Buying Passport privately USING Coinjoin

What is coinjoin?

Coinjoin is a form of collaborative Bitcoin transaction where two or more users create a transaction that provides ambiguity about the ownership of the transaction outputs. This takes place without a user needing to trust any other user participating in the transaction.

Imagine you and nine friends all throw a $10 note into a box, shake the box around, and then each pick out a note at random. Nobody would know who ended up with whose original $10 bill!

Coinjoins can take many different shapes and sizes but are always performed in a non-custodial fashion, meaning that you never lose control of your bitcoin when participating. Anytime you’re participating in a ‘coinjoin’ that asks you to send all your Bitcoin to an address not under your control, beware. So called ‘Mixers‘ like this operate in a custodial fashion and have been known to steal people’s bitcoin. Tread extremely carefully and only use tools that are well vetted.

The most common type of Coinjoin is known as an ‘Centrally Coordinated’ one, where there are often many participants in each transaction. An example of this is the Samourai Wallet Whirlpool implementation. In this type of setup, multiple users connect to a central coordinator which acts as a the central authority between all participants. The coordinator never gains control of any funds or learns anything about the participants. Its main functions are to coordinate the transaction (which becomes difficult to do purely in a peer-to-peer fashion as more participants are added) and collect a fee for maintaining the service.

Whirlpool coinjoin example with 5 participants

Why coinjoin?

Traditional finance offers fairly good levels of privacy from certain parties. For example, your employer doesn’t get to see how you spend your paycheck, and the Barista at Starbucks doesn’t get to see how you spend the change from the $20 bill you used for your morning latte.

Due to Bitcoin’s completely transparent ledger, it’s more challenging to maintain your privacy in the above examples – unless you embrace basic privacy practices when interacting with Bitcoin! In addition to being transparent, the Bitcoin blockchain is also permanent. Every transaction you make is copied to thousands of nodes (or computers) around the world to be stored indefinitely.

These two properties of Bitcoin (transparency and permanency) make it trivial for even semi-sophisticated actors with time and resources to track the flow of funds across the blockchain, at any time they like. The mistakes you make today could easily be used against you in the coming years by anyone with the ability and desire to interpret this public information.

Coinjoins provide Bitcoiners with a way to prevent against such attacks and regain some privacy. Coinjoins allow you to prevent your employer, Starbucks Barista, or even worse – a chain surveillance firm (whose job it is to track entities on the blockchain) – from tracking your spending habits. This gives you the ability to spend or save in the same way you would with physical cash, without fear of retribution at some arbitrary point in the future.

what is a payjoin?

Aside from the commonly used ‘centrally coordinated’ coinjoins, consisting of a larger number of users that each receive back the same amount they put in (less any fees), there is also Payjoin. Payjoins are peer-to-peer coinjoins, generally between just two parties. Payjoins are more commonly used when transferring value from one person to another, like buying a new hardware wallet!

Payjoins enable Bitcoin value transfer between two parties, whilst breaking something called the ‘Common Input Ownership Heuristic’ (CIOH). This heuristic used by chain surveillance firms to try and interpret the flow of funds across the blockchain. These firms do this by assuming that all of the inputs to a transaction belong to the same entity, which is true of most typical Bitcoin spends, but not with Payjoin!

As with any normal bitcoin transaction where value is being transferred from one person to another, during a Payjoin transaction the recipient gains the desired amount of Bitcoin from the sender, receiving at least one transaction output (the payment). Where a Payjoin differs is that the recipient also provides an input to the transaction, completely undermining the CIOH and casting doubt over the true flow of funds. The resulting transaction looks no different to any other typical spend, with only the two participants knowing they just completed a coinjoin whilst also transferring value from one to the other.

The other beautiful part about Payjoin is that due to the nature of how these transactions are constructed, the actual value transacted between the two parties is not visible to anyone looking at the blockchain. We’ll demonstrate this in the steps that follow.

buying passport with a payjoin

Currently there are only a few wallets able to send and receive Payjoins that adhere to the BIP78 standard. Sparrow Wallet is a great example, and will be used to demonstrate how you can purchase a Passport with a Payjoin. The receiver side of this transaction will be the Payjoin compatible BTCPay Server, which operates as our in-house Bitcoin payment processor.

First off: head to our website, add Passport to your cart, and then head to the checkout to provide contact and shipping information. Once that’s complete, choose Bitcoin as your payment option and click ‘Proceed To BTCPay’.

