[ESHOP launched] Trezor: Bitcoin hardware wallet

[JorgeStolfi]

Your bitcoin keys will be safer if stored in a Trezor than in your PC or smartphone, for sure.  However the risk will still be significant.

Even with Trezor, stealing your bitcoins may still be easier than stealing money from your bank account or credit card, and it will certainly be much safer for the thief.  Thus we can be sure that legions of black-hat hackers and criminals will turn their attention to methods of stealing bitcoins from Trezor users.

Even if your Trezor works as it is supposed to, you will still be vulnerable to attacks like address phishing (the hacker tricks you into sending payment to the wrong address) and man-in-the-middle (a compromised PC software displays the correct destination address on the screen, but puts the thief's address in the transaction that it gives Trezor to sign.  While an alert user can notice the substitution by checking the Trezor's display, there will inevitably be users who check only the PC screen, out of laziness or because they are not aware of the risk.)

If you use your Trezor anywhere outside your home,  whatever you do to unlock it (passwords, PIN, voiceprints, secret handshakes...) can be recorded and used by someone who later steals the device.  Even in your home, a burglar, janitor, or trusted visitor may plant a camera or other recording equipment, without you noticing.  (Paranoid physical security measures may actually increase that risk: google the death of banker Edmund Safra for an example.)

Then there is the possibility that the device does not work as intended.  It may have a bug (like the classical buffer overrun) that is discovered by a hacker and can be exploited by a malicious software in the PC to extract the private keys.  Perhaps the designers left a secret backdoor, in case some Russian mobster or the CIA pays them a visit with a Trezor whose keys they really want to get.  If Trezor uses custom chips, perhaps someone switched the tapes on the way to the foundry, or substituted the chips on the way back.  Perhaps someone replaced your Trezor by a compromised one, in transport or anytime after you got it.  (Ask any magician how it can be done under your nose.)  

Even one successful bitcoin theft could net millions of dollars.  Therefore, we cannot ignore some possible theft method (like substituting chips at the factory, or posing as the cable repairman) just because it would require thousands of dollars of investment, or several months of work.

Indeed, the Trezor gadget may have been invented and sold specifically for the purpose of stealing your coins.  (This is only a thoretical risk, of course: from their website we can see that the creators are two young honest-looking bitcoin entrepreneurs, and I could not find in CoinDesk or other bitcoin avocacy sites any mention of young honest-looking bitcoin entrepreneus who turned out to be thieves or scammers.)

if your Trezor device is malicious, buggy, modified, or fake, obviously all bets are off, and there is no point in enumerating all the ways it could steal your bitcoins.

It seems very difficult to check whether your device is legitimate and unmodified, and that the software that it is running is the same that is posted on github. This is the same basic shortcoming of all-electronic voting machines, like the Brazilian one.  The latter has many "security" features, like verifiable cryptographic checksums of the executable code, "tamper-proof" seals, and redundant output reports; and, moreover, at every election some units are picked at random for a public test in parallel with the real voting.  Yet, as experts will tell you, all these measures are worthless because they can be easily bypassed by hackers who can target them from inside the organization.

[AussieHash]

Ok. Well how about Cold offline storage for most coins and Trezor for the hot wallet, and a few dollars on the smartphone ?

[mmeijeri]

Even if your Trezor works as it is supposed to, you will still be vulnerable to attacks like address phishing (the hacker tricks you into sending payment to the wrong address) and man-in-the-middle (a compromised PC software displays the correct destination address on the screen, but puts the thief's address in the transaction that it gives Trezor to sign.  While an alert user can notice the substitution by checking the Trezor's display, there will inevitably be users who check only the PC screen, out of laziness or because they are not aware of the risk.)

I'm not sure if Trezor supports it already, but shouldn't the payment protocol solve that particular problem?

[stick]

I'm not sure if Trezor supports it already, but shouldn't the payment protocol solve that particular problem?

Yes, it does solve it. Payment protocol is planned for the future TREZOR releases.

[cor]

Ok. Well how about Cold offline storage for most coins and Trezor for the hot wallet, and a few dollars on the smartphone ?

You don't need a cold offline storage when you have a Trezor. Trezor is an "offline storage" with a transaction signing functionality on top.

