Topic: Quick advice for making secure private and public bitcoin keys for micro QR code (Read 193 times)

the hard part is not knowing what wallet the recipient will use - if they use Bitcoin Core, it will not matter what format the address is. Some wallets can be picky that is true - some you have to tell it what type the address is for that specific key - for example, with Electrum if the address begins with "3" you will need to prepend “p2wpkh-p2sh:” to the private key when importing it and if the address begins with "bc1" then you will need to prepend “p2wpkh:” to the private key when importing it.

So, I finally did some testing with Bitkey.io but found that since its been a couple years, the wallet apps are quite old now.  Not a lot of options for making segwit addresses, but there was a wallet made by coinb.in that allowed me to make segwit (type 3 addresses), so I made some public and private keys offline with that and then tested sending to it and redeeming with the private key later.

During this testing phase, I needed a phone app wallet so I installed Exodus wallet and when I scanned my private key it said "No funds found in key", and when I contacted their support they said that they only support legacy and segwit (bc1 type) addresses.   So, now I'm rethinking whether it's smart to use type 3 segwit addresses.  Maybe I should just stick with bc1 since its the newest and the transaction costs should be less than legacy.  FYI, I tested the private key with a mycelium wallet and was able to sweep the private key and move it to that new wallet.

I also wish I could find a better offline solution that allows me to create segwit bc1 addresses.  I could turn off wifi on my windows laptop, make them all offline, and then wipe my drive fully I suppose, but if I screw up half-way and need to get online I would need to wipe it first.  Maybe a dual boot into a new linux system would be good.

Good points: nobody has reported any bug/backdoor, 0 scam reports, Open-source project, and running from a long time.
Bad points: The code has not been updated for a long time, so there may be some bugs, I suggest that you do not use it in large sums.

bc1 addresses is the best, but many platforms do not support it.
I suggest you use P2SH^[1] type starting with the number (3.)


[1] https://en.bitcoin.it/wiki/Pay_to_script_hash

not a problem, I don't mind helping at all.

I'm working on the artwork for the opposite side of the chip now.  I might get into the weeds with the wallet/keys next week, so I'll follow up later on. Thanks!

yes but the text you have to type is "dumpprivkey" followed by the public address

if the core version you are using created that address then you "own" that key and it will display it.

if you try that with a public address that you do not own, it will not work.


edit:

if you want a visual, I am more than willing to do the process over like TeamViewer -- can create a pub address, pull the priv key and create the code --- of course this would be for an address and key that would never be used after that.

It's a little confusing, but I'm pretty sure after a few tests (and then doing it 300 times) it will make sense. 
I mean "dump"?  I had to look that up.  Maybe use the word print or display? lol...

let me use bitcoin core for example -

you hit receive and it can generate a new address.
copy the address
send funds to the address from another wallet/computer that is connected to the internet
copy the address
open console
type dumpprivkey

copy the private key
paste into the qr generator
copy the qr code/scale it to fit/attach to holo and to the chip/coin/wallet you are wanting to use.

that is a very simplified explanation of the process but also seems to make it look complicated maybe?

Thanks Mopar. 

I think I'll put a little QR code AND the 30ish digit private key under the holo sticker (because why not!).  And I plan on putting the public key QR code on the outside of the holo sticker since it can be a little larger.

I'll use electrum, bitcoin core or bitkey.io in the air-gapped PC and I'll do some research first to figure it out.

I know I can create the keys, but at some point it has to sync the keys to the bitcoin blockchain, right?  I mean, I'm going to fund them so can I just delete the private keys after I make them and before I connect it up to the network to sync?  I don't really get that part of it. 

I have never used or heard of bitkey.io --- and I will preface that I am not expert by any means, I am simply relaying my experience in doing something similar to what you are doing. I will also say with the dozens that I have made that not one of the ones I have generated have been breached or had funds stolen.

I have created private keys using vanity gen on an airgapped pc that has never been online - downloaded the program to a usb drive and installed on the laptop.

can read about it and download it directly from here: https://en.bitcoin.it/wiki/Vanitygen but that was also to create vanity addresses at the same time.

if you dont need vanity addresses, you can simply use bitcoin core to generate a new address and a new private key with it.

that is a very simple process to do in bitcoin core. or even in electrum if you do not want to download the all the block history.

as for the holograms and qr codes - I have done that to dozens of chips/coins. and as small or very close to what you are suggesting - I use a browser plug in on the same air gapped pc (yes it is a brave browser extension but does not need to be online) every program I install on the airgapped pc is done via a usb drive to convert those private keys into qr codes.

as for that "mini key" i think you are referring to "firstbits" that usually references the public address - can read more about it here. https://en.bitcoin.it/wiki/Firstbits

see pictures for one of them I did for my personal vanity gen address -- the private key is a qr code under the holo on the rear, the paper in front of the slab has the public address as typed and as a qr code.





if you want more information - please feel free to pm me or to ask here.

I was told by a Sr member that this was the best forum area to get the most exposure for my question. 
I don't need all the details, just some general advice (links or even just the correct words/terms so that I can Google this all myself and find what I'm looking for:

I need to make:
Very secure bitcoin private/public keys generated (preferably offline or air-gapped). 
I'm looking at using this:  https://bitkey.io/   
Can anyone vouch for it? 

Once I have my keys, I need to be able to print them out as micro QR codes (or whatever it's called) so that I can fit it under a 1 inch circular hologram sticker with plenty of space along the sides for the tamper-evident portion to leave its mark if removed.  So the QR code would be like 10-12 mm at most.  Is there such a thing as a mini key that takes up less space for that?  I'm pretty sure I've seen it on other physical bitcoins...

Should I use legacy or segwit keys? 

I'm not sure how to get the private key to turn into a QR code, but I also haven't played with bitkey.io yet, so I might just figure that out later on.

Thanks in advance!