Bitcoin custody is about who controls the private keys that authorize spending—not where bitcoin is physically stored. In self-custody, you control the keys and their backups. With a custodian, a company manages key access under its own security practices and agreement with you. That difference determines who can authorize transactions and who is responsible if access is lost.
What a Bitcoin wallet actually holds
Bitcoin is recorded on the Bitcoin network. A wallet is software or a device that manages the keys used to access bitcoin and authorize transactions; it does not contain bitcoin like a physical wallet contains cash. The SEC Office of Investor Education and Assistance puts it this way: “Crypto wallets do not store crypto assets themselves; instead, they store the ‘private keys’ or passcodes for your crypto assets.” SEC investor bulletin, Dec. 12, 2025
Private keys authorize spending
A private key is secret information that lets a wallet authorize a transaction. Whoever can use the key may be able to spend the associated bitcoin. Bitcoin.org cautions: “Private keys must never be revealed as they allow you to spend bitcoins for their respective Bitcoin wallet.” Bitcoin.org vocabulary
Public keys and receiving addresses
Public-key information and receiving addresses are used to receive bitcoin and verify transactions. They do not authorize spending. Keep them distinct from private keys and recovery phrases: sharing a receiving address is not the same as handing someone control of the funds.
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Recovery phrases are powerful backups
A recovery phrase, also called a seed or mnemonic phrase, is a set of words from which a wallet can be restored. Treat it as a credential, not a customer-service password: anyone who obtains it may gain access to the corresponding bitcoin. Never share it with a person claiming to be support or enter it into an unsolicited website or app.
Self-custody and third-party custody
The key question is who controls the keys and who can authorize a transaction. The labels describe different responsibilities, not a guarantee that a particular arrangement is secure.
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- Proven security at scale: Over 9 years and millions of cards issued with no known remote hacks, while military‑grade EAL6+ security keeps your private keys locked inside the chip. Your cryptocurrencies stay strongly protected from online attackers.
- Tap once to manage your entire crypto wallet across 90 blockchains - no USB cables or Bluetooth, no batteries, no setup. Access 14,100+ coins & tokens, DeFi, NFTs, and staking instantly from your phone
- Smart backup: Use your second Tangem Wallet as your Backup keys with end‑to‑end encryption; no more papers, pictures. If one card is lost, the remaining can still restore full access, with an optional seed phrase available for advanced users.
- Engineered to last up to 25 years: Waterproof (IP69K), shockproof and tested for extreme temperatures from −25°C to 50°C. A durable cold wallet with long‑term protection and independently audited security.
- Trusted by 6 million users worldwide (4.9 App Store, 4.8 Google Play) - buy, sell, swap, stake, and spend cryptocurrency directly. The secure offline storage wallet designed for how people actually use crypto wallets
| Arrangement | Who controls key access? | Who handles recovery? | Main dependency |
|---|---|---|---|
| Self-custody | You control the private keys. | You must protect the keys and maintain a usable backup. | Your device security, backup handling, and ability to operate the wallet. |
| Third-party custody | A company controls or manages access under its security practices and customer agreement; arrangements vary. | Access and recovery depend on the provider’s procedures and policies. | The provider’s security, solvency, policies, and honoring withdrawals. |
What self-custody changes
Self-custody avoids relying on a company to authorize access, but transfers the security and recovery burden to you. Theft, malware, device damage, or accidental disclosure can have direct consequences. If the key and every usable recovery backup are lost, you may permanently lose access. A wallet maker, Bitcoin developer, exchange, or custodian cannot restore a self-custodied wallet on your behalf.
What third-party custody changes
A custodian manages key access according to its own controls, policies, and agreement with the customer. You depend on that provider to safeguard the assets and honor withdrawals. Access can be affected by its security, solvency, or policies, so do not assume that every service uses the same arrangement or protections.
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- Suitable size: the cold wallet backups are compatible with BIP39 wallets, can work with most hardware wallets, supports up to 24 mnemonics seed phrases, convenient for you to use in coordination with other crypto seed storage devices and wallets
- Multiple ways of locking: you can use the matching screws to lock up the steel bitcoin wallets; You can also lock them up and hide them in other places if you still feel unsafe; The hole on the bitcoin wallet measures 6 mm/ 0.24 inch in diameter, suitable for hanging
Hot, cold, and hardware wallets
Hot and cold describe the environment in which keys are kept: hot storage is connected to the internet, while cold storage keeps keys offline. These terms do not determine who owns or controls the keys. Both an individual and a service provider may use hot or cold approaches.
Cold storage can reduce exposure to some online threats, but it does not prove a system is secure or eliminate backup and operational risks. Bitcoin.org’s wallet-security guidance discusses securing wallets and the risks of relying on online services.
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What a hardware wallet does—and does not do
A hardware wallet is a physical device used in a self-custody setup to keep key operations in a specialized device environment and sign transactions. Bitcoin.org lists hardware wallets as an offline storage option. If the device is lost and there is no proper backup, funds may be unrecoverable. The device does not protect a recovery phrase that someone else obtains, and it does not remove the need to check device and software security. Bitcoin.org’s wallet-selection guide
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Protecting keys and backups
For self-custody, the backup is part of the security system. A usable backup can help restore access after a device failure; a disclosed backup can let someone else take control. Bitcoin.org advises keeping backups secure and private, understanding how a wallet handles backups and newly generated addresses, and avoiding unencrypted backups online. Bitcoin.org wallet-security guidance
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- Keep private keys and recovery phrases secret. Do not send them in messages, store them in an exposed online document, or provide them to someone claiming to help.
- Understand the wallet’s recovery process and how it handles newly generated addresses before relying on a backup.
- Consider the tradeoff in backup locations: more than one secure physical location reduces reliance on a single location, but creates more opportunities for theft or disclosure. There is no universal placement plan for every user.
- Watch for phishing and secure online accounts with strong, unique passwords and multifactor authentication where available.
- If using an online service, assess its security and honesty as well as its convenience; Bitcoin.org warns that a service holding funds creates reliance on the third party.
How to evaluate a wallet or custodian
Compare the practical responsibilities and controls rather than relying on labels such as “cold,” “secure,” or “easy.” Bitcoin.org recommends considering control, validation, transparency, environment, privacy, and fee control when choosing a wallet. The SEC bulletin advises researching custodians, never sharing keys or seed phrases, watching for phishing, and asking about safeguards, access, and fees. SEC investor bulletin, Dec. 12, 2025
Questions for a wallet choice
- Who controls the private keys, and who can authorize a transaction?
- How are recovery and backup handled, including after device loss?
- What exposure exists to internet-connected devices or account compromise?
- How much technical work is required for ordinary use and recovery?
- What validation and transparency features does the wallet software provide?
- What privacy and fee-control features matter for your use?
Questions for a custodian
- Who can access or control the keys, and what safeguards protect that access?
- How do withdrawals work, and what conditions or delays may apply under the agreement?
- What account, transaction, transfer, setup, and closure fees apply?
- What happens to access if the provider changes its policies or its ability to operate is affected?
Fees, contractual protections, legal status, reserves, insurance, security controls, and withdrawal performance depend on the specific provider and jurisdiction. The SEC bulletin is staff investor education, not a rule or regulation, and it creates no new obligations. Verify the current agreement and disclosures for any service you are considering; general guidance cannot establish how a particular custodian operates.
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