Passport order ready to be place

Next you’ll be greeted with an invoice which you can choose to pay using the Lightning Network, or in this case, regular ‘on-chain’ Bitcoin. The QR code shown is an encoded version of the receive address for sending using a standard transaction. For Payjoin, navigate to the ‘Copy’ tab and copy the Payment Link provided.

Invoice QR
Invoice ‘copy’ field

Using a hot wallet in Sparrow, open the Send tab and paste the payment link into the ‘Pay to’ field. Sparrow will then populate the recipient address and amount, and will store the remaining info for a following step in the process. Give the transaction a label, adjust your miner fee and click Create Transaction.

Transaction built

On the next screen you can review the transaction details. Note the blank ‘Payjoin input’? We’ll get to that next.

Transaction Summary

Click ‘Sign’ to authorize the first part of the transaction.

Transaction ready for signing

Now we have the option to Get Payjoin Transaction. This uses the information provided from the payment link copied earlier to contact the Foundation Devices BTCPay Server to obtain the details of the UTXO to be used as the missing input in our Payjoin.

Payjoin coordination ready

Recipient Payjoin input obtained and the final transaction is ready to sign.

Payjoin input obtained

Payjoin signed and ready to be broadcast to the network.

Final transaction for broadcast

The BTCPay Server will automatically detect the incoming payment and mark your order as confirmed!

Order complete

transaction analysis

This image is a block explorer view of the transaction demonstrated above, with added annotations to explain the makeup of the transaction. Some key things to note:

  • Both sender and recipient have one input and one output each
  • The actual value transferred for the purchase during the transaction was 0.00511928 BTC (see the invoice above), this amount is not visible
  • The transaction has cast doubt over the true flow of funds and improved the privacy of both participants
Click to open transaction in a blockchain explorer

The receiver has contributed a UTXO of 0.00583881 BTC to the transaction and finished up with a UTXO of 0.01095809 BTC. Subtract one from the other and you get the exact value of the invoice 0.00511928 BTC.

other privacy considerations

Spending via Payjoins or by using the outputs from larger coordinated coinjoins is a fantastic way to preserve your privacy at the Bitcoin network level. It’s also worth noting that those two options can be combined for even greater effect – Coinjoin with Whirlpool, then use those mixed outputs to create a Payjoin spend!

There are unfortunately many other things to consider when attempting to spend Bitcoin privately, or when ordering Bitcoin related items online. We plan to cover these in future articles, but will summarize them below for awareness.

(1) Purchasing using Bitcoin directly from an exchange

Are you comfortable with the exchange (or trading partner if using a peer-to-peer method) knowing you’re spending to a Bitcoin related company? If not, make use of the Coinjoin tools outlined in this article.

(2) Purchasing using a credit card

Are you comfortable with your bank knowing you’re spending to a Bitcoin related company? If not, purchase using Bitcoin that has been obtained in a private manner or has been coinjoined.

(3) Getting items shipped to your home address

Are you comfortable with the company you’re purchasing from knowing your home address? Are you aware of their data retention policies? How about a curious courier that might see a Bitcoin logo on one of your packages? If not, opt to get the items delivered to a PO box, re-mailer or similar service. The options available to you will depend on your jurisdiction.

(4) Getting items shipped using your real name and telephone number

Once again, are you aware of the company’s data retention policies? Do they have a good track record for keeping customer data secure? You could use a pseudonym and a phone number that is not tied to your personal identity.

The holistic approach

Bitcoin privacy is a multifaceted beast with many things to consider, nobody gets it perfect first time. The key thing to remember is that there’s never a bad time to start improving your privacy. Pick one aspect, make a change, then move on to the next to ensure you don’t get overwhelmed. Stay tuned for more articles on the subject, and if you need personalized support consider checking out our Concierge service.

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Order Passport Batch 2 today, limited to 2400 units!

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Introducing concierge setup

Support for all bitcoiners

One of the beautiful things about Bitcoin is that it attracts people from all walks of life, each with differing time constraints, skill sets and learning preferences. At Foundation, we pride ourselves on producing beautiful devices that are both secure and intuitive. To compliment our hardware we also strive to provide support options that cater to our diverse user base. In a recent blog post, we covered some of the ways in which we try to do this, including a catalogue of videos detailing everything from getting started with Passport, to creating your own sovereign multisig wallet with Specter Desktop. We also have a documentation website, email support, online live chat, and a vibrant Telegram community chat.

