot be recreated.
How does a hardware wallet sign transactions offline?
The private key never leaves the device: your computer or phone prepares an unsigned transaction, the device displays it, and only the finished signature comes back.
- Build. The online companion app picks the coins to spend, the destination and the fee, and packages them as an unsigned transaction. For bitcoin, the BIP 174 format, a partially signed bitcoin transaction or PSBT, carries everything a signer needs, so the signer can stay offline.
- Transfer. The transaction reaches the device by USB cable, Bluetooth, memory card or QR code. Air-gapped devices use only the last two, so no cable or radio link ever joins them to an online machine.
- Display. The device shows the destination address, amount and fee on its own screen. NIST calls this secure display, or what you see is what you sign: malware can change what the computer shows, but not what the device shows.
- Approve. You confirm with a button press or PIN on the device itself.
- Sign and return. The key signs inside the secure chip, and only the signed transaction goes back to the app for broadcast.
Step 3 is where most of the protection lives and where most failures happen. In February 2025, attackers the FBI linked to North Korea took about $1.5 billion from one exchange's multisig cold wallet; Ars Technica's reconstruction found they had tampered with the web interface the signers used, so a malicious transaction looked routine. Devices that cannot show a transaction in readable form, known as blind signing, offer far less protection, because you approve whatever the computer sent.
What supply-chain risks come with buying a hardware wallet?
A device can be compromised before it reaches you, through altered hardware, swapped packaging, fake firmware or a recovery phrase that someone else already knows.
The risk is real. On October 28, 2026, the Singapore Police Force warned that hardware wallets bought from some retail stores in Singapore contained malicious components able to capture recovery phrases or private keys; at least two victims had lost about S$3.5 million since September 10. Police advised anyone with a suspect device to stop entering the phrase and move remaining coins to a new wallet with a newly generated phrase, on a device that has not been compromised.
- Buy from the maker or an authorized reseller. Avoid secondhand devices, marketplace listings and sellers you cannot verify.
- Reject any device that arrives set up or with words supplied. A genuine device creates the recovery phrase itself and shows it only on its own screen.
- Install firmware only through the maker's official app or site, typing the address yourself. NIST calls checking a device's integrity, for instance by verifying the supplier's digital signatures on the device and its updates, essential.
- Treat unsolicited contact as hostile. A device you did not order, or a message offering wallet verification or recovery help, is a lure.
How do you set up a cold wallet safely?
Generate everything yourself on a device you have checked, write the phrase down offline, prove the backup works, and only then move in more than a test amount.
Cold wallet setup checklist
- Inspect the packaging and seals, and confirm the device has never been initialized.
- Download the companion app from the maker's official site, typed in by hand, and run its authenticity check if it offers one.
- Update firmware only through that app, and confirm the update on the device screen.
- Create a new wallet and copy every word of the phrase onto paper or metal as the device shows it; never type, photograph or scan the words.
- Choose a device PIN unrelated to your phone PIN, birthday or bank card.
- Before funding, wipe the device, or use a second one, and restore from the written words; check that the same first receiving address appears.
- Send a small amount in, confirm it arrives, then practice a small send out so the process is familiar.
- Store the written backup apart from the device, and note for your heirs where each one is kept.
How to store crypto safely goes further on where backups should live, passphrases and a yearly check, and crypto inheritance planning covers how heirs gain access.
How much should you keep in a hot wallet?
The CFTC's guidance is to keep only funds you are ready to spend or trade in an internet-connected wallet and the rest in cold storage.
A hot wallet sized to a month or two of spending caps the damage from a stolen phone or a bad approval, and the rest sits in cold storage, moved over in planned refills. Coins left on a trading platform depend on the platform's security rather than yours; whether crypto is safe on an exchange explains how platforms split customer coins between hot and cold wallets.
Worked example: Splitting $15,000 between a phone wallet and a hardware wallet
Assume $15,000 of crypto, about $300 a month of spending or trading from a phone, a hardware wallet costing $150 and a network fee of about $2 per refill. These figures are illustrative.
- Hot wallet cap at two months of use: 2 × $300 = $600, or 4% of holdings
- Cold storage: $15,000 − $600 = $14,400
- Device cost against what it protects: $150 ÷ $14,400 = 1.04%, paid once
- Refills every two months: 6 × $2 = $12 a year
- Worst case if the phone is compromised: $600 lost instead of $15,000
Run the same arithmetic on $1,000 and the device costs 15% of the balance, which is why small holdings often stay hot or with a custodian until they grow. The split does nothing for market risk: if prices halve, the hot part falls to $300 and the cold part to $7,200. The bitcoin price page shows how far a single coin has swung, and the crypto profit calculator works out the gain or loss on a position.
What are the downsides of each storage type?
Hot wallets are most exposed to remote theft, cold wallets to loss and user error, paper to damage and copying, and multisig to setup mistakes.
- Hot wallets. Malware, phishing pages and malicious signature requests can drain them in seconds, and a stolen phone without a strong screen lock is an open wallet. FINRA warns that losing a phone whose app holds your keys can mean losing the assets for good if there is no backup.
- Hardware wallets. Devices can break, develop defects, get lost or be stolen, and FINRA notes they are not immune to sophisticated hacking. The coins survive a broken device only if the recovery phrase does.
- Paper wallets. Paper burns, soaks, fades and can be photographed without your knowledge, and partial spends can strand change, as the example above shows.
- Multisig. More keys mean more backups and more ways to get the setup wrong, and heirs who do not know which keys and records are needed may be unable to use the wallet.
- Every type. No wallet protects against price swings, since crypto can lose most or all of its value, and none can reverse a payment sent to the wrong address or chain; sent crypto to the wrong network covers what can sometimes be recovered. Fake support agents target every kind of wallet, and crypto scams lists their scripts.