Launching satlink (xpub support) - Automatically buy bitcoin direct to cold storage

Launching satlink (xpub support) - Automatically buy bitcoin direct to cold storage

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16 min read

xsats-sticker-120x60@1x.png We created xsats to make buying bitcoin more easy, secure and cost-effective.

Today it becomes even easier to stack sats automatically to cold-storage, with the launch of our wallet linking feature, satlink!

Your privacy and security is our foremost concern, which is why satlink was designed in a way that maximises your privacy and security, and keeps the information you share with xsats to an absolute minimum.

satlink takes less than 5 minutes to setup and can be used with almost every hardware and software Bitcoin wallet available today!

Why self custody?

If you found this article, it's likely you already know a bit about why it's important to hold your own bitcoin (self-custody). That said, it's never a bad idea to remind oneself why it’s so important with bitcoin in particular.

Self-custody means holding your bitcoin yourself. In practice, this means only you have access to the private keys for your bitcoin. The private keys are what allow you to spend your bitcoin (and hence give you ownership) and anyone with these private keys can spend it, thereby effectively giving anyone with access to your private keys ownership of the bitcoin. The bitcoin held in custodial services is often accessible to dozens of people, meaning all of those people effectively 'own' the bitcoin. If you don't take exclusive ownership of your bitcoin, then you don't really own any bitcoin, you own an IOU.

Unlike most other services that enable you to buy bitcoin, xsats is 100% non-custodial. You are the only person who has access to the private keys for your bitcoin. The importance of this cannot be understated.

If you trust someone else to custody your bitcoin (whether it be a custodial wallet, exchange, bank or any other custodial service), you are placed in an extremely fragile situation. Even if your custodian is lead by the most trustworthy, high-integrity individual since Jesus Christ himself, you must also trust that they are 100% competent in securing often millions if not billions of dollars worth of bitcoin, in some of the largest, most centralised and accessible honey-pots ever created. This is a huge leap of faith. Any one of the employees could decide to run off with your bitcoin, or make a mistake which leads to the loss of your bitcoin. A thousand other things could go wrong; it really is not worth risking having your bitcoin held by a custodian for any long duration.

It's easy to think that trusting someone else with the responsibility of holding your bitcoin is the safer option. This is 100% false. As an individual, learning to custody your own bitcoin independently is order of magnitudes more secure for a multitude of reasons, largely summarised above, though another dedicated post would be necessary to discuss this more completely.

How does it work?

satlink works by enabling you to add something called an 'extended public key' (often referred to as an xpub) to your xsats account. Most wallets (both software and hardware) allow you to view the associated xpub for that particular wallet, or 'account' on your wallet. That is, each wallet (or account on the wallet) has an associated xpub which you can import into the xsats app to 'link' your wallet. Once it's linked, all you need to do to submit more receiving addresses in the xsats app is press a button. As always, please ensure that you have access to the addresses (i.e. can spend bitcoin from them) before sending payment to buy bitcoin with xsats.

You can read on to learn more about how this works, or skip straight to the setup guide below if you’re already familiar with xpubs.

What's an xpub?

Without getting too technical, an xpub is a special key (string of letters and numbers) associated with a particular wallet that allows a wallet or third party service (like xsats!) to generate the receiving addresses for your wallet; these are the addresses that you share with people or services when you want to receive bitcoin into that wallet.

It's important to note that, given access to this key, someone can generate and view your bitcoin addresses and therefore also view their balance, but they cannot spend your bitcoin.

Like much terminology used in Bitcoin, the name xpub (extended public key) is slightly misleading. Although someone with your xpub cannot steal your bitcoin, the xpub is still a highly sensitive piece of information in terms of privacy, as with it someone can potentially view all addresses and associated bitcoin balances for that xpub (wallet). As such, it is important that you keep your xpub secure and private.

Is satlink safe?

With bitcoin (and life in general!) it pays to be careful and make sure that you understand any possible risks associate with any actions you make.

I mentioned in the introduction, satlink has been designed to maximise your privacy and security while making automatically stacking sats to self custody easier than ever.

As described above, satlink requires that you share your wallet's xpub with the xsats app. In order to ensure that your xpub remains protected and secret, satlink was designed such that it never leaves the device used to access your xsats account. Your xpub is encrypted and stored locally on your device. It will never leave your device and is at no point ever sent to the xsats servers, meaning we never see your xpub. The best way to keep a secret is to never share it with anyone; and this is the approach we take with satlink. Since we (xsats company and team) never even know your xpub we can never be forced to hand it over to anyone and the privacy risk is minimised.

