X-Pub everything you need to know

Introduction: The concept of X-Pub plays a central role in the Bitcoin ecosystem. It allows you to manage Bitcoin addresses and keep track of your wallets without having to access your private keys. In this blog post, I'll explain what the X-Pub is how to find it and what you can use it for.

1. What is an X-Pub?

A X-Pub (Extended Public Key) is an extended public key that allows you to generate multiple Bitcoin addresses from a single seed phrase. Unlike your seed phrase, which must remain strictly confidential, you can share the X-Pub with others without revealing your private keys.

• Seed Phrase and X-Pub: The seed phrase, consisting of 12 or 24 words, generates both your private key and the public key (X-Pub). Your seed phrase is your private key, while the X-Pub is the public key used to see how much money is stored in your Bitcoin addresses.

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2. What is the X-Pub used for?

The X-Pub is used to track all Bitcoin addresses connected to your wallet. Using the X-Pub, wallets or applications can check how much Bitcoin is stored at the various addresses in your wallet.

• Generate Bitcoin addresses: X-Pub allows you to generate any number of Bitcoin addresses. These addresses can then be used to receive Bitcoin or check your account balance.
• Transparency and overview: Since the blockchain is transparent, you can use your X-Pub to see at any time how much Bitcoin is on the addresses connected to your wallet.

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3. How does the X-Pub work?

With your X-Pub, you can generate Bitcoin addresses in sequence (e.g., address 0, address 1, address 2, etc.). While the X-Pub can create addresses, it can never infer the private key. Therefore, it's safe to share the X-Pub with others as long as you don't reveal your private keys.

• Different addresses for different transactions: X-Pub allows you to create different addresses and thus separate payments. It's extremely important to improve privacy by choosing a new address for each UTXO, i.e., each time you receive new Bitcoin. This significantly improves your privacy, as there is no direct connection between these transactions.
• Multiple wallets: Additionally, you can use a single Bitcoin seed phrase to generate multiple Bitcoin wallets (X-Pubs) that are independent of each other. This can be useful for separating different Bitcoins, such as your private (No KYC) Bitcoins and the not-so-private (KYC) Bitcoins. This way, a connection can never be established between the KYC and No KYC Bitcoins. Creating another X-Pub just for, for example, Pocket Bitcoin, which then is shared, can make sense to reveal less private data.

4. Where can you find the X-Pub?

You can use your X-Pub in your Hardware Wallet, then in the Companion app your hardware wallet or in your Bitcoin software wallet. Here you can view the X-Pub and use it to manage Bitcoin addresses.

• Be careful when sharingAlthough the X-Pub doesn't provide direct access to your Bitcoin, you shouldn't share it lightly. The X-Pub contains important information about your wallet addresses and transactions that others can view. Share the X-Pub only with trusted services, or create a separate X-Pub for applications that need access.
• Blog: Import X-Pub from Specter DIY with Sparrow

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5. Different X-Pub types and formats

There are different address formats in the Bitcoin network, and each type has its own X-Pub. The most common formats include:

• Native SegWit: The native SegWit format is usually used by default today.
• Nested SegWit and Legacy addresses: If you use these formats, different addresses and X-Pub keys will be generated.

Different passphrases can also generate different X-Pubs. Each time you enter a different passphrase for the seed phrase, the associated X-Pubs, or wallets, change.

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6. Benefits of using X-Pub

• Security: Since X-Pub does not reveal private keys, it is safer to use it to generate Bitcoin addresses and track transactions.
• Convenient administration: The X-Pub allows you to keep track of different wallet addresses without having to directly access your hardware wallet.
• Privacy: By using different X-Pub keys and addresses, you can ensure that your different Bitcoin transactions are separate and not easily traceable.

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Conclusion: X-Pub as a useful tool for Bitcoin transactions

The X-Pub is an essential tool for managing your Bitcoin addresses securely and efficiently. It allows you to keep track of your wallets while protecting your private keys. However, you should be careful about who you share your X-Pub with to protect your privacy.