Topic: ColdCard hardware wallet (Read 2463 times)

ColdCard Mk4 is now available for purchase directly, without reservations and extra waiting time.
Price is around $158 plus shipping, but I think you can get free shipping if you spend $499 or more in Coinkite shop.
There is %5 discount with promo code CKBTC, and it would be interesting to see some independent reviews for this new mk4 Coldcard.
I think there are better hardware wallets than Coldcard Mk4 in market today for this price, but others like ledger or safepal are worse and inferior in my opinion.
https://store.coinkite.com/store/mk4

Thank you for posting this update nvK.
We had to speculate a bit how everything works with two secure elements, and you guys didn't exactly released any documentations until recently.
Can you tell us the reason why exactly did you chose second secure element model Maxim DS28C36B instead of other alternative options?

From what I see this Maxim DS28C36B is Secure Authenticator mostly used in equipment like:

- IP Protection
- Medical Consumable ID
- Medical Sensor Authentication and Calibration
- PCB ID and Authentication
- Print Cartridge Authentication
- Printer Cartridge Configuration and Monitoring
- Rack Card Security
Source:
https://www.maximintegrated.com/en/products/embedded-security/secure-authenticators/DS28C36.html

Beware!
I don't remember that I saw anyone posting this before, but if you already own ColdCard Mk3 hardware wallet you may want to check this out.
This was first posted on twitter by LazyNinja and it reveal big security flaw with ColdCard Mk3 PIN Replacement Attack.
He was able to bypass MK3 security feature and after second attack he was able to perform seed extraction from ColdCard device (passphrase was not extracted).
If you are using Bootloader v2.0.0 or older than you are vulnerable to this attack, due to flaw in Mk3 architecture discovered by LazyNinja, that enabled PIN replacement.
This was later fixed by ColdCard developers but you can't fix it yourself if you already own this device.
Maybe this was the main reason for ColdCard decision to release Mk4 device with two secure elements, but I someone will try to find flaws in that system as well.


More details with videos:
https://threadreaderapp.com/thread/1377362927729082368.html

Solution for anyone who owns Mk3 device is to add mandatory passphrase and move funds to new address or use some other better hardware wallet.
I have to say that I don't trust this new invention from ColdCard and they are only hardware wallet with secure element that got hacked, that is bad advertisment.

Uhhhh -->You<-- posted it before.....in this thread...about a year ago.
Things we learned today....dkbit98 is an true American and was drinking way to much at the Memorial Day BBQ and erased the last year of his memories.

Beware!
I don't remember that I saw anyone posting this before, but if you already own ColdCard Mk3 hardware wallet you may want to check this out.
This was first posted on twitter by LazyNinja and it reveal big security flaw with ColdCard Mk3 PIN Replacement Attack.
He was able to bypass MK3 security feature and after second attack he was able to perform seed extraction from ColdCard device (passphrase was not extracted).
If you are using Bootloader v2.0.0 or older than you are vulnerable to this attack, due to flaw in Mk3 architecture discovered by LazyNinja, that enabled PIN replacement.
This was later fixed by ColdCard developers but you can't fix it yourself if you already own this device.
Maybe this was the main reason for ColdCard decision to release Mk4 device with two secure elements, but I someone will try to find flaws in that system as well.


More details with videos:
https://threadreaderapp.com/thread/1377362927729082368.html

Solution for anyone who owns Mk3 device is to add mandatory passphrase and move funds to new address or use some other better hardware wallet.
I have to say that I don't trust this new invention from ColdCard and they are only hardware wallet with secure element that got hacked, that is bad advertisment.

Important update for Coldcard hardware wallet and not so secure Secure Elements!

@LazyNinja managed to find a flaw in architecture and bypass ColdCard MK3 security feature by opening hardware wallet, removing secure element and replacing device PIN with his own PIN code, and then he returned altered secure element and gained full access to device.
Reminder that ColdCard is using ATECC608B secure element and this attack was possible with bootloader v2.0.0, and to fix this you need to have new updated bootloader v2.0.1

Similar pin replace attack could happen for ledger and other hardware wallet devices, but he said that hardware wallets are still 100x safer then using regular PC, however they are not invincible.

