The short answer: RecoverBull is an open-source Bitcoin wallet backup protocol built by Bull Bitcoin that allows anyone to recover a self-custodial wallet without a written seed phrase. It works by splitting the backup into three separate components stored in three different locations, so that no single breach, device loss, or server compromise can expose your funds. If you lose your phone, you can fully recover your wallet in under two minutes.
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Want to see how it works? Watch this video

If you don't own your bitcoin, someone else does

There is a principle at the foundation of Bitcoin that most people learn the hard way: if you do not hold your own private key, you do not actually own your bitcoin. You hold a promise from a company that could freeze your account tomorrow, go bankrupt, get hacked, or simply decide your funds are temporarily unavailable. Ownership without control is not ownership.

Holding your own private key is called self-custody. It gives you the ability to receive bitcoin, to spend it, and, most importantly, to recover it if you lose your phone or delete your wallet app. The private key is not managed by a platform on your behalf. It lives on your device, under your exclusive control, and no one else can move your funds without it.

This is the core promise of Bitcoin. The problem is that for most newcomers, the path to self-custody has a serious and underappreciated gap.

The onboarding problem that keeps driving people toward custodial wallets

The scenario is familiar to anyone who has introduced someone to Bitcoin. You are at a bar, at a family dinner, or at a meetup, and you make a friend download a wallet so you can send them a small amount. The interaction goes well. A few months later, they check and the bitcoin is gone. They never backed up their wallet properly, they got a new phone, they forgot the app existed, or they simply lost access without understanding what that meant and without any path to recover it.

The obvious answer would be to tell them to buy a hardware wallet, engrave a seed plate, and add a passphrase. But that is not a realistic introduction for someone who just received their first satoshis and is still deciding whether Bitcoin deserves their attention. They will get to cold storage as their stack grows. The problem is that in the meantime, their bitcoin is unprotected.

The tempting shortcut is to tell them to download a custodial wallet like Wallet of Satoshi instead. That solves the backup problem by eliminating self-custody entirely, which defeats the purpose. The goal was to give them their own bitcoin, not to hand that bitcoin to a platform that holds it on their behalf.

The Bull Bitcoin team built RecoverBull to fit exactly this gap: an open-source backup protocol that allows newcomers to recover their wallet without a seed phrase, without giving custody to anyone, and without requiring more than two minutes to set up.

What RecoverBull is

RecoverBull is an open-source encrypted Bitcoin wallet backup protocol developed by Bull Bitcoin, the Bitcoin-only exchange founded in Canada in 2013 and now available in Canada, Europe, Mexico, and Costa Rica. It is built directly into BULL Wallet and provides a secure recovery path for self-custodial wallets without requiring the user to write down or manage a BIP-39 seed phrase.

RecoverBull is best understood as an onboarding tool and a safety net. It gives newcomers a recoverable wallet from day one, before they are ready for the discipline of cold storage. As their stack grows and their knowledge deepens, they can move to a hardware wallet with a physical seed phrase backup. RecoverBull is not meant to replace that step. It is meant to protect them during the period before that transition happens.

Unlike services like Ledger Recover, which require your seed material to leave your device and be held in encrypted fragments by third-party custodians, RecoverBull never gives any party access to your password or your keys. Even if Bull Bitcoin were compelled by a court order, it has nothing to hand over that would give anyone access to your wallet, because it never held your password.

RecoverBull requires no account, no email address, and no KYC of any kind. The source code is available at github.com/SatoshiPortal/recoverbull and the full technical specification is at recoverbull.com.

How RecoverBull works: splitting a secret into three parts

The security of RecoverBull rests on a single principle: no individual component of the backup should be sufficient to access your bitcoin on its own. This is achieved by splitting the backup into three separate parts stored in three separate locations, each of which is useless without the other two.

