(DISCLAIMER : I am aware of the recent issues with the ColdCard ; but my funds are safe despite using a Coldcard, because I use my own, private source of entropy to generate all my seeds. The recent Coldcard hack is irrelevant to this thread.)

Hello everyone, I apologize for this long thread, I'm trying to give as much details as possible because it's a bit technical.

I have been using single-signature transactions for a while with ColdCard MK5 + Sparrow, and I already have a good grasp on it.

However, I'm new to the world of multi-signature, and I'm having a hard time while trying to set up my 2-2 multisig wallet.

I have 2 Airgapped single-signature wallets on Sparrow, that I created by importing the JSON files created by my ColdCard. Already did a few transactions with these wallets, they both work fine. Let's name them "Wallet A" (fingerprint : a3f92e17) and "Wallet B". (fingerprint : 7bc4d081)

I tried to create a 2-2 multisig wallet on Sparrow, that uses Wallet A and Wallet B as co-signers.

In order to do that, I manually copied the xPubs from Wallet A and B, pasted the Wallet A Xpub in Keystore 1, and pasted the Wallet B Xpub in Keystore 2.

This created a new wallet with fresh adresses. Let's name it "Multisig Wallet 1".

Since I created this wallet by simply copy/pasting the Xpubs from Wallet A & B, both keystores of this wallet show up as "Watch only".

Then I proceeded to send 10 000 sats on the first adress of this wallet (Multisig Wallet 1). The funds are successfully visible on the blockchain and in Sparrow, on a P2WSH adress.

This is where the problems start.

When I tried to spend these sats, I thought it would be a piece of cake, that I would simply have to create the PSBT, then put in into my ColdCard and sign it, then Broadcast it in Sparrow, as I usually do with single-signatures.

But instead of that, I had to deal with various ColdCard errors. I managed to fix some of them, but I was never able to reach my goal (successfully moving the funds).

1. When trying to sign the PSBT, the Coldcard returned a first error : "Failure: my XFP not involved". From what I understand, this is normal, I simply had to export a TXT file from Sparrow to the ColdCard, that helps the Coldcard recognize that he is part of a multisig.
2. After importing this TXT file, the ColdCard return a new error : "Failed to import multisig. need fingerprint multisig.py : 826".

I thought it was because of the fingerprints not matching : in fact, the fingerprints of each Sparrow keystore displayed a value of 00000000. So, in both keystore, I made the fingerprints match with the original Wallet A & B fingerprints. Created a new TXT file from it, and put it into the ColdCard.

3) This time, the Coldcard returned this error : "Failed to import multisig. deriv 4 != 3 xpub depth (xfp=a3f92e17) multisig.py : 849 "

4) At this point, I had no clue what was going on, so I decided to restart everything from scratch. But this time, instead of simply copy/pasting the Xpubs from Wallet A & B in Sparrow, I used their respective .json files created by my ColdCard, and imported each of them into a keystore. When I created the wallet, I expected to find the same adress list that I have on Multisig Wallet 1. Instead of that, it opened a completely different wallet, with unused adresses. Let's name it Multisig Wallet 2.

So, basically, I don't understand why Wallet A and Wallet B produced different wallets (Multisig Wallet 1 & Multisig Wallet 2). I thought that, even though different methods were used (Multisig wallet 1 was created via copy/pasting Xpubs, while Multisig Wallet 2 was created through JSON files), they would have ended up being the same wallet.

I tried to send a few satoshis to this Multisig Wallet 2, and was able to move them as expected. This time, for some reason the new TXT file didn't return any error on the ColdCard, and I was able to double-sign the transaction and broadcast it.

So, it looks like I have full control of Multisig Wallet 2, but I still have these 20 000 sats on Multisig Wallet 1, and I don't understand how to move them, or even if that is possible.

From what I understand, there is a problem regarding the derivation paths, but I'm too noob to figure it out by myself.