Check out his thread and video procedure:
https://threadreaderapp.com/thread/1377362927729082368.html

There is a lot of misinterpretation on the Mk4's Dual SE on this thread, I highly recommend reading these two docs:

Wonder how long they will keep the older versions going.

...
It's much easier and cheaper to return your license to open source than doing all this gimmicks.

...

There is one alternative website I found for WalletScrutiny and it is called bitcoinbinary.org, interesting part is that one of bitcointalk moderators achow101 was testing wallets and participating in this exercise,
I don't know if this website is sponsored by Coinkite aka Coldcard, but they did receive 0.025 BTC donation from them and githuib page is posted on Coinkite github,
so it looks like ColdCard wanted to proved how their code is still reproducible even if it's not open source anymore.
Conclusion is that many wallets have bad documentation or incorrect build instructions so they couldn't be reproduced.


Github: https://github.com/coinkite/bitcoinbinary.org
Website: https://bitcoinbinary.org/

Yes, but Trezor was the first hardware wallet and it's normal that many other hardware wallets are using their code, either partially or fully, disclosed or undisclosed, with or without credits, I never saw SatoshiLabs complain about that.
Coldcard probably changed original code so much or rewritten it totally in other language, so they can easily skip breaking of any rules, like they did with latest MIT+CC license.
btw. Someone tested Coldcard code and found it was reproducible, funny thing is that this website bitcoinbinary.org was started and donated by Coinkite aka Coldcard

Coldcard probably changed original code so much or rewritten it totally in other language, so they can easily skip breaking of any rules, like they did with latest MIT+CC license.
btw. Someone tested Coldcard code and found it was reproducible, funny thing is that this website bitcoinbinary.org was started and donated by Coinkite aka Coldcard

Most of Trezor code is GPLv3, right? That license states if you reuse the code, you have to keep it under GPLv3. By switching license, I think they are breaking this rule.
I agree, it's especially ironic that they themselves used Trezor code and went all pissed when Foundation Devices did the same thing. I was about to get a mk3, but the one thing always holding me back was that I'd need to carry around microSD card adapters all the time. Their understanding of open source put the final nail in the coffin for me not to buy it. It's a shame since I like the form factor and air gapping in general.

I am still disappointed they decided to switch their license from Open Source to MIT+CC.
Funny thing is they first forked original Trezor wallet code that is still Open Source, but then they switched their license when someone else (read Passport) forks their code.

...
Dude, they literally used Trezor code themselves, so I guess it's just open source karma
Forking will cause no issue on Coldcard code, same way like changes in Coldcard does not affect original Trezor code.

but even I put that warning on links I post when dealing with things that have to do with wallets and such here on the forum.

As for the forking of the code and changing the license, I am beginning to kind of, sort of, a very very little bit more take their side.

For Dave and others who are using Coldcard hardware wallet, it's time to upgrade your firmware to latest version 4.1.3.
They fixed some bugs and increased Bitcoin Core Airgap support, but I am still disappointed they decided to switch their license from Open Source to MIT+CC.
Funny thing is they first forked original Trezor wallet code that is still Open Source, but then they switched their license when someone else (read Passport) forks their code.
Now you can only read their code, but you can't contribute anything and you can't really verify and reproduce the code.
Instead they use something like this:
https://gist.github.com/xavierfiechter/0b7323318ada8937f817606dff8fdb57

Full list of changes:
https://coldcardwallet.com/docs/upgrade

Version 4.1.3 - Sept 2, 2021

- Enhancement: support "importdescriptors" command in Bitcoin Core 0.21 so that a descriptor-based wallet is created. PSBT files are then supported natively by Core, and the resulting desktop wallet can be used for spending (ie. create PSBT via GUI) and also watching. Translation: Easy air-gap PSBT operation with Bitcoin Core!
- Enhancement: remove "m/0/0" derivations from public.txt and address explorer, since that path is obsolete and not used by any major wallets now. We can still sign PSBT files with that path, but it's an unnecessary risk to show derived addresses for a type of wallet that doesn't exist anymore.
- Enhancement: if PSBT input sections don't contain the key path information we need, show a more specific error message.
- Bugfix: a PSBT which provided the wrong pubkey (based on UTXO being spent) was not flagged as invalid, but instead we proceeded to do nothing. Now says "pubkey vs. address wrong".
- Bugfix: if asked to serialize a partially-signed transaction, we did. Now fails properly.
- Bugfix: if multiple copies of the same BIP-39 passphrase were saved to a card, the menu would not display correctly and you might not be able to select your saved value.

