Want to pay BTC at POS terminal

I guess I have to write my unencrypted private key to the NXP implanted chip? I also have my BIP38 encrypted key written to my implant which triggers mycelium.

Do I need 2 implants?

Which POS terminals support *coin keys?

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I’m going to bitcoin city Arnhem in the Netherlands. I have my implant for a year now and want to pay my coffee and groceries with bitcoin.

I have my BIP38 keys on the chip and my question is do I have to delete this and write my unencrypted private key instead to the chip or can I use both?

I cannot find any setup guide for this. So how and what do I write to the implant with NFC Tools. I see all those videos from Martijn Wismeijer but I finally want to pay myself with my implant.

Unfortunately I don’t have a clue, but my hunch is that nobody will ever suggest you write your private key to an unsecured medium, let alone share it with a payment terminal.

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I just want to fill it up with lets say 200 euro and spend some.

But what is the difference when I give a waiter my creditcard in a restaurant?

That’s such a fundamental question, it’s hard to even begin to address it.

To start, how would you pay for items with Bitcoin normally, without an implant? Describe the process.

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Thats the whole thing. I just want to know how to pay with my implant and not with my phone. I usually swipe my BIP38 wallet on the implant and transfer some btc funds to play with to my phone.

The reason I had the implant was to store my encrypted key (BIP38) and pay with btc. I cant get an answer to that one.

That’s because that’s not how it works.

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Not possible with your current implant.

How do these guys do it.

You’ll probably need the Vivokey Flex for that, I would assume. While the NeXT/xNT do allow for you to use your bitcoin key, I am not positive as to how secure that method would be. Unfortunately, the flex is currently private beta, so it would likely be very difficult for you to get one. In the video posted, my guess would be they likely be that they used their private key, which may be a solution you find to work for you, despite potential security risks.

Other example is my library card. In the card is a simple NFC chip. I’ve read the card and want to use the identifier and use it so I can identify myself.

The whole proces here in Holland lending books goes with NFC. The books also have NFC. The whole proces is automated.

So, is there a guide where I can read how to setup the implant. What I also don’t understand is can all those things be made possible with just one implant or do you need multiple implants for multiple tasks.

Why do you need a Vovokey? I can also transfer (pay) btc to my phone using the stored BIP38 encrypted private key on my implant. So if my phone can read the private key on my implant to transfer and pay with btc a bitcoin terminal must also do the same job.

Well, to be honest I haven’t played around with the NFC capabilities with BTC, nor do I have BTC to test it with. What I had meant with needing the Vivokey was due to their cryptographic functions, where there is a specific Java applet for making secure BTC transfers. However, it is likely that you could have the same effect with one of the NFC implants, just with a slightly less secure transaction (at least, thats my assumption). Its definitely worth testing if you can, maybe set up a dummy wallet and use your implant to sent it a tiny bit of money in BTC, just to see how that goes?

This is my setup:

Reading comments and going to the site of the terminal manufacturer, they do indeed store the private key on an NFC tag. This is incredibly dumb and completely defeats the purpose of public key encryption. While I understand the convenience and cool factor for it, I would not load any wallet that you store on the tag with more than you are willing to lose.



I would gladly give you my BIP38 private key. If you manage to somehow scan my implant the next step would be to decrypt the private key to be able to witdraw or spend my btc, If you can you can keep all my btc… Ofcourse I will not do so :slight_smile:

I guess you don’t understand it. What the guy on the video does is decrypting his BIP38 encrypted key so he can transfer BTC funds. The passphrase I use is 18 characters with spaces. In theory everything can be hacked but for this one you would need a quantum computer or you would have to wait a million years.

So how does the terminal decrypt the BIP38 to get to the actual wallet?

According to this, there is no way to spend money out of a paper wallet and expect to have a balance left.


Who said these terminals are using BIP38?

*coin transactions are “live” …in other words, unlike cash where you hand over something in it’s current form, the transaction itself requires computing power to complete. The implant has no computing power (this will change when the Vivokey Flex One is introduced). Since it has no computing power, it is just storage, you need an actual computer to complete the transaction. This is the only way the secure crypo part of the transaction can be completed. This computer is usually your phone as your phone can generally be trusted to handle your private keys (the “keys” to the vault that holds all your coin) and complete the crypto. But I am assuming in the case of these POS terminals using NFC, the computer is the terminal, meaning you have to share your private key with the terminal as that is the only way the transaction would be able to get complete. Once you share that, all bets are off. The purpose of public key encryption is specifically so you can share a public key and keep your private keys private. As soon as you share your private key, you have defeated that security.

Because the (yet to be released) Flex One is a javacard platform, it can perform the necessary encryption needed to complete the transactions right on the chip without compromising your private keys.

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You can write whatever you want to your implant. I don’t think you’ll get an answer about writing private keys here because most people understand the security implications.

The real question is whether whatever is reading the tag is capable of scanning through multiple NFC records to find the one it wants. For that you’ll have to ask the makers of the software/hardware that you plan to use. Many systems assume that the record it wants is the first NFC record on the tag in which case you will need two tags.