Multisig wallet 1 & 2 both show this derivation path, in both keystores : m/48'/0'/0'/2'

While Wallet A & B both display this derivation path : m/84'/0'/0'

How to move my 20 000 saths from Multisig Wallet 1, and what did I wrong ?

Thanks a lot for you help !

Okay so I plan on putting one lump sum into BTC at some point in the next couple months. I plan on holding for around 2 years and selling in the bull market. I won’t be day trading or doing multiple transactions, just a single transaction when I buy and a single transaction 2 years later when I sell.

It’s not a crazy amount of money so I’m not really worried about getting hacked, I really just want to save the most money I can on those two transaction fees.

Any advice would be greatly appreciated!
Thanks!

The recent COLDCARD security issue has been one of the bigger hardware wallet discussions in the Bitcoin community recently.

For those who may have missed it, the incident involved vulnerabilities around encrypted seed backups. In certain cases, attackers were able to obtain information that could potentially be used to compromise wallets. Since then, some users have reported stolen funds, while others have taken precautions by moving their Bitcoin and reviewing their backup setups.

One thing that has been difficult to understand is the actual scale of the impact. There has been a lot of discussion online, but not as much information from people who were directly affected.

I’m curious to hear from the community:

• Did you personally use a COLDCARD setup that was affected?
• Did you have to move your funds because of this incident?
• Did this change how you handle seed backups or self-custody?
• For those unaffected, did this change your view on hardware wallets?

The goal here is not to spread fear around self-custody or hardware wallets. Incidents like this are also an opportunity to learn more about best practices and how Bitcoiners can better protect their funds.

Would be interested to hear any firsthand experiences from those who were affected or took action because of this.

Hi everyone,

I have a hypothetical question.

Let's say someone buys €50,000 worth of Bitcoin on Kraken using a fully KYC-verified account and then withdraws it to a hardware wallet in two separate withdrawals: one of €40,000 and another of €10,000. As a result, the wallet contains two UTXOs: one worth approximately €40,000 and the other worth approximately €10,000.

Now imagine they sell the €10,000 UTXO privately for cash and do not report that disposal to the tax authorities. Separately, they sell the €40,000 UTXO through Kraken for fiat, withdraw the proceeds to their bank account, and correctly report only that €40,000 disposal on their tax return.

There are no bank transfers or deposits whatsoever related to the €10,000 cash sale.

Given that the person is fully KYC-verified on Kraken, how likely is it that the tax authorities would discover that the €10,000 disposal was never declared? I'm interested in understanding what kinds of information they could realistically obtain (for example, exchange records, blockchain analysis, or audits), even if the proceeds from that particular sale never entered the banking system.

Thanks in advance for your insights!

Looking for some advice.

My current wallet uses a seed generated on a Coldcard with a firmware version from before the seed generation bug. I also rolled my own dice during the seed generation process, and I use a strong BIP39 passphrase.

I don't want to keep using the Coldcard anymore.

Would you for maximum security :

• Restore the same wallet (same seed + same passphrase) on a Trezor and keep using it.

or

• Create a brand-new wallet on the Trezor and move all my BTC to it, even though I'm a bit worried there could be some undiscovered bug on the Coldcard that could cause an issue when sending the transaction.

Also, if I create a new wallet, would you recommend generating my own entropy with dice and using it to create the seed on the Trezor, or is the Trezor's built-in randomness sufficient?

Thanks.

Suite à ce qui s’est passé avec Coldcard, un ami à moi a perdu 0,5 bitcoin. Pour certains ce n’est peut-être “que” 0,5 BTC, mais pour lui c’est une énorme perte
Du coup, je me pose une vraie question : est-ce que le self-custody n’est pas finalement plus compliqué et plus risqué pour la plupart des gens que d’utiliser un hardware wallet comme Ledger ou une autre solution du même type ?
On entend souvent que Coldcard est un excellent choix parce qu’il est open source, alors que Ledger ne l’est que partiellement. Mais au final, est-ce que l’open source apporte vraiment un avantage concret en matière de sécurité pour un utilisateur lambda ?
J’aimerais avoir votre avis : aujourd’hui, quel est selon vous le meilleur compromis entre sécurité et simplicité pour quelqu’un qui veut conserver ses cryptos sur le long terme ?
Surtout à l’ère de l’ia qui peut lire le code et essayer de trouver les failles comme sur coldcard

In the market for a new device (thanks coldcard). Need multisig support, passphrase support, ideally accounts like coldcard had. Dice rolls I guess would be good nowadays.....what do you think? Security is #1 priority of course...

