TANGEM WALLET: An Innovative Seedles Cold Wallet Setup

[satscraper]

Bypassing Tangem Card Security with a Laser Attack

I guess dkbit98 was right after all when he repeatedly warned everyone to stay away from tangem crap  
They have terribly bad products on both hardware and software level, and there is no way they can fix that.
Good job from Donjon research team yet again, they are the only bright spot in ledger team.

PS
Donjon should try to do the same thing with Satochip cards, if they can  

Don't see why it would be any more difficult to do Satochip or any other card. If you have the time and money and are willing to put in the effort it's been proven that it can be done.
Fly to Vegas for Black Hat / DefCon next month. And see what unhackable things are hacked live onstage.

Exactly, dkbit98 just cannot get that laser fault injection as used by Donjon is the plausible threat for any SE, Satochip included. Satochip may be even crappier, because the weak points in its logic can be easily revealed from the open-source Java applet it runs, so, unlike with Tangem, precisely timed fault injection via laser beam to break its security could be done with minimal effort.

Let's forgive dkbit98 for their remark.

[fillippone]

Again, just remember what those devices are meant to be used for.
If you load more than your pocket money on one of those cards, it's your fault.
Of course, there are methods to extract money from your Tngem, but of course, there are better-suited products to store higher amounts of satoshi.
I guess how easy it is to extract the money from your physical wallet.

[Meuserna]

Again, just remember what those devices are meant to be used for.
If you load more than your pocket money on one of those cards, it's your fault.
Of course, there are methods to extract money from your Tngem, but of course, there are better-suited products to store higher amounts of satoshi.
I guess how easy it is to extract the money from your physical wallet.

Absolutely. I cringe when I see people talking about using Tangem to secure their hodl. But it's fine for what I refer to as a walk-around-wallet. A little Bitcoin on the go? Something like this is fine. For long term holding? Yikes. No.

For long term holding, I think seedless wallets are a disaster waiting to happen. A seed phrase is such a brilliant form of physical backup. If something goes wrong, all you need to get your Bitcoin back is your seed phrase. Buy a new hardware wallet. Almost any kind. Or use a hot wallet if it's truly an emergency.

A seed phrase in metal is such a brilliant form of backup.

[satscraper]

Again, just remember what those devices are meant to be used for.
If you load more than your pocket money on one of those cards, it's your fault.
Of course, there are methods to extract money from your Tngem, but of course, there are better-suited products to store higher amounts of satoshi.
I guess how easy it is to extract the money from your physical wallet.

Absolutely. I cringe when I see people talking about using Tangem to secure their hodl. But it's fine for what I refer to as a walk-around-wallet. A little Bitcoin on the go? Something like this is fine. For long term holding? Yikes. No.

For long term holding, I think seedless wallets are a disaster waiting to happen. A seed phrase is such a brilliant form of physical backup. If something goes wrong, all you need to get your Bitcoin back is your seed phrase. Buy a new hardware wallet. Almost any kind. Or use a hot wallet if it's truly an emergency.

A seed phrase in metal is such a brilliant form of backup.

For long term holding any single wallet may turn into a disaster. A multisig setup seems to be more appropriate for this.

BTW, Tangem may work as a BIP-39-compliant wallet. It is the user's choice what mode to use seedless or SEED based. I use the seed child derived from a master seed generated by Passport Core.

[Meuserna]

For long term holding any single wallet may turn into a disaster. A multisig setup seems to be more appropriate for this.

I don't agree.

A 12 word seed phrase is incredibly secure so long as it was generated by a trustworthy device. A 24 word seed phrase is even more secure (perhaps even overkill).

BTW, Tangem may work as a BIP-39-compliant wallet. It is the user's choice what mode to use seedless or SEED based. I use the seed child derived from a master seed generated by Passport Core.

To be used that way, doesn't Tangem require the user to enter the seed phrase on a phone? That violates self custody best practices: Never type your seed phrase on a computer, tablet or phone (or any device directly connected to the internet).