With all the latest law propositions in US congress it's possible that they will try to outlaw or additionally tax any transactions coming from hardware wallet, so having this enhancement is a good idea coming in right time.

I am not sure how other hardware wallets like ledger and trezor are handling this issue with signatures, and I wonder is every hardware wallet have specific signature size.

Question for you @DaveF:
Is there a way to check and confirm integrity of ColdCard hardware wallet after you purchase it and receive it?
Something similar like for other hardware wallet I wrote few days ago:
https://bitcointalksearch.org/topic/check-integrity-of-hardware-wallets-5351249

Supply Chain Protections

Getting an uncompromised product into your hands is a challenge:
Bag Number

First and foremost, we use a tamper-evident plastic bag to package the product. Each bag is unique and coded with a number. That "bag number" is written into the Coldcard's secure element as it's put into that bag. That value cannot be changed, and we ask your to verify the bag number when the Coldcard is powered-up for the first time at your location.
Clear Case

The clear plastic case on Coldcard is an important feature as well. There have been demonstrations of inserting custom hardware inside a competitor's hardware wallet to capture key-presses.
Epoxy Globs of Love

We cover the secure element, and other sensitive parts of the Coldcard with epoxy. This makes it harder to remove those chips, or change the wiring around them.

GENUINE VS. CAUTION LIGHTS
To resist Evil Maids, and other sneaky people with physical access to your Coldcard, we sign our firmware with a factory key. During boot-up, the firmware's signature, and every byte of flash memory, will be verified and the appropriate Green/Red light set. Changing that light's status is actually controlled by dedicated circuitry connected directly to the Secure Element, so a rogue bit of software cannot override it. The circuit for the lights is exposed on the top surface of the product, and covered with clear epoxy, so any physical tampering by those maids will be visible as well.

Never really thought about the security implications about the fact that transactions could show that you were using a hardware wallet.
Now your TX look like you are just using the core wallet.

Version 4.1.2 - July 28, 2021

    Enhancement: Shows QR code with BIP-85 derived entropy value if you press (3) while value shown on-screen. Thanks to @opennoms for idea. Works with 12/18/24-words, XPRV, privatekey and even hex cases.
    Enhancement: Offer to show QR in other places:
        Coldcard's main XPUB, in Advanced > View Identity
        Seed words, during picking process (before the quiz)
        Stored seed words: Advanced > Danger Zone > Seed Functions > View Seed Words
        TXID of just-signed transaction (64 hex digits)
        Encryption password for the system backup file (12 words)
    Enhancement: We now grind a nonce so that our signatures are always 71 bytes or shorter. This may save a byte in transaction size, and makes our signatures identical to those produced by Bitcoin Core, improving anonymity on-chain. Thanks to @craigraw for detecting this.
    Bugfix: On a blank Coldcard, after importing a seed phrase using the Seed XOR feature, the main menu was not updated to show system is "Ready To Sign".
    Bugfix: Red caution light could happen (a false positive) if a specific sequence of firmware upgrades and reboots occured in the right order. Issue could only occur once during lifetime of any particular Coldcard.

    Enhancement: We now grind a nonce so that our signatures are always 71 bytes or shorter. This may save a byte in transaction size, and makes our signatures identical to those produced by Bitcoin Core, improving anonymity on-chain. Thanks to @craigraw for detecting this.

Hmm? The attacks bypasses the PIN and would just reveal everything. I don't think Coldcard uses passphrase as an encryption, or else it would have more than a keypad, or perhaps I haven't used it enough . Exploiting the SE is probably the most crucial part of the attack and if it succeeds, then I don't see much deterrence against physical attacks.

Well sure but someone could just take your hardware wallet, tamper with it and modify it like LazyNinja did, then return you that modified hardware wallet without you even noticing it.