Part one: the encrypted backup file.
⁠When you set up RecoverBull in BULL Wallet, the wallet generates an encrypted backup file containing your wallet seeds. This file is encrypted on your device before it goes anywhere. You can save it to Google Drive, iCloud, a USB drive, or any local folder. Cloud storage is actually a safe choice here: the file is fully encrypted and contains nothing that reveals what it is or who it belongs to. The only risk is saving it exclusively on your phone: if you lose your device and the file only exists locally, it is gone with it.

Part two: an encrypted key on an anonymous Tor server.
⁠The encryption key that protects your backup file is not stored on your device or in your cloud account. You choose a password, and BULL Wallet uploads an encrypted version of that key to a separate server over the Tor network. The server never sees your IP address, there is no account, no email address, and nothing tied to your identity. Not even Bull Bitcoin knows who is using it or which backup belongs to which user.

Part three: your password.
⁠The key stored on the server is itself encrypted with your password, which only you know and which is not saved anywhere in the system. If someone has access to both the server data and your backup file but does not know your password, they cannot recover anything. And if they try to guess, the server blocks access after three failed attempts per day, which means a brute-force attack would take years.

To recover your wallet, you need all three components together. Remove any one of them and recovery is not possible.

What happens if one component is compromised

If someone hacks your Google Drive: they find your encrypted backup file, but without the vault key from the server and your password, they cannot decrypt it. The file is useless on its own.

If someone hacks the key server: ⁠they find encrypted keys with no names, no accounts, no Bitcoin addresses, and no way to match any key to any user or any backup file. Even if they could break the encryption on individual keys, they would still need the backup files that are stored separately in individual cloud accounts.

If someone learns your password: they have one component out of three. Without the backup file and the vault key, the password alone cannot recover any wallet.

If you lose your phone: you install BULL Wallet on a new device, retrieve your backup file from your cloud storage, enter your password, and BULL Wallet contacts the server over Tor to retrieve and decrypt the vault key. Your wallet is fully restored in under two minutes.

Step by step: how to set up RecoverBull in BULL Wallet

Step 1: Download BULL Wallet
⁠BULL Wallet is available free on iOS and Android at wallet.bullbitcoin.com. No account or email address is required.

Step 2: Receive bitcoin and follow the backup prompt
⁠RecoverBull does not require any setup on an empty wallet. As soon as you receive your first bitcoin, BULL Wallet prompts you to secure it. At that point you choose between two options: write down your seed phrase the traditional way, or set up an Encrypted Vault using RecoverBull.

Step 3: Choose Encrypted Vault and save your backup file
⁠If you select the Encrypted Vault, BULL Wallet generates your encrypted backup file and prompts you to save it. Choose Google Drive, iCloud, or any storage location you already use, and make sure not to save it only on the device itself.

Step 4: Choose your password
⁠Your password is the component that only you know. It is not stored on any server, in any app, or by Bull Bitcoin. Choose something strong that you will remember, because if you forget it, recovery through RecoverBull is no longer possible. Maintaining a written seed phrase as a fallback remains a good practice for exactly this reason.

Step 5: Verify the backup
⁠BULL Wallet asks you to confirm that the backup works before marking setup complete. This step is not optional. A backup that has never been tested is a backup of unknown reliability.

How recovery works after losing your phone:

1. Install BULL Wallet on the new device.
2. ⁠Select "Restore from encrypted backup."
3. Retrieve your backup file from your cloud storage.
4. Enter your password.
5. BULL Wallet contacts the server over Tor, retrieves the encrypted vault key, decrypts it with your password, and restores your wallet.

The full recovery process takes under two minutes.

Use case: onboarding someone to Bitcoin self-custody in under two minutes

This is the primary use case RecoverBull was built for. You are with someone at a bar or a family dinner. They have never held bitcoin and you have five minutes.

You have them download BULL Wallet, walk them through creating a wallet, set up RecoverBull with their Google Drive account and a password they will remember, and send them some bitcoin. The entire setup takes under two minutes. They now hold their own private key, with a recovery path that works if they lose their phone in three months, without requiring them to understand seed phrases, hardware wallets, or BIP-39 key derivation standards.

RecoverBull does not assume that newcomers will immediately adopt cold storage best practices. It gives them a working self-custodial setup with a safety net, and lets them build their understanding from there at their own pace.