To be honest, I'm not a Tangem fan. I'd never recommend any wallet that doesn't follow best practices.

[satscraper]

For long term holding any single wallet may turn into a disaster. A multisig setup seems to be more appropriate for this.

I don't agree.

A 12 word seed phrase is incredibly secure so long as it was generated by a trustworthy device. A 24 word seed phrase is even more secure (perhaps even overkill).

You have to agree as this has little to do with seed phrase security. Opposite to the single wallet multisig setup protects your funds in the event that one of your cosigners is compromised  whether through a side channel attack,  supply chain attack, or any other vector.

Never type your seed phrase on a computer, tablet or phone (or any device directly connected to the internet).

Definitely.  Initializing Tangem card with SEED phrase works fully offline, since it happens over NFC between phone and card, not through Internet or cellular networks.

I'd never recommend any wallet that doesn't follow best practices.

Glad for you.

Also it would be good practice for you not to put  your two cents in on wallets when you lack relevant knowledge and hands-on experience.


Meanwhile Tangem app has been elevated to v.6.0 featuring the cleaner feel to main screen, token screen, markets, and Tangem Pay as well as better swaps ^{meaning  BTC can now swap via DEX (LiFi, SwapKit)}, and Tangem Pay flexibility. Also it applied some small fixes as always.

[Meuserna]

Initializing Tangem card with SEED phrase works fully offline, since it happens over NFC between phone and card, not through Internet or cellular networks.

The concern isn't whether the seed reaches the card over NFC or Wi-Fi. The concern is that the seed is generated or entered on a phone in the first place.

It happens on a phone.

That is generally not considered a best practice for securing significant amounts of Bitcoin. And to use your own seed phrase on a Tangem, you have to enter the seed phrase on a phone, which should not be done.

I recognize that Tangem is, among other things, trying to solve a problem: the need for convenient cold storage that is more easily portable. But I think seedless wallets are risky for anything more than small amounts of Bitcoin because they provide no form of human readable backup.

Human readable backups (seed phrases) help keep people's Bitcoin safe in a worst case scenario.

Seed phrases should not be entered on a phone, even if they'll be transmitted over NFC not wifi.

I'd never recommend any wallet that doesn't follow best practices.

Glad for you.

Also it would be good practice for you not to put  your two cents in on wallets when you lack relevant knowledge and hands-on experience.

This isn't the first time you've attacked me. If you have a personal issue with me, I don't know what it is, nor am I even interested. We're here to discuss hardware wallets.

If you see no issue with generating seed phrases on a phone, that's your opinion. But please don't recommend others ignore best practices. That's potentially dangerous.

[fillippone]

Technically, the Tangem wallets are cold wallets, meaning the seed phrase is never exposed online.
Reality is, those cold wallets are not secure for storing a large sum of bitcoins or for a long time.
Again, each one of us has to assess their personal threat model, deciding if this solution is correct for their unique needs.

[satscraper]

Technically, the Tangem wallets are cold wallets, meaning the seed phrase is never exposed online.

Yeah, this is correct. You may disable all long-range electromagnetic communications on your mobile device and initialize your Tangem cards.

There is an even more rigorous approach for especially paranoid people. They may initialize their cards on the cheap offline mobile device, then take a hammer and destroy that device, and then use already initialized cards on the  fresh mobile with  Tangem app installed.

Reality is, those cold wallets are not secure for storing a large sum of bitcoins or for a long time.

The reality is that no single wallet is secure for long time.

As I already said in my post above, the multisig setup provides more security for your stash.

But the full truth is that any type of wallet ^{multisig, MPC, etc}. is insecure for long term storage, because those hunting for Bitcoin don't care about your wallets. All they need to know is that you have crypto and your address. Nothing else. Then  $5 wrench will do the rest. So for long term storage your personal OPSEC comes into play.

[DaveF]

There is an even more rigorous approach for especially paranoid people. They may initialize their cards on the cheap offline mobile device, then take a hammer and destroy that device, and then use already initialized cards on the  fresh mobile with  Tangem app installed.

https://www.youtube.com/shorts/fVhC74k509w


As I think a lot of us keep saying, everyone has to do their own paranoia level for security.