I think you may be right about this, and one of the ways to mitigate this is by using good passphrase for your hardware wallet as extra layer of protection.

As I got the vulnerability may only occur after  ColdCard has been physically in the wrong hands. If you didn’t let it out of your hands nothing can happen. IMO, any wallet  that has been in the wrong hands should not be trusted, it has to be thrown away immediately.

Bootloader cannot be updated or modified after production. The bootloader was updated in June last year and for what it's worth, my ColdCard from Nov 2020 has ATECC608A so I believe they only changed the secure element recently. Bummer.

As I got the vulnerability may only occur after  ColdCard has been physically in the wrong hands. If you didn’t let it out of your hands nothing can happen. IMO, any wallet  that has been in the wrong hands should not be trusted, it has to be thrown away immediately.

Wouldn't be better for manufacturer to put a sealing compound over everything inside the wallet to prevent it from any type of  the "inside"-attack?  

Now is this fixing that or is it fixing something else?
It's a holiday weekend so lets see if they respond on Monday / Tuesday.

This update is probably not yet released for general public, and you can confirm it easily if you check the version of bootloader on your device.
I think Coldcard is working together with LazyNinja on this fix.

Now is this fixing that or is it fixing something else?

Makes you wonder how the clone (passport wallet) will handle this.

Important update for Coldcard hardware wallet and not so secure Secure Elements!

@LazyNinja managed to find a flaw in architecture and bypass ColdCard MK3 security feature by opening hardware wallet, removing secure element and replacing device PIN with his own PIN code, and then he returned altered secure element and gained full access to device.
Reminder that ColdCard is using ATECC608B secure element and this attack was possible with bootloader v2.0.0, and to fix this you need to have new updated bootloader v2.0.1

Similar pin replace attack could happen for ledger and other hardware wallet devices, but he said that hardware wallets are still 100x safer then using regular PC, however they are not invincible.

Check out his thread and video procedure:
https://threadreaderapp.com/thread/1377362927729082368.html

You may also want to test out Coldcard 4.0.0 Firmware Release update with some nice improvements and bug fixes
Interesting new thing is that there is Secure Coldcard Cloning, and you can just copy everything to your MicroSD card with encryption and restore it on a brand new or blank device.

Will test in the next week or so and report in.

Does not look like that big of an update but as always it's probably good to be running the latest firmware on anything financial related. Just my view, I could be wrong :-)

    Major Address Explorer enhancements! Thanks go to @switck for this major feature bump.
        View sub-accounts as exported, just enter the account number.
        Multisig wallet support! (Caveat: addresses are for verification purposes and never for direct use as deposit, so they are partially redacted)
        Enter any custom derivation path, by entering numbers directly; for gurus.
        Warning screen can be suppressed after reading first time (press 6)
        Export of addresses now named "addresses.csv" not ".txt"
    Bugfix: Disable a few more path derivation checks for "Skip Checks" for multisig compatibility. Handles error shown when working with previously-imported Spectre multisig wallets (ie. multisig.py: 891).
    Bugfix: Generic wallet export (JSON) name for BIP49 wallets changed from "p2wpkh-p2sh" to "p2sh-p2wpkh".

I don't think a new licence can apply to old versions of the code... you can't (or at least, you shouldn't be able to) retroactively change the rules like that. Imagine if you have a repo that people had been forking for years and then just suddenly decided "you must pay $1000 to use this code".

Anything created after the date of the licence change should be covered by the new licence... but anything that was done prior to that, should be covered by the old licence.

--snip--
They went to the CC Commons Clause license to screw with these people: https://bitcointalksearch.org/topic/thoughts-about-passport-hardware-wallet-5265233 and were public about it.
I have no problem with them changing how they do / license stuff but it should be for all work after "X" date. If I am doing something using your code that was GPLd and then you come back and change what I can do after, it's just a dick move. Now, what the Passport people did was not cool either so there is that, I just think they could have handled it a tiny bit better.

-Dave

I'm a bit confused, does that mean they change every single git commit (which means commit hash changed) to make every single commit contain current license (GPL, MIT & CC rather than only GPL)?

Removing paper wallet feature doesn't make sense, but what's wrong by using multiple license when AFAIK both MIT and CC are less restrictive than GPL?