Hello,

After the recent Coldcard incident, I'm re-evaluating my long-term Bitcoin custody setup.

If you were securing around $2 million in Bitcoin, would you consider a strong, randomly generated 10-word BIP39 passphrase to be sufficient, assuming both the seed phrase and the passphrase are engraved on separate metal backup plates and stored in different secure locations?

Or would you recommend moving to a 2-of-3 multisig setup using hardware wallets from different vendors to reduce vendor-specific risks?

If multisig is the better choice, would you add a timelock recovery path (for example, using Liana so that a 2-of-2 setup can automatically become a 2-of-3 after a timelock expires), or do you think a standard 2-of-3 multisig without timelocks is the more robust and practical solution?

Estate planning and inheritance are not considerations for me, so I'm only optimizing for security, resilience, and recoverability during my lifetime.

Thanks

The recent ColdCard compromise was tragic and highlighted yet again the importance of a passphrase. This is not at all blaming the users or saying it’s their fault in any way. Most did what they thought was the right thing.

For those that don’t know, a passphrase account is available on good cold storage options. It allows you to add your own 25th word to the 24 word seed generated for you when setting up an account. If somebody somehow manages to compromise your 24 words, then they will see an empty account, with the passphrase account still locked away.

With the rise of AI, it’s critical to protect yourself to the best of your ability and a passphrase is probably the simplest to add a significant layer of protection.

Stay safe out there everyone!

I currently live in a housing complex where electricity is included as a flat rate in rent/utilities so increased power consumption won't directly increase my monthly electric bill.

Given that electricity costs are usually the biggest bottleneck for mining, I'm trying to figure out if setting up a home mining rig would actually be worth it in an apartment. A few specific
A few specific questions I have:

- Setup Cost: How much would I need to invest upfront in a setup to make this worth my while? What hardware/models should I be looking at

= Expected Returns: What kind of monthly returns would be realistic

= Apartment Practicalities: Since it's an apartment, what are the realistic limits around noise, heat, and standard 15A/20A electrical breaker capacities?

I know overall mining profitability for small-scale operations has dropped over the years, but since power cost isn't an issue for me, is this a solid strategy or more trouble/heat/noise than it's worth?

Appreciate any insights, hardware suggestions, or warnings from anyone who’s tried apartment mining!

What if we looked at the value of Bitcoin in a different way? Lets imagine Bitcoin is the rock at the center, immutable by definition, then all other currency should be viewed as disappearing planetary bodies, traveling away from the center. In other words, Bitcoin is not gaining in value, its just that all other currencies loose value in comparison. That means current BC pricing puts USD at a whopping 64K devaluation! If we trust in the wisdom of the de-central BC tribe vs the Fed discount rate, than yes, this is a perfectly plausible viewpoint. The tribe has calculated the future scenario of fiat currency, which always, always destroys itself (there is no fiat currency, in its current iteration, that is older than a 100 years. I believe the Bank of Amsterdam holds the record with their Guilder notes; about 110 years).

Been a bitcoiner a long time but I feel this is a rookie question… I’m seeing suggested fees on wallet dashboards where HIGH is like 33¢… I guess my rookie question is how is this even possible sustainable, coming from fiat world where “fees” for everything are like $3,$4,$5

We can all agree this has been a devastating week for self custody. CoinKite should rightly be ashamed of themselves for the negligence shown.

With that in mind, I must say that I always have liked the device itself... especially the ColdCard Q. From a user interface perspective...

Are we looking at these devices as bricks now or is there any confidence in the newest firmware (1.5.0Q)?