I consider Tangems OK security because of their nature and how I use them NOT because they are only OK.
I have a hot multicoin wallet on my phone. I don't think it's secure but I don't care it's not "real" money.
Tangem is also installed and used, but due to their nature I have the card with me so I can make slightly larger (but still not "real" amounts) transactions.

But how secure is it, as I said above pull a gun / knife on me here is the phone here is my wallet.

Real cold large amount storage is a totally paranoid setup.

But, I think a lot of people who use Tangem and similar cards are like me. Card in wallet carried with you along with your phone.

-Dave

[satscraper]

Now, while the ColdCard drama is still unfolding, Tangem owners might want to dig deeper into the subject of entropy relevant to their wallets. They could find the relevant details here and read for themselves, but I took the liberty of making a short and descriptive summary which highlights the gist.

In seedless mode, Tangem relies on the card's secure chip, which has a built-in hardware RNG. It captures physical noise ^{like heat, electronic jitter, whatever} inside the chip, cleans up that noise into truly random bits, and uses 256 of those bits directly as the private key. The key is checked to make sure it meets the requirements for secp256k1.

In seed phrase mode, the randomness is generated by your phone instead of the card. It uses the phone's built-in secure random number generator (iOS or Android's system-level RNG, fed by the OS's entropy pool).

I initialized my Tangem cards with a child SID generated by Passport Core according to the BIP-85 protocol from its extended master SEED. I did this because the avalanche diode used by Passport Core for entropy is one of the best sources of it.

[satscraper]

Tangem app was elevated to v.6.1 ^{for both Android and IOS}. This release gives verified users their own real US bank account and routing number, so they can get paid directly, with funds landing as USDC on Polygon. There's also a new Address Book feature, so users can save wallet addresses with nicknames and send with one tap instead of copy-pasting long addresses. Finally, Tangem Pay now has membership tiers (Basic, Plus, and a coming-soon Prestige) tied to Visa benefit levels.

[satscraper]

I have a hot multicoin wallet on my phone. I don't think it's secure but I don't care it's not "real" money.
Tangem is also installed and used, but due to their nature I have the card with me so I can make slightly larger (but still not "real" amounts) transactions.

Your setup seems sound, but I wonder if there's any point ^{besides transaction speed} to keeping both the  multicoin wallet ^{(which one?)} and Tangem app on  phone simultaneously. Tangem app covers almost all available blockchains and is far more secure than any other mobile wallet because it keeps private keys outside the phone.

[DaveF]

I have a hot multicoin wallet on my phone. I don't think it's secure but I don't care it's not "real" money.
Tangem is also installed and used, but due to their nature I have the card with me so I can make slightly larger (but still not "real" amounts) transactions.

Your setup seems sound, but I wonder if there's any point ^{besides transaction speed} to keeping both the  multicoin wallet ^{(which one?)} and Tangem app on  phone simultaneously. Tangem app covers almost all available blockchains and is far more secure than any other mobile wallet because it keeps private keys outside the phone.

A bit of tin foil hat paranoia and speed.
I use coinomi for the quick transactions, yeah I know, but it's a lot of inertia on my part, and it works for what I need it for. It has some DOGE, LTC, ETH (under $20 of each) and bit of BTC (under $50). I can have the phone our and a QR code scanned in no time at all.

For larger amounts I use Tangem. BUT, it's password, biometric and card. Still under a few hundred dollars of BTC on it. With having to stop, and do all that and dig out my wallet for the card it's not worth it for the $6 coffee purchase thing. Not to mention I am the king of "did I leave my wallet at the office?" Or "did I leave my wallet at home". So there is that too.

Bit of the way the world has changed, but 25 years ago I would never leave without being 100% certain that I had my wallet with me. Phone 95% of the time but it was not totally critical. Now, with tap to pay, crypto and everything else on the phone, it's just less important to have your wallet with you. But never leave without the phone.

-Dave