Version 3.2.1 - Jan 8, 2021
Major Multisig improvements! If you are using multisig features, please backup your Coldcard before upgrade, just in case (but shouldn't be a problem).
Tracks derivation path for each co-signer and no longer assumes they all use a shared derivation path. Blocks multiple instances of same XFP in the wallet (not supported anymore, bad idea). Various displays updated to reflect derivation path change. Text file import: "Derivation:" line can be repeated, applies to all following xpubs.
Show Ypub/Zpub formated values from SLIP-132 when viewing details of wallet.
Standardize on "p2sh-p2wsh" nomenclature, rather than "p2wsh-p2sh", thanks to @humanumbrella. For airgaped multisig wallet creation, you must use same firmware verison on all Coldcards or this change can make trouble.
Address type (p2sh-p2wsh, p2sh, p2wsh) is captured from MS wallets created by PSBT file import.
Can now store multiple wallets involving same set of XFP values, if they have differing subkey paths and/or address formats.
New mode which disables certain multisig checks to assist bug compatibility.
Enhancement: Add support for signing Payjoin PSBT files based on BIP-78.
Enhancement: Promoted the address explorer to the main menu. It's useful! (credit to @matt_odell)
Bugfix: zero-length BIP39 passphrase, when saved, would cause a crash when restore attempted. We recommend longer passphrases, but fixed the issue.
Enhancement: Move the "blockchain" setting deeper into the "Danger Zone" and add warning screen. This mitigates a concern raised by @benma (Marko Bencun) where an attacker could socially-engineer you to sign a transaction on Testnet, which corresponds to real UTXO being stolen. Only developers should be using Testnet.
Bugfix: Display of amounts could be incorrect by a few sats in final digits.
Bugfix: Incorrect digest method picked when P2SH-P2WSH incorrectly identified as plain P2SH.
Bugfix: Better error reporting when importing bogus multisig wallet files.
Enhancement: Files created on MicroSD will have date and time determined by the version of firmware that made them. Downstream systems might use this to know when the Coldcard should be upgraded, or which firmware version created the data. Idea from @sancoder
Enhancement: Show version of secure element, under Advanced > Upgrade > Show Version.
Enhancement: Improve 'None of the keys involved...' message to show XFP value actually found inside PSBT file.
Enhancement: "Invalid PSBT" errors are shown with more information now.
Paper Wallet features temporarily removed to free space; will return in future version.
License changed from GPL to MIT+CC on files for which the GPL doesn't apply.

It makes perfect sense since it adds a level of security, if your seed is compromised your funds are gone unless you use a passphrase, the passphrase for the backup is not your seed it is to decrypt the backup which has your seed, if the attacker gets access to your backup passphrase but not to the backup itself you are still safe. Of course you would never have the backup and the passphrase for the backup in the same location.

You understood correctly, but in this case the passphrase to restore the backup it is 12 words, the backup I believe it also includes the pin, duress pin, and brick pin.

Huh ?

What kind of backup is being generated if you still need your 12 word mnemonic ?

Are you sure that you need your mnemonic seed to decrypt the backup file ??
IMO, this wouldn't make much sense. The mnemonic seed should be the backup itself.


As i have understood it, it generates a backup (= encrypted mnemonic seed) which needs a password(?) to be decrypted.

Not for long. They are scared of Passport wallet forking them, so now they are changing the license from open source to creative commons.
Silly people

but are they completely open-source

....googling (duck duck go)

The design of the wallet isn't of primary concern to me. I wouldn't care if it was shaped like a pineapple.
I would be fine with using a USB stick type of device or a simple calculator lookalike.

ColdCard uses a secure element just like Ledger. They are open-sourced, but are they completely open-source, is the code for the secure element also open source or closed source?   

I checked his twitter profile to see if there are any recent tweets in which he was shilling ColdCard in any other capacity. But at least for July there wasn't a single mention. So I guess that recommendation of his is genuine.