We recently announced our stunning new hardware wallet, Passport Batch 2, and its new mobile app Envoy. Our original Founder’s Edition Passport is already easy to set up and pair with a software wallet, but with the addition of an improved user interface (also coming to the Founder’s Edition) and our tailor made companion app, we have taken that ease-of-use to the next level. But we still thought we could do more…

Introducing concierge setup

Launching alongside the new Passport Batch 2 and Envoy, we are proud to announce the launch of our 1-on-1 support service, Concierge Setup. We created this service after realizing that no matter the thoroughness of our documentation, video guides and community, some users find great value in a more personalized touch. We think the ability to have someone on-hand who is experienced and has completed this task a thousand times over is an incredibly valuable option.

Our Concierge Setup service gives you direct access to our in house Bitcoin and Passport expert for a 1 hour call for your own personalized Passport onboarding experience. There is no requirement for you to be on camera or share any personal information throughout the call. During your Concierge call (which takes place via our own private Jitsi meeting server), you will learn how to:

  • Set up and configure Passport
  • Update Passport’s firmware
  • Backup your private keys to microSD and/or seed words
  • Pair Passport with Envoy (or an alternative software wallet of your choosing)
  • Send and receive to and from your cold storage
  • You’ll also have the opportunity to ask any related questions to learn more about Passport and best practices

Concierge booking

Booking Concierge Setup is simple, just head to foundationdevices.com/passport and add the item to your cart (further down the page). Alternatively, we’ll ask if you want to purchase the service alongside your Passport order.

Concierge cart add on

When your Passport ships, you’ll receive an email invite to our booking page where you can choose a date and time to suit you.

Concierge booking screen

After choosing your time slot, leave your name (or pseudonym) and email address for the invite to be forwarded to.

Booking summary

You’ll then get a confirmation with all of the meeting details (this will also be emailed to you). The booking tool also has functionality to automatically add the booking to your chosen calendar software.

Booking confirmation

And that’s it – our Bitcoin expert will be ready and waiting at the time of the meeting to help you progress along your journey to Bitcoin sovereignty!

Finally, Concierge Setup isn’t just for brand new Passport users. If you already have a Founder’s Edition but think you might benefit from some personalized instruction to get the best from your device, book a session! Need help with creating a multisig wallet using Sparrow Wallet and Passport? Book a session! Want to review your security practices with an experienced Bitcoiner – book a session! If you’ve already purchased Concierge Setup and have not received a booking link, fear not, all booking emails will be sent out when we ship Passport Batch 2 next month.

purchase PASSPORT

Order Passport Batch 2 today, limited to 2400 units!

$259.00Add to cart

Introducing Passport Batch 2 & Envoy Mobile App

Last November, we announced that Passport Founder’s Edition sold out to rave reviews. With nearly 1000 of our next-gen Bitcoin hardware wallet in the wild, the Foundation team has worked tirelessly behind the scenes to prepare for Batch 2.

We are beyond excited to share all the details with you today.

Passport Batch 2 was an opportunity to go back to the drawing board. Faced with supply chain challenges, rising component costs, and a sizable wishlist of improvements, we asked ourselves – how can we reduce costs while delivering the industry leading Bitcoin hardware wallet?

But more than that, we knew that Passport needed a companion. A way to streamline onboarding, firmware updates, and learning. A refreshingly simple Bitcoin wallet experience.

So today we are announcing not one, but two new products: Passport Batch 2 and Envoy mobile app! 

Passport Batch 2

After shipping Passport Founder’s Edition and surveying our customers, we went heads-down into design mode for Batch 2. This new Passport is the culmination of months of design and engineering work.

Price

The most common feedback on Passport Founder’s Edition was cost – its $299 price point was steep, especially compared with other hardware wallets.

By redesigning Passport Batch 2 and putting every component under the microscope, we reduced both the cost of materials and assembly. Passport Batch 2 presells for $199. Once we begin shipping, Passport’s price will increase to $249.

Design

Ultra-minimalism is everywhere, and the Foundation team is sick of it! Rather than pursuing a minimalist, boring design, Passport Batch 2 embraces a new design language that we call digital deco. The new Passport borrows ornate elements from the art deco movement and brings them into the 21st century.

Like Passport Founder’s Edition, Batch 2 is constructed of high-quality plastic and copper-plated zinc alloy, a responsive physical keypad, and a magnetic rear cover. 

Notably, Batch 2 is almost 20% thinner than Founder’s Edition!

Battery

Batch 2 uses a standard form factor lithium-ion battery instead of AAAs. This allows for longer battery life and an accurate battery indicator.

