Blockstream Green BTC wallet - can't generate seed while offline?

[ovcijisir]

Unfortunately now I will stick to this seed I generated few days ago on BlueWallet app, because I already made cryptosteel backup and generated 15 addresses on Tails OS.

ovcijisir, it was better to save your master public key.
Now, if you need more addresses, you will have to use your seed phrase again. Instead, you could save your master public key and generate any number of addresses you want from that without using your seed phrase.

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Great I didn't know that option like this exist. For now 15 addresses that I already generated will be enough but this is good option to have in mind, thanks!

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There is another interesting open source wallet app that is created to work air-gapped, and you can consider checking it out.
This is Cupcake app created to work with Bitcoin and Monero, and it can also be connected with some hardware wallets or Cake wallet:
https://blog.cakewallet.com/air-gapped-privacy-made-easy-meet-the-new-cupcake-experience/

Thanks for info! I just installed this wallet, it made no problems generating seed while offline. Only potential problem could be that ot doesn't use BIP 44 derivation path, so I'm not sure if it is compatible with other wallets.

I wanted to make the seed for long term storage and there is possibility that developers of Cake wallet stop developing this project in (far) future. That is why I wanted to use BIP 39 / BIP 44 wallet and didn't use Electrum running on Tails OS to generate seed. I wanted most standard seed that can be recreated on many different wallets. The more standard solution the less problems it will be to use the funds in 10, 20 or more years.

[Charles-Tim]

Thanks for info! I just installed this wallet, it made no problems generating seed while offline. Only potential problem could be that ot doesn't use BIP 44 derivation path, so I'm not sure if it is compatible with other wallets.

It is using BIP39 seed phrase. That is all that matters. You can be able to recover your coins on other wallets.

The wallet is also supporting Electrum seed phrase if you wish to go for that option. But you posted that you wanted universal one which is BIP39 and it is also supporting it.

I tested the wallet few weeks ago and I added it here.

[Pmalek]

@ovcijisir
Here is my experience when trying to create wallets on airplane mode on Blocksktream Green and Blue Wallet.

Blockstream Green:
The app asked for my biometrics (fingerprint) at the beginning of the setup process. I had two options: to provide it by touching my fingerprint sensor or click the "Cancel" button. I clicked cancel and entered a 6-digit PIN code instead. The software started creating the wallet but it failed and I saw the "Network error" message you mentioned. I tried two more times and got the same error.

Then I went back to the beginning and provided my biometric data. Blockstream Green generated the wallet immediately. So, if the software gives you the option to provide your biometrics to unlock it, you should provide it. That's what worked for me.

Blue Wallet:
I had no issues logging in to my existing Blue Wallet app and generate a new wallet and seed in airplane mode. It shows a syncing notification that doesn't go away but that's normal since the app doesn't have internet connection and can't connect to a server.

[ovcijisir]

@ovcijisir
Here is my experience when trying to create wallets on airplane mode on Blocksktream Green and Blue Wallet.

Blockstream Green:
The app asked for my biometrics (fingerprint) at the beginning of the setup process. I had two options: to provide it by touching my fingerprint sensor or click the "Cancel" button. I clicked cancel and entered a 6-digit PIN code instead. The software started creating the wallet but it failed and I saw the "Network error" message you mentioned. I tried two more times and got the same error.

Then I went back to the beginning and provided my biometric data. Blockstream Green generated the wallet immediately. So, if the software gives you the option to provide your biometrics to unlock it, you should provide it. That's what worked for me.

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Thank you for feedback Pmalek! I never share biometric data, so that is almost certainly the cause of my issues. I was wondering why other people could generate wallet offline without any problems while I couldn't.

Ill try to generate new wallet with biometric data allowed on another phone later and send feedback regarding results.

[Charles-Tim]

Then I went back to the beginning and provided my biometric data. Blockstream Green generated the wallet immediately. So, if the software gives you the option to provide your biometrics to unlock it, you should provide it. That's what worked for me.

I did not even know the wallet can still give password pin option except going to settings to do it, but because of your post, I clicked on 'cancel' which is beside the fingerprint and it brought up password pin. I used the password pin and it did not generate the wallet.

[Pmalek]

Thank you for feedback Pmalek! I never share biometric data, so that is almost certainly the cause of my issues. I was wondering why other people could generate wallet offline without any problems while I couldn't.

They probably didn't even consider that part crucial to the wallet creation process. I don't know why it matters either. I see no reason why I shouldn't be able to generate a new seed offline if I use PIN as my security instead of biometrics. It's not a protocol-level requirement. It's a weird decision made by Blockstream or maybe even an oversight or bug on their end.

I did not even know the wallet can still give password option except going to settings to do it, but because of your post, I clicked on 'close' which is beside the fingerprint and it brought up password. I used the password and it did not generate the wallet.

Password or PIN? I only saw biometrics or PIN codes, but not passwords.

[Charles-Tim]

Password or PIN? I only saw biometrics or PIN codes, but not passwords.

Do not mind me. It is pin, not password.

[ovcijisir]

Thank you for feedback Pmalek! I never share biometric data, so that is almost certainly the cause of my issues. I was wondering why other people could generate wallet offline without any problems while I couldn't.