Once you have linked an xpub to the xsats app, you can then choose to queue batches of 10 receiving addresses at a time. Once queued, bitcoin bought using xsats will automatically be sent to your hardware wallet, cycling through addresses in order, so that each address is only used once. This serves to protect the present and future privacy of your bitcoin transactions. We believe financial privacy is a fundamental human right.

You are also free to delete your xpub from the xsats app at any time. Since the only place it is stored is on your device, it will be completely wiped from xsats. It can be added again at any time (see below for a how to guide).

Setup

Now that we've talked a bit about the importance of self-custody and introduced how satlink makes buying bitcoin directly to your self-custodial wallet easier, all without any loss of privacy or security, it's time to link your wallet!

A few things to note before we get started:

  • Ensure that your wallet seed phrase (the 24 words generated by your wallet when you setup, which encode your private key) is backed up and recorded safely and securely.
  • While we're on the topic, I'd also like to make a friendly reminded that you should never show anyone your seed phrase unless you want to give them all of your bitcoin. In the wake of the 2020 Ledger hacks, there is a constant stream of phishing attacks - do not be tempted to enter your seed anywhere in response to any email or other means of contact - these are all scams seeking to take your bitcoin.

Step 1: Download/Update the xsats app

If you haven't already, download the xsats app and register for an account - it only takes 5 minutes!

If you already have an account, make sure that you're running the latest version of the xsats app from the App/Play Store.

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Step 2: Retrieve an xpub from your wallet

For the purposes of this guide, we have used a Ledger Nano S hardware wallet. That said, satlink has been fully tested with a number of other wallets including the CoinKite ColdCard, BitBox02, Electrum and Specter. If you'd like help with setting up satlink on any of these wallets (or any other), please reach out to us and let us know on Twitter or via email!

Ledger

Open the Ledger Live app on either your phone or laptop.

Visit the 'Accounts' tab, then tap on '+' on the top right to add a new account.

It's important that you create a new account for the purposes of linking xsats. If you choose to link an existing account that has already been used to receive bitcoin in the past, by default your previously used addresses will be reused by xsats. However, you can also delete the used addresses from the queue within the xsats app if necessary.

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Proceed to add a new account, giving it a name of your choice (e.g. xsats satlink), using your Ledger device.

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Fetch the wallet xpub

Tap on your newly created dedicated xsats satlink wallet in the 'Accounts' menu.

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Tap on the spanner key IMG_0190.jpg

Select 'Advanced Logs' IMG_0191.jpg

Copy the long string of letters and numbers that begins with 'xpub' (it may also start with ypub or zpub). Be sure to only copy the string between the two quotation marks, i.e. excluding the quotation marks and any of the other data e.g. 'index' and 'freshAddressPath'. (Note, that if you chose to create a new account dedicated to xsats satlink, 'freshAddressPath' should end with '/0')

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Step 3: Return to the xsats app

Login to the app and visit the central tab with the Bitcoin logo.

If you're using a wallet that permits you to view the xpub as a QR code:

  • Tap on the QR icon on the top left corner and scan the xpub QR (be sure to not scan an address QR as it wont work).

Otherwise, if you don't have access to the xpub QR:

  • Tap on the xsats logo to open the satlink setup screen, then paste the wallet xpub you retrieved from Step 2 then tap 'Continue'.

Now you will see a field labelled 'Confirm 1st Address'. Return to your newly created account in your wallet app (in this case Ledger Live), copy the first receiving address generated by the wallet account you created in Step 2 (remember to verify the address using your hardware wallet if relevant), and then paste it into this field.

It is very important that you use the first address of the wallet, as it is used to verify that the addresses generated by the xsats app from your xpub match those displayed by your wallet. After you have pasted the address into the xsats app, press 'Submit'.

IMG_0195.PNG If all wen't to plan, you should see a green success message flash up and a new screen showing your wallet info as shown below. If not - please reach out to us and we'll do what we can to get you sorted ASAP.

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Tap 'Preview receiving addresses' to view the next 10 addresses and then tap on 'Queue Addresses' to queue these addresses up for your next 10 bitcoin orders.

Now when you send payment, you will automatically receive your bitcoin to these addresses, one at a time in the order that they are provided.

When you're running low on unused addresses, visit the central tab in the xsats app, tap 'Preview receiving addresses' and then 'Queue Addresses' to load the next batch of addresses ready to receive your next lot of bitcoin purchases.

And thats it! Now its even easier and more convenient to autostack sats to your bitcoin wallet.

More guides on the way - let us know if you have any suggestions!

Happy stacking!

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