Use case: traveling without Bitcoin on your phone

If you are crossing a border and would rather not carry a Bitcoin wallet on your device, you can delete the app entirely before you reach the checkpoint. Your backup file remains in your cloud storage, and your password remains in your head. When you arrive at your destination, you reinstall BULL Wallet, retrieve the file, enter your password, and your bitcoin is back in under a minute. You travel with no hardware wallet to carry, no seed phrase to hide, and nothing on your phone that could attract the attention of malicious observers, whether at a checkpoint, in a hotel room, or anywhere along the way.

The same logic applies in more serious situations. For someone fleeing a totalitarian regime with no time to prepare, the ability to carry your bitcoin in your memory and restore it anywhere in the world in under two minutes is not a convenience feature. There is no hardware wallet to confiscate, no seed phrase to find, and no account to freeze. BULL Wallet is free and open-source, with no KYC, no account, and no company that can block your access to your own funds. Anyone on earth can use it.

To be clear, this setup does not replace a proper hardware wallet and a physical seed phrase backup for long-term savings. But some situations are not ordinary, and in those situations, this may be exactly what is needed.

RecoverBull vs. custodial wallets

The default alternative when onboarding a newcomer is to direct them to a custodial wallet like Wallet of Satoshi. It is technically easier to explain, and it carries the same fundamental risk: the user does not own their bitcoin. The platform does, along with all the counterparty exposure that implies.

If the platform is hacked, freezes withdrawals, goes bankrupt, or decides your account is out of compliance, your bitcoin is at risk. This has happened repeatedly throughout the history of Bitcoin, at services that appeared reliable until they were not.

RecoverBull makes it possible to give newcomers something better: direct self-custody from the first satoshi, with a backup system that requires no more technical knowledge than knowing a cloud storage password and remembering a passphrase. The tradeoff is that the key server introduces a dependency that a physical seed phrase does not, but it is a manageable and well-designed tradeoff, and it is categorically better than handing custody to a third party.

What RecoverBull is and what it is not

RecoverBull is:

• An open-source encrypted backup protocol for self-custodial Bitcoin wallets

• An onboarding tool that makes self-custody accessible in under two minutes without a seed phrase

• A practical tool for travel, border crossings, and situations where carrying a hardware wallet is not desirable

• An alternative to custodial wallets for newcomers who are not yet ready for cold storage

• Non-custodial at every step: Bull Bitcoin has no access to your keys, your backup file, or your password

RecoverBull is not:

• A replacement for a hardware wallet or a multi-signature setup

• A substitute for a physical BIP-39 seed phrase backup for long-term savings

• Appropriate as the sole security layer for a large or long-term Bitcoin stack

• A custodial product of any kind

For someone accumulating bitcoin for the long term, a COLDCARD, Passport, or Ledger with a properly stored seed plate remains the right answer. RecoverBull is for the period before that, and for the spending wallet that sits alongside it.

Technical details

RecoverBull stores wallet seeds in an encrypted vault file formatted as UTF-8 encoded JSON. The vault key, which is the encryption key for that file, is stored in the platform-native secure storage on the device. When RecoverBull is configured, the vault key is encrypted with the user's password before being uploaded to the key server, which means the server never receives the key in a form it can use or associate with any user.

The key server operates exclusively over Tor and stores no user-identifying metadata. It cannot associate any stored key with a Bitcoin address, a user identity, or a transaction history. Access is rate-limited to three failed authentication attempts per day, which makes brute-force attacks on passwords computationally impractical.

BULL Wallet tracks backup status at the wallet level and considers a backup complete only after the user has passed the verification step, so that stored backups are confirmed to work rather than assumed to.