They probably didn't even consider that part crucial to the wallet creation process. I don't know why it matters either. I see no reason why I shouldn't be able to generate a new seed offline if I use PIN as my security instead of biometrics. It's not a protocol-level requirement. It's a weird decision made by Blockstream or maybe even an oversight or bug on their end.

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Earlier today I tried to install fresh copy of Blockstream Green to generate new seed, but I didn't get option to share biometric data.

I never did set up any biometric data on that phone (fingerprint sensor nor face unlock) so that could be the reason why Blockstream Green didn't ask me to share biometric data, because there were not any in the first place.

After that I did factory reset on phone again, and this time I did set up fingerprint sensor. After downloading and installing Green wallet I turned off wifi, bluetooth and went into airplane mode. This time Green asked me to share biometric data, which I did, and after that there was no problem generating new wallet.

Usually I'm not comfortable sharing my biometric data, as it could leak who knows where, but in this case I was too curious to see if it will work and it did.

[Pmalek]

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I will see if I can get in touch with the Blockstream support team and ask them why their native software requires biometric data to generate a seed offline and at the same time refuses to create a new wallet if you choose to access the wallet with a PIN. There should be no reason for that. Also, what about older phones and those that don't have a fingerprint sensor? That would then mean that they can't generate a new seed without internet connection.

[ovcijisir]

<Snip>

I will see if I can get in touch with the Blockstream support team and ask them why their native software requires biometric data to generate a seed offline and at the same time refuses to create a new wallet if you choose to access the wallet with a PIN. There should be no reason for that. Also, what about older phones and those that don't have a fingerprint sensor? That would then mean that they can't generate a new seed without internet connection.

Thank you Pmalek for your initiative, it would be great to have it fixed if it is bug, or at least to have some information why it is needed if they make it like this on purpose. It would be great if you would share information when you get feedback from them 

[Pmalek]

Thank you Pmalek for your initiative, it would be great to have it fixed if it is bug, or at least to have some information why it is needed if they make it like this on purpose. It would be great if you would share information when you get feedback from them 

The Blockstream support team replied back to me and it's not a bug. They made it that way on purpose.

They say it's a security design. PIN-based logins take advantage of Blockstream's blind oracle security model. Essentially, it's a remote server. When you use PIN logins, the application communicates with the blind oracle that holds a piece of your wallet's encryption key and retrieves that piece of data. The combination of the two is needed to unlock your wallet. They say that this design prevents someone from accessing your wallet and stealing from your app by just knowing your PIN and having physical access to your phone.

But if you use biometric logins, then the encryption and decryption takes place in your device's operating system. It doesn't require access to the blind oracle to retrieve a part of the encryption key. Everything is done locally on the device. That's also why you can generate a seed when offline.

[ovcijisir]

Thank you Pmalek for your initiative, it would be great to have it fixed if it is bug, or at least to have some information why it is needed if they make it like this on purpose. It would be great if you would share information when you get feedback from them  

The Blockstream support team replied back to me and it's not a bug. They made it that way on purpose.

They say it's a security design. PIN-based logins take advantage of Blockstream's blind oracle security model. Essentially, it's a remote server. When you use PIN logins, the application communicates with the blind oracle that holds a piece of your wallet's encryption key and retrieves that piece of data. The combination of the two is needed to unlock your wallet. They say that this design prevents someone from accessing your wallet and stealing from your app by just knowing your PIN and having physical access to your phone.

But if you use biometric logins, then the encryption and decryption takes place in your device's operating system. It doesn't require access to the blind oracle to retrieve a part of the encryption key. Everything is done locally on the device. That's also why you can generate a seed when offline.

Thank you for your effort Pmalek. To be honest that security method doesn't makes sense to me, because if someone has physical acces to the phone and knows PIN, he can just enter PIN in app he will have access to the decrypted wallet just the same like if decryption without blund oracle wouldn't take place ...

I am not very educated in computers but it just isn't logical to me

But it is nice to know that they did that solution by design and not by accident.

[Pmalek]

To be honest that security method doesn't makes sense to me, because if someone has physical acces to the phone and knows PIN, he can just enter PIN in app he will have access to the decrypted wallet just the same like if decryption without blund oracle wouldn't take place ...

I am not very educated in computers but it just isn't logical to me

I understand what you are saying. To be honest, I am confused with their answer as well. I have asked them more questions after their initial reply. I will share here what they say if it's something worth adding. They seem to have confused using the Blockstream app as a companion app to the Jade with creating a hot wallet on the software. I have asked them how the interaction with the blind oracle will prevent a malicious third party who knows the PIN of the wallet from accessing it and stealing the coins. The software can't differentiate between me and you to know who is the legitimate owner and who is trying to steal from someone else's wallet. 

[ovcijisir]

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I understand what you are saying. To be honest, I am confused with their answer as well. I have asked them more questions after their initial reply. I will share here what they say if it's something worth adding. They seem to have confused using the Blockstream app as a companion app to the Jade with creating a hot wallet on the software. I have asked them how the interaction with the blind oracle will prevent a malicious third party who knows the PIN of the wallet from accessing it and stealing the coins. The software can't differentiate between me and you to know who is the legitimate owner and who is trying to steal from someone else's wallet. 

From what you mentioned, it seems to me PIN function is tightly tied to Jade wallet, maybe that is the reason why Blockstream Green can't generate seed offline. Maybe it would interfere with Jade wallet functionality.
This is only my wild guess, lets wait to hear from Blockstream...