When you want to use coins from a cold storage, you have to load your private keys into a wallet. That might be a short moment but enough for a malware to catch it.

Also, a cold storage might require advanced computer skills and understanding of bitcoin. Trezor on the contrary can be easily used by my mom.

[cor]

Even if your Trezor works as it is supposed to, you will still be vulnerable to attacks like address phishing (the hacker tricks you into sending payment to the wrong address) and man-in-the-middle (a compromised PC software displays the correct destination address on the screen, but puts the thief's address in the transaction that it gives Trezor to sign.  While an alert user can notice the substitution by checking the Trezor's display, there will inevitably be users who check only the PC screen, out of laziness or because they are not aware of the risk.)

That's true. It is one of our main goals to educate our users on the few risks left after they purchase a Trezor:

• store your recovery seed in a safe place, prevent it's misusage
• don't forget your encryption passphrase if you are using this advanced option
• use a different channel to verify the payment address received through internet (phone, in person...)

Visual (dsiplay) and physical verification (button press) is one of the key security properties of Trezor. If someone is not using it for his advantage, he doesn't understand the threats. Again, education is important.

If you use your Trezor anywhere outside your home,  whatever you do to unlock it (passwords, PIN, voiceprints, secret handshakes...) can be recorded and used by someone who later steals the device.

PIN - can't be logged, please search for the Trezor PIN matrix.
passphrase - best practice  when you need to use a public computer, just have a small spending amount without a passphrase

 It may have a bug (like the classical buffer overrun)...
that is discovered by a hacker and can be exploited by a malicious software in the PC to extract the private keys.

security researchers that tested Trezor were a bit disappointed that they couldnt trick Trezor with  buffer overflow
 

Perhaps the designers left a secret backdoor

it's opensource, everybody can check and believe me they are doing that..

If Trezor uses custom chips, perhaps someone switched the tapes on the way to the foundry, or substituted the chips on the way back.  

Our manufacturer is sourcing standard material with their long-time partners audited on a regular basis AND without them ever knowing the final product.

Perhaps someone replaced your Trezor by a compromised one, in transport or anytime after you got it.  (Ask any magician how it can be done under your nose.)  

That might be risky BUT if you are not completely naive, you 1. check the integrity of the package before you use the device, 2. only buy it from official/trusted shops 3. the casing cannot be opened without damaging it so replacing internals won't be easy
if you do the above and still not sure, contact our support, we might have some ways to determine further (no, no privacy breach will be done)

It seems very difficult to check whether your device is legitimate and unmodified, and that the software that it is running is the same that is posted on github.

http://satoshilabs.com/news/2014-06-22-wanted-independent-trezor-code-reviewers/

[Anon136]

Perhaps someone replaced your Trezor by a compromised one, in transport or anytime after you got it.

Of all the risks mentioned, this is the most realistic one I think. The nsa has actually been caught doing this to routers. http://www.engadget.com/2014/05/16/nsa-bugged-cisco-routers/ Too bad you cant create and compare a hash of hardware configurations. Do you think your aforementioned security precautions would thwart such a sophisticated attacker as this?

[JorgeStolfi]

If you use your Trezor anywhere outside your home,  whatever you do to unlock it (passwords, PIN, voiceprints, secret handshakes...) can be recorded and used by someone who later steals the device.

PIN - can't be logged, please search for the Trezor PIN matrix.

By "recording" I do not mean just keylogging, but (e.g.) placing a hidden hi-res camera in the right spot.

passphrase - best practice  when you need to use a public computer, just have a small spending amount without a passphrase

One may have to use a public computer for realtively large sums, e.g. pay a hotel bill or run a business remotely while on vacation in a remote place.

security researchers that tested Trezor were a bit disappointed that they couldnt trick Trezor with  buffer overflow

I did not mean bufer overflow explicitly (no programmer should make that mistake any more) but some other subtle bug that can be exploited to breach the security.

"It is easy to write correct software, you just have to remove all its bugs. And it is easy to remove all bugs, you just have to remove the last one." 
 

Perhaps the designers left a secret backdoor

it's opensource, everybody can check and believe me they are doing that..

But there is no easy way to make sure that the software that they are checking is what is stored in the device, is there?