Snip

2.0.4 came out on May 13th

From ColdCard:
Release Notes (v2.0.3 – 2.0.4)


-Dave

Firmware v2.1 is out

https://coldcardwallet.com/docs/upgrade



-Dave

2.1.1 came out a few weeks ago.

https://coldcardwallet.com/docs/upgrade

Version 2.1.2 released today.
https://coldcardwallet.com/docs/upgrade

All new firmware since 2.1 have multisig support.

https://coldcardwallet.com/docs/multisig

All changes in 2.1.2


-Dave

Version 2.1.2 released today.
https://coldcardwallet.com/docs/upgrade

All new firmware since 2.1 have multisig support.

https://coldcardwallet.com/docs/multisig

All changes in 2.1.2


-Dave

Version 2.1.3 was released Sep 6, 2019.
This is why I love my ColdCard, they keep working on it, releasing new features and fixes.
Not letting it sit out there like some other wallets.
-Dave

2.1.5 came out the 17-September-2019
There was also a 2.1.4 that was released just after 2.1.3 to fix a small bug

https://coldcardwallet.com/docs/upgrade



This is why everyone should use a coldcard, they keep working on it with regular updates.
It does not just sit there in limbo with no development.

-Dave

New firmware came out yesterday 2.1.6:
https://coldcardwallet.com/docs/upgrade


Just did a test myself with the write receive address to the SD card and it worked.
So that is a cool new feature. Not really sure how many people will use it.

Was thinking creating jpgs with QR codes might be nice. Not sure if it can be done with the hardware.

-Dave

New firmware out as of 1-Nov-2019
Instructions and link to firmware are at https://coldcardwallet.com/docs/upgrade as always.


-Dave

New firmware out as of 1-Nov-2019
Instructions and link to firmware are at https://coldcardwallet.com/docs/upgrade as always.


-Dave

And another new version yesterday:
Login Countdown looks interesting.
As always available here: https://coldcardwallet.com/docs/upgrade


-Dave

Version 3.0.5 out today 25-Nov-2019
As always available here: https://coldcardwallet.com/docs/upgrade

Another great feature PAPER WALLETS that are unrelated to your seed words
Think about that you know you want one.

Going to be playing with that a lot over Thanksgiving.

There is a new firmware out as of the 19th.
https://coldcardwallet.com/docs/upgrade

  Version 3.0.6

Security Bugfix: Fixed a multisig PSBT-tampering issue, that could allow a MitM to steal funds. Please upgrade ASAP.

The usual other changes:


-Dave

There is a new firmware out as of 20-Feb
Something they have at the bottom but should be listed 1st:


A few other updates and additions:



Dropping support for the 1st gen and adding a feature that only works on the 3rd gen is not cool IMO, but I understand that hardware evolves and sometimes has to be replaced.

On the vert very slight chance there is a security issue in the 1st gens that comes out it's going to be interesting to see their reaction.
Will they fix it or will they just say get a new one?

-Dave

Another update as of today 27-Feb-2020:

Version 3.1.2 - Feb 27, 2020


Since the Mk1 are no longer supported if you contact them at [email protected] with your original Coinkite order ID they are offering 25% off a new one.
I feel it should be more but that's just me.

-Dave

The I am talking to myself in this thread post about new firmware.
Version 3.1.3 is now out.

https://coldcardwallet.com/docs/upgrade   <-- Remember don't just trust my links verify for yourself.


Looks like some minor stuff, but they keep developing and updating unlike some other hardware wallet people.

And remember V1 hardware is no longer supported

Stay safe.

-Dave

Version 3.1.5 - June 13, 2020
Enhancement: Detect, report and block the recently reported type of attack against BIP-143 (replay of segwit inputs) with an error message. No changes needed to your input PBST files. Will show errors similar to: "Input#0: Expected 15 but PSBT claims 5.00001 BTC"
Enhancement: When the Coldcard is finalizing the transaction, we show the TXID (hex transaction ID) of the transaction on the screen.
Enhancement: Export deterministically-derived entropy in the form of seed phrases (BIP39), XPRV, private key (WIF), or hex digits using new BIP-85 standard. Useful for seeding other wallets from your Coldcard, so you don't need to backup "yet another" seed phrase. Derived values (all types) can be easly recreated from Coldcard later, or the backup of the Coldcard. Does not expose the Coldcard's master secret, should new wallet be compromised.
Bugfix: When scrambled keypad used with the login delay feature, the PIN-entry sequence was not scrambled after the forced delay was complete. Thanks to an anon customer for reporting this.
Bugfix: Scrambled keypad didn't change between PIN prefix and suffix.
Enhancement: QR Code rendering improved. Should be more readable in more cases. Faster.
Enhancement: View percent consumed of the settings flash space (just for debug)
Enhancement: New command to clear the UTXO history, in rare case of false positive.
(v3.1.5) Bugfix: Signing PSBT with finalization from MicroSD card, did not work. Error about "HexWriter" was shown.