For the full technical walkthrough from the CEO of Bull Bitcoin: RecoverBull, the new Bitcoin wallet backup technology

Full technical specification: recoverbull.com | Open-source repository: github.com/SatoshiPortal/recoverbull

FAQ

What is RecoverBull?
⁠RecoverBull is an open-source Bitcoin wallet backup protocol that allows users to recover a self-custodial wallet without a written seed phrase. It works by splitting the backup into three components: an encrypted file stored in the user's cloud storage, an encrypted vault key on an anonymous Tor-accessible server, and a user-chosen password. All three components are required for recovery, and none of them alone is sufficient to access any funds.

Is RecoverBull safe?
⁠Yes, for its intended use case. RecoverBull protects against the most common causes of Bitcoin loss: losing a device, getting a new phone, and having cloud storage breached. No single compromised component exposes funds, and the key server blocks access after three failed password attempts per day, making brute-force attacks impractical. The tradeoff is a dependency on key server availability that a purely offline seed phrase does not have. For a spending wallet or an onboarding setup, RecoverBull represents a well-considered and appropriate security model. For long-term savings, combining it with a hardware wallet and a physical backup provides the strongest overall setup.

What is a vault key?
⁠The vault key is the encryption key that protects your RecoverBull backup file. The backup file contains your wallet seeds in encrypted form, and the vault key is what decrypts them. RecoverBull stores the vault key separately from the backup file, on an anonymous Tor-accessible server encrypted with your password, so that neither the file nor the key alone can restore your wallet.

What happens if I forget my RecoverBull password?
⁠Recovery through RecoverBull becomes impossible, because the password is not stored anywhere in the system. This is by design, and it is the reason maintaining a written seed phrase backup as a fallback remains important. If you have your BIP-39 seed words, you can recover your wallet on any compatible application regardless of the RecoverBull password.

How is RecoverBull different from just saving a wallet backup to the cloud?
⁠A standard cloud backup stores your wallet data in a form accessible to anyone who can access your cloud account. RecoverBull encrypts the backup file before it leaves your device and stores the decryption key on a separate anonymous server. Even if someone compromises your cloud storage, they have a file they cannot open. Even if someone compromises the key server, they have encrypted keys with no associated identities and no backup files to match against them.

Can I delete my wallet and restore it later?
⁠Yes. If you delete BULL Wallet from your phone and reinstall it later, you can restore your wallet completely from your backup file and your password. This is what makes the border crossing and travel scenarios practical.

What happens if the key server goes offline?
⁠If the key server becomes permanently unavailable, recovery through RecoverBull using that server is no longer possible. This is one of the reasons RecoverBull is designed to complement rather than replace a physical seed phrase backup. The protocol is open-source and any operator can run a key server, which distributes the risk across multiple independent parties.

Can Bull Bitcoin access my funds through RecoverBull?
⁠No. Even if Bull Bitcoin were compelled by a court order, it has nothing to hand over that would give anyone access to your wallet, because it never held your password.

Can I run my own key server?
⁠Yes. The protocol is open-source and the key server software is freely available at github.com/SatoshiPortal/recoverbull. Any individual or organization can run their own server, which eliminates the dependency on third-party infrastructure entirely.

How does RecoverBull compare to other Bitcoin backup methods?

Start today

RecoverBull is built into BULL Wallet and requires no account, no email address, and no prior experience with Bitcoin backups. For newcomers, it is the fastest path to self-custodial Bitcoin without handing custody to a platform. For Bitcoiners who bring others into the space, it is the tool that makes onboarding responsible and recoverable from the very first satoshi.

Download BULL Wallet
⁠BULL Wallet is Bull Bitcoin's self-custodial, open-source Bitcoin wallet, available free on iOS and Android. Your private keys are generated on your device and never leave it. RecoverBull is built in.

Download BULL Wallet for iOS and Android

Watch the full technical breakdown ⁠For the full cryptographic architecture of the protocol, watch the in-depth video from Francis Pouliot, CEO of Bull Bitcoin: RecoverBull, the new Bitcoin wallet backup technology

Learn more about RecoverBull
⁠Full technical documentation and whitepaper: recoverbull.com Open-source code: github.com/SatoshiPortal/recoverbull

Need help?
⁠Reach the Bull Bitcoin support team directly through the chat box inside the wallet.