I have been using Casa Keymaster 2 of 3 setup without any problems.

I have been using their service and I haven't had any problems.

I have been using their service and I haven't had any problems.

Gemini officially announced its partnership with Samsung Blockchain Wallet.

https://gemini.com/samsung

Your S10 should already have Samsung Blockchain Keystore depending on your country.

Yeah, Samsung states they don't store your private keys and it is up to you to keep your seed phrase safe. I haven't had any problems and I have been using it for 8 months now. I'll report back here if I run into any problems with their wallet.

I sent some bitcoin out of my Safepal wallet last weekend and everything went fine. I did notice the QR codes it creates is encrypted, so only the Safepal app knows what I'm transmitting. Also, since I didn't use the wallet for 5 months, I had to recharge it before using it. I also upgraded the firmware from an offline device before sending some bitcoin out of it.

According to the Safepal app, the remaining bitcoin in the wallet is still there. So everything is still good. I'll come back here in the future and post anything suspicious from using the wallet.

That might be an issue. I think you have to sign in with your Samsung Account on the phone in order to use the hot hardware wallet. I guess this would mean the wallet and your Samsung Account could be linked together in some way.

The phone comes with a separate hardware chip inside. The Samsung Blockchain Keystore is part of the OS, not a separate app you can download or delete. This controls the hardware chip. The Samsung Blockchain Wallet app I think might have come pre-installed, but you can download it from the Samsung Galaxy Store (it is not on the Google Play Store). You can download the APK from other sites though, but I would only get it from Samsung.

Samsung's Blockchain SDK hints at being able to connect to a Ledger with an OTG cable, but I don't know if that has been developed yet.

Yeah, I know. I just wanted to make it easier for the non-tech people around me. It is a pretty slick little device and I did update the firmware only once when I got it. I used an online device to download the firmware and then I copied the file to a airgapped device and then connected the wallet to the airgapped device to copy the file to the wallet. Then I installed the update via the wallet interface after disconnecting from the airgapped device. This might be a little overkill, but it was fun.

Shoot, I didn't even let the device create the wallet for me since I restored an existing wallet, all while offline. I do have one disclaimer though, I have only sent bitcoin to it and I have not used the wallet to send any bitcoin. I guess if all of my bitcoin disappears after I send some, then I'll know this wallet isn't any good. The only way that I could think that could happen though, is when I'm am scanning the QR code on the wallet with the Safepal app on my phone and it somehow transmits my seedphrase/private keys through the QR code to the app and sends it to hacker.

But shouldn't I be able to scan the QR code with a different device to see what it is transmitting and be able to see if it is transmitting my seedphrase?

It's definitely not a rumor. It is on both of my Note 10+ and S10e. The private keys are stored in a separate chip that only the Samsung Blockchain Keystore app can access. Once you get the Keystore security setup, you can then let it create the wallet seedphrase for you or you can import your own (per BIP39). The Samsung Blockchain Wallet is the app interface you use to manage your bitcoin. It gives 3 suggested transaction fees based on transaction time, but you can set a custom fee if you want to. It uses SegWit addresses (not native SwegWit, but you can send to them). They do allow you to store alt coins, but I only use bitcoin and it works pretty good. Here is their promo page for this feature https://www.samsung.com/global/galaxy/apps/samsung-blockchain/ They also have a website for developers with their Samsung Blockchain SDK.

I use this wallet and I have not had any problems. This hardware wallet might be my favorite out of all of my hardware wallets. I do not own a Ledger or Trezor though, as I prefer all of my hardware wallets to never be connected to a device while the device is connected to the internet.

I use the Samsung Blockchain Wallet and I never had any problems.

I tried out this wallet and it definitely looks good so far.

I did notice there is a "withdraw from wallet" fee of about 0.1%. Is that correct? I assume this is part of the business model as the app is free and it is free to deposit into the wallet, but there is a cost to withdraw.

Using an android device for the cold wallet seems pretty secure to me by using the following workflow:

1. factory reset android device
2. add google account to device (If I remember correctly, if using 2FA with the google account, you will need to enter this code as well when adding your account to the device)
3. add a unique password to the startup of the device or when the device is locked
4. turn on wifi and connect to your own wifi
5. download app from play store
6. turn off wifi and forget wifi connection
7. run app and create a wallet with your own entropy or restore your wallet
8. add unique password to the app
9. use wallet normally
10. if the app is updated, then start at step 1

One thing I am not sure of though:

When I want to send BTC to another wallet and I am using the selftrust.me website, how do I know the app on the cold wallet phone is not sending the seedphrase/private keys to the selftrust.me website to be stored? This could be just an inherent limitation of wallets in general as we will always have to trust the wallet/seed generator to some extent, just as I have to trust in the full node I am running.

It would be nice if I could specify my full node for this wallet.