HSM (Hardware Security Module) mode: give Coldcard spending rules, including whitelisted addresses, velocity limits, subsets of authorizing users ... and Coldcard can sign with no human present. Requires companion software to setup (ckbunker or ckcc-protocol), and disabled by default, with multi-step on-screen confirmation required to enable. Mk3 only.

Enhancement: New "user management" menu. Advanced > User Management shows a menu with usernames, some details and a 'delete user' command. USB commands must be used to create user accounts and they are only used to authenticate txn approvals in HSM mode.

I don't quite get what perceived threat this is attempting to mitigate? Surely it doesn't actually increase security in anyway? I mean, if someone has your PIN, they have your PIN... making them wait an extra few minutes doesn't change that fact... Is it meant to allow you time to restore your wallet/move the funds in the case that the device is stolen? Surely, a (decent) BIP39 passphrase achieves the same thing?

I can only imagine that it would piss me off having to wait X seconds or X minutes every time I wanted to use the device... and I certainly can't imagine any scenario in which such a delay would need to be measured in "days"!!?!

Login Countdown looks interesting.

ColdKite recently share their Coldcard Hardware Details at https://blog.coinkite.com/coldcard-hardware-shared/ and apparently you can build your own Coldcard.

Honestly, It's not worth it, at least not for 69.99$. The design alone is not attractive, let alone the features.

the ColdCard looked cheap in the photos but holding in my hand it's worth the price.

I keep mine sealed in a gasketed plastic case. I got it out the other day, and some numerals were not typing. I will play around with it more before I panic, but I have seed words saved.

Touch pad is not doing what I want (Mark1 only)
Phantom keypresses have been a problem for some users. Here are some debug steps:

Install version 1.0.1 or later of the firmware.
Change the touch setting to suit your preferences and needs.
Press X twice before entering PIN; that selects the least sensitive mode.
Use a quality USB power supply. Often a battery pack is best for this.
Move to a different environment. Moisture in the air can be an issue.
One customer reported this:

I did some testing and it seemed that any computer plugged to the grid is plagued by noise, after connecting the wallet to an offline laptop running on battery power, I had zero issues with the touchpad.

I just got mine today - I am really enjoying using ColdCard + Electrum, and displaying my addresses on the display. Managing multiple wallets is easy, and i can unplug and keep unencrypted wallets watch-only to see the confirms roll in.    

I still like the Trezor, but ColdCard is a straightforward BTC/LTC only-wallet that can be used tethered, or setup as airgapped.   I tried it on wasabi, but i prefer how i can keep multiple wallets open in electrum.  

the ColdCard looked cheap in the photos but holding in my hand it's worth the price.  it's obvious someone put a lot of thought and pride into how these turned out. Great buttons on the v2. The serial number on the sealed bag matched the bag number located in the firmware for security during shipment too.  

imo if someone is btc-only and likes tactile buttons over touchscreens, i'd go with a ColdCard.  

i was looking for a new desktop wallet and found out about this integration with coldcard.  i'm also impressed with the thoughtful design of the hardware down to the tamper-evident, clear case.   I have ordered a hardware v.2 to try out.

Export skeleton wallets for Wasabi Wallet https://wasabiwallet.io/ to support air-gapped use.

Not a bad deal there, really. I'm good on hardware wallets, I depend on cold wallets for real storage. What card storage would be more convenient for you? Many phones use that card, so it's handy in that aspect. Larger cards require/waste more circuit board real estate, and larger form factor.

I don't have a Trezor, but have a couple of Ledger Nano S wallets. One seemingly unique feature is the MicroSD slot. From their docs:

Why does it have a MicroSD slot?