1. check the integrity of the package before you use the device

A criminal who sets out to physically hack a rich man's Trezor during delivery will surely be able to provide a neatly sealed package that will fool him.

2. only buy it from official/trusted shops 3. the casing cannot be opened without damaging it so replacing internals won't be easy

Most devices will be bought via internet and delivered by UPS or the like.  International purchases will be particularly risky since the packages may sit to weeks at customs and be opened by them.

The Trezor's exterior is quite simple, so it seems relatively easy to make a fake one that looks and feels like the original.  The copy can be swapped for the original, without the owner noticing, and can be designed to steal the PIN and/or passphrase and transmit it to the thief, e.g. by bluetooth. (This attack would be similar to the "chupa-cabra" that thieves attach to ATMs to steal card data and PINs).

[stick]

But there is no easy way to make sure that the software that they are checking is what is stored in the device, is there?

We prepared a deterministic build environment, so it's easy to compile the firmware from source and produce bit identical binary to ours and compare them (or their hashes).  We'll prepare more materials about how to check this/participate in the signing on the next firmware update.

[klokan]

Your bitcoin keys will be safer if stored in a Trezor than in your PC or smartphone, for sure.  However the risk will still be significant.

Even with Trezor, stealing your bitcoins may still be easier than stealing money from your bank account or credit card, and it will certainly be much safer for the thief.  Thus we can be sure that legions of black-hat hackers and criminals will turn their attention to methods of stealing bitcoins from Trezor users.

If there are hidden cameras everywhere, all hardware is NSA hacked and user is not looking at the screen before sending all his money to thief, then the user probably cannot do safe transaction with credit card either.

Don't get me wrong. I think that it is important to talk about these risks and educate users. But if there is nothing what can be done, then engaging in such discussion is useless.

So what can be done that would in your opinion make this safer than your credit card? If I have hacked computer, then thief can steal my money from my bank account. If I have cameras in my appartment, then he might steal from me as well. I have received my computer, credit cards and bank details by post and if NSA or goverment wanted they can block and empty my bank account whenever they wanted.

The added security of this device is that it has to be either bugged or fake or malitious to steal from you and even if it is, then it still needs your computer cooperation, i.e., your computer being hacked, to do it. It is much higher security compared to just storing your keys on your computer. Especially for lumberjack Jack, who never saw linux before.

[JorgeStolfi]

If there are hidden cameras everywhere, all hardware is NSA hacked and user is not looking at the screen before sending all his money to thief, then the user probably cannot do safe transaction with credit card either. [ ... ] So what can be done that would in your opinion make this safer than your credit card? If I have hacked computer, then thief can steal my money from my bank account. If I have cameras in my appartment, then he might steal from me as well. I have received my computer, credit cards and bank details by post and if NSA or goverment wanted they can block and empty my bank account whenever they wanted.

As I wrote, using a Trezor is surely safer than entering or storing keys in your PC or laptop, and you may even dare to use it on a random cybercafe computer (which you should never entrust with your keys).

However, users must be aware that the risk of theft is still not negligible, and they must still be very careful when using the Trezor -- even more than when using credit cards or home banking.

Consider the entire process of stealing money from your account or credit card, including what the thief needs to do to get the cash in hand once he has stolen the PIN or passwords, and what you can do once you discover the theft.  Bitcoin makes the theft much simpler and safer for the thief, and he can effectively collect bicoins stolen from thousands of wallets on the same day, without even being logged in at the time.  Bitcoin thefts have proven to be nearly impossible to solve; the stolen coins cannot be blocked or seized, and are easily laundered with little risk.

For those reasons, and more, bitcoin is extremely attractive to professional cybercriminals.  It is no wonder that there are already more bitcoin thefts than credit card thefts, in proportion to the total e-payments.  

I think that it is important to talk about these risks and educate users. But if there is nothing what can be done, then engaging in such discussion is useless.

Of course it is very important to discuss these issues.  I don't know the details of the hardware & software, but I am sure that its safety can be improved in many ways.

For example, it is still not clear to me whether there is any practical way to check that the firmware that is loaded in a particular Trezor device is the official one.  (This is the fundamental fatal flaw of every all-digital voting machine design, and there is still no known solution for it.)