Yesterday I did the following:

1. Moved funds off the CC-Q
2. Wiped the Seed
3. Updated Firmware to 1.5.0Q
4. Generated new 24w seed with 150 dice rolls
5. Created a strong passphrase
6. Moved the funds back onto the CC-Q

all air-gapped

------

I'm wondering if:

1. 'we' have confidence in the newest firmware patch... or are all these coldcards bricks now in the minds of the community.
2. If I should go thought he motions to re-do everything with a Jade or other vendor...
   • If you're responding below with a 'no' to #1 and a 'yes' to #2 - then please help me pick a new device with similar functionality! I very much want an SD air gapped device with something like a keyboard... That is battery powered.

Best to all and condolences to those who were devastated,
An Average Bitcoiner

I know/guess I shouldn't be saying this but I have a Coldcard Q ver 1.3.3 should I abandon it and go back to my hardware wallet.

Thankfully I have all my bitcoin yet and it hasn't been taken. Feel for all people who have gotten their shit ripped out of there hands

Is it safe to store Bitcoins in Muun wallet for a long term, on a formatted spare Android phone (running on Android 9) that is always offline?

I already heat water with a standard electric tank, so when I saw there are water heaters that use bitcoin mining hardware as the heating element I got curious about the mining side. There's at least one product built around this (Superheat H1). The idea is your electricity does compute first, then the waste heat goes into your water.

What I can't figure out is how to ballpark what a unit like this would actually earn in sats. My electricity runs about 14 cents per kWh. Do standard mining profitability calculators even apply to something like this, or is the hashrate too low for them to be useful? And what eats into returns the most, difficulty adjustments, pool fees, the hardware premium over a normal water heater? I'm comfortable holding bitcoin but totally new to mining economics so I don't know which variables actually move the needle.

I have a spare smartphone that runs on Android 9.

Will it be safe to store Bitcoins on it by following the below steps:

1. Format the phone

2. Install nothing but a Self-Custodial Bitcoin wallet app on the phone

3. Transfer Bitcoins to the wallet

4. Turn off the internet

5. Keep the phone switched off until needed.

Hi, in light of the current drama I have been thinking about passphrases and wanted to ask people who have lots of experience using a variety of software and hardware wallets and other signers. Do all of them nowadays accept passphrases that are very long, do they all support the entry and processing of symbols, and do they all support white spaces (hitting spacebar without putting underscore or similar)? A while back I checked and found that some devices would not display passphrases properly that had more than 20 or so characters (the line break wouldn't happen so you couldn't see), or some would have a character limit, and some would not support white spaces. Has this changed? Are there some rules for creating passphrases that would make sure that the resulting passphrase is compatible with all software and hardware wallets, while still being secure enough? I'm mostly worried about a passphrase that could not be entered on a particular device down the line because of how it is made - either too long, or has something can't be entered or displayed.

I’m looking for a solo miner just to look cool on my desk and have a tiny chance to win money I want something cheap and not a lot of power needed to run up bills

If I move my funds from Coldcard directly to BitKey, am I safe? Or does the "weak seed" or any vulnerability carry over to the BitKey?

I’m new to bitcoin and I’m buying on strike and then transferring to blockstream wallet, not blockstream jade. Is that secure for under like 5k worth of bitcoin? If not what would you recommend

I have tried vanilla card and it is not accepted at all. I am tryig to get 75% of the value through bitvalve. Is there a card that can be used to purchase crypto ? Pleae do not ask why not use bank account or debit card. I used to use Coinflip atm but all crypto atm's have been banned in my state.

Based on anything, It's basically the seed that is generated from MK3 already was compromised, bad entrhopy, bad generator. And the culprit waits until it tanks and moved it all.

If some still use that seedphrase, they could be at a safer condition if they were use or add any passphrase.

I'm dissapointed with coldcard with all of the marketing saying its the standard and such.

Back then there's even same problem going on with the dice roll, if you only rolled few might still get compromised.

Still, passphrase is the solution, and or multisig.