    The Coldcard can backup the seed into an encrypted file.
    New transactions to be signed, can be imported from the card.
    Public key data (xpub, receive addresses) can be written onto the card.
    Firmware upgrades can be done by copying the new firmware file onto a card.
    A skeleton Electrum wallet can be created on the card which allows Electrum to "pair" with the Coldcard, without it ever connecting to a USB port.

The second one, in particular is interesting, as it makes completely air-gapped transactions possible. I don't know of any others that can do that, at any price. There may be, I just don't know about them.

Here's a recent review of the Coldcard.

EDIT a few minutes later
Got it working with Electrum 3.23  had to add 51-coinkite.rules to /etc/udev/rules.d   Reloaded udev stuff with sudo udevadm control --reload-rules && sudo udevadm trigger

info here: https://github.com/Coldcard/ckcc-protocol/blob/master/51-coinkite.rules

Huh ?

What kind of backup is being generated if you still need your 12 word mnemonic ?

Are you sure that you need your mnemonic seed to decrypt the backup file ??
IMO, this wouldn't make much sense. The mnemonic seed should be the backup itself.


As i have understood it, it generates a backup (= encrypted mnemonic seed) which needs a password(?) to be decrypted.

{snip} I have not tried p2sh-segwit. The latest Sept 11 firmware says:

Can create Electrum skeleton wallet for Segwit Native and Segwit P2SH now.
    caveat: the plugin is not ready yet for P2SH/Segwit, but Segwit native is fine

https://coldcardwallet.com/docs/upgrade  

I do like that Electrum 3.23 lets you upgrade the Coldcard firmware directly via USB, without an SD card.

Have you been able to sign transaction for p2sh-segwit format? I have only been able to sign for legacy format. The electrum wallet file for p2sh-segwit does not recognise my coldcard, whereas the wallet file using p2pkh format does recognise it.

I have tried the backup option. It creates a 12 word mnemonic that acts as the pass phrase to decrypt it.

It is certainly an interesting concept. It can be used as an "offline signer" in conjunction with Electrum... so instead of using a 2nd computer, you simply transfer the unsigned transaction to your coldcard via a microSD, sign it, then transfer it back to your online PC and broadcast.

However, my concern lies with the fact that the microSD can also be used to "update firmware"... and "backup your (encrypted) seed".

I wonder how long before someone figures out a way to update the firmware so that it creates an unencrypted backup of your seed on the microSD card

I have one, and sort of like it so far. I got in on the startup thing, so I got it I think $10 cheaper. I have not put any BTC on it yet, still learning. I have a Ledger Nano S, but it seems that Coldcard has the ability to do a few unique things (most notably, sign transactions completely off-line).

I am still in 'dabbling-mode' with the Ledger Nano S as well, so I am in no position to make an informed comparison. I've been in the space a while, the lack of alt-coins does not bother me, I'm only interested in BTC.

I see that the latest Electrum supports it directly, so a familiar software wallet (for me) that works with it will be great. I need to tweak udev in Linux apparently, haven't got it completely working yet.

I HODL, so all of this is just experimentation so far.

EDIT a few minutes later
Got it working with Electrum 3.23  had to add 51-coinkite.rules to /etc/udev/rules.d   Reloaded udev stuff with sudo udevadm control --reload-rules && sudo udevadm trigger

info here: https://github.com/Coldcard/ckcc-protocol/blob/master/51-coinkite.rules

It is certainly an interesting concept. It can be used as an "offline signer" in conjunction with Electrum... so instead of using a 2nd computer, you simply transfer the unsigned transaction to your coldcard via a microSD, sign it, then transfer it back to your online PC and broadcast.

However, my concern lies with the fact that the microSD can also be used to "update firmware"... and "backup your (encrypted) seed".

I wonder how long before someone figures out a way to update the firmware so that it creates an unencrypted backup of your seed on the microSD card

Honestly, It's not worth it, at least not for 69.99$. The design alone is not attractive, let alone the features.

You could add more money and get a Trezor for 69 EUR (excl. VAT) and enjoy more features, frequent updates, big userbase, faster support etc.