[stereotype]

Thought someone had sent me some 'safe payment system' condoms! 

Thanks Trezor

[klokan]

If there are hidden cameras everywhere, all hardware is NSA hacked and user is not looking at the screen before sending all his money to thief, then the user probably cannot do safe transaction with credit card either. [ ... ] So what can be done that would in your opinion make this safer than your credit card? If I have hacked computer, then thief can steal my money from my bank account. If I have cameras in my appartment, then he might steal from me as well. I have received my computer, credit cards and bank details by post and if NSA or goverment wanted they can block and empty my bank account whenever they wanted.

As I wrote, using a Trezor is surely safer than entering or storing keys in your PC or laptop, and you may even dare to use it on a random cybercafe computer (which you should never entrust with your keys).

However, users must be aware that the risk of theft is still not negligible, and they must still be very careful when using the Trezor -- even more than when using credit cards or home banking.

Consider the entire process of stealing money from your account or credit card, including what the thief needs to do to get the cash in hand once he has stolen the PIN or passwords, and what you can do once you discover the theft.  Bitcoin makes the theft much simpler and safer for the thief, and he can effectively collect bicoins stolen from thousands of wallets on the same day, without even being logged in at the time.  Bitcoin thefts have proven to be nearly impossible to solve; the stolen coins cannot be blocked or seized, and are easily laundered with little risk.

For those reasons, and more, bitcoin is extremely attractive to professional cybercriminals.  It is no wonder that there are already more bitcoin thefts than credit card thefts, in proportion to the total e-payments.  

I think that it is important to talk about these risks and educate users. But if there is nothing what can be done, then engaging in such discussion is useless.

Of course it is very important to discuss these issues.  I don't know the details of the hardware & software, but I am sure that its safety can be improved in many ways.

For example, it is still not clear to me whether there is any practical way to check that the firmware that is loaded in a particular Trezor device is the official one.  (This is the fundamental fatal flaw of every all-digital voting machine design, and there is still no known solution for it.)

The problems you describe (like the anonymity, etc.) are the features of BTC and these are thus inherent to all BTC wallets. Once you are robbed, you can do nothing about it. I agree with you. That is not a bug, that is the feature. I know that this makes BTC attractive to the criminals, but I disagree that this makes this device less secure.

I'm not sure whether you can verify the firmware running on the device, but you can always flash it with the latest firmware from the website or your own build. That said, there is still bootloader that might be hacked, but that would have to happen in production because it cannot be overwritten. That would be equivalent to having a fake one.

[JorgeStolfi]

I'm not sure whether you can verify the firmware running on the device, but you can always flash it with the latest firmware from the website or your own build. That said, there is still bootloader that might be hacked, but that would have to happen in production because it cannot be overwritten. That would be equivalent to having a fake one.

Wait, I am confused.  Do you mean that the firmware can be replaced after the device was assembled?  If so, what is the procedure to do that?

[dnaleor]

I'm not at home, but got a call from my dad. The trezor package arrived! 

[klokan]

I'm not sure whether you can verify the firmware running on the device, but you can always flash it with the latest firmware from the website or your own build. That said, there is still bootloader that might be hacked, but that would have to happen in production because it cannot be overwritten. That would be equivalent to having a fake one.

Wait, I am confused.  Do you mean that the firmware can be replaced after the device was assembled?  If so, what is the procedure to do that?

Yes, it can be replaced. The official firmware releases are available from the trezor website and are signed by satoshilabs. you can load unsigned firmware and in this case bootloader will warn you ask you for confirmation that this is really what you want.

[Mitchell]

I'm not at home, but got a call from my dad. The trezor package arrived! 

Awesome! I wish I had ordered one during the 0.5BTC promotion. Oh well, I hope you enjoy yours! Makes some pictures and show them to us!

[Coiner.de]

Do you mean that the firmware can be replaced after the device was assembled?  If so, what is the procedure to do that?

The official procedure is rather nicely shown here: http://doc.satoshilabs.com/trezor-user/updatingfirmware.html

[JorgeStolfi]

Do you mean that the firmware can be replaced after the device was assembled?  If so, what is the procedure to do that?

The official procedure is rather nicely shown here: http://doc.satoshilabs.com/trezor-