Passport uses a standard Nokia BL-5C battery pack. This pack is readily accessible from online retailers, so you are not dependent on a proprietary Foundation battery.

Charging occurs via a power-only USB-C port on Passport. This is a special port that only has pins for power, not data, therefore preserving Passport’s airgap. No need to trust us – you can take a quick look at the port and see that most pins are missing!

Display

Passport Batch 2 incorporates a stunning, high resolution IPS color display bonded to ultra-hard glass. The display is scratch resistant and vibrant, rendering brighter and clearer QR codes in all types of lighting conditions.

The Foundation team designed an overhauled user interface to take advantage of the new display! The UI is modern yet simple, with a new left-to-right navigation.

Little Details

We are especially proud of Batch 2’s little details – like a physical power button for simplicity and convenience, and an improved microSD slot that allows the card to sit closer to Passport and eliminates the possibility of backwards insertion.

Passport now ships with new accessories. In addition to an industrial-grade microSD card and removable lithium-ion battery, Passport includes microSD adapters for iOS and Android alongside a USB-C charging cable.

We also can’t stop ogling the packaging.

Security Architecture

While Passport features an all-new design, its underlying security architecture is unchanged. Passport uses an ultra-fast STM processor, Microchip 608a secure element, Omnivision cameracube, and an avalanche noise source for entropy.

Passport’s hardware and firmware are fully open source under copyleft licenses (CERN-OHL-S and GPLv3).

Envoy

Passport is already easy to set up and pair with the software wallet of your choice, but the Foundation team wanted to take it a step further. We sought to deliver an experience that makes life easier for advanced Bitcoiners and lowers the barriers to entry for new Bitcoiners purchasing their first hardware wallet.

So we made Envoy, a mobile companion app for your Passport. Envoy performs four key functions:

  1. Helps you securely and easily set up Passport.
  2. Keeps you up-to-date with firmware updates, no computer required!
  3. Provides quick and easy access to support resources.
  4. Offers a refreshingly simple Bitcoin software wallet.
Onboarding

Envoy guides the user through unboxing Passport and setting it up securely. Instead of using our support website from your computer or phone, you’ll now be able to use the Envoy app for a much improved experience. 

Security 

Envoy primarily communicates with Passport via airgapped QR codes, ensuring that Passport is never directly connected to an online device. Initial Passport setup, supply chain validation, and Bitcoin transactions are all facilitated with QR codes. 

Passport firmware updates are securely downloaded by Envoy and transferred to Passport via microSD card. Envoy sends a push notification when a new firmware update is available, making it easier than ever to always run the latest firmware.

Privacy

Envoy connects to Foundation’s server and Bitcoin node through Tor. This means that Foundation does not know your IP address and is less able to track your activity.

For those seeking greater privacy, Envoy offers the ability to connect to your own Bitcoin node, cutting out Foundation as the middleman.

Openness 

Like all our products, Envoy is fully open source with a copyleft license (GPLv3). This means that advanced users can inspect the code, build from source, and even fork and improve the app. Envoy relies heavily on popular open source toolkits, including Flutter and BDK.

Due to Envoy’s open source nature, you can be better assured that Envoy does what we claim. You don’t have to blindly trust Foundation with the security of your Bitcoin; you can verify for yourself!

Alongside releasing Envoy in the Android and iOS app stores, we will make an APK available for advanced Android users, and will also explore releasing to the F-Droid open source app repository.

Wallet

For new Bitcoiners and those who seek a zen-like experience, Envoy offers a simple Bitcoin software wallet that automatically pairs with your Passport. 

Envoy allows you to pair multiple Passports, each with its own account to send and receive Bitcoin. The only user input is whether to “boost” your transaction by paying a higher fee – that’s it! We suspect Envoy is the simplest Bitcoin software wallet on the market.

Over time we plan to add more advanced features like coin control, but will always offer an unparalleled zen experience for new Bitcoiners.


We hope you’re as excited as we are about Passport Batch 2 and Envoy.

Passport Batch 2 is expected to ship in April. We’re beginning circuit board production later this month, and are just waiting for the plastic and metal parts to arrive. We’ll have the first set of Batch 2’s on-hand at Bitcoin 2022 in Miami next month.

Envoy will launch in app stores alongside Passport Batch 2.

Our website is now updated with all the details of Passport Batch 2 and Envoy! As Batch 2 is limited to 2500 units, we recommend preordering today to ensure availability. Please contact us with any questions via email or Telegram.

purchase PASSPORT

Order Passport Batch 2 today, limited to 2400 units!

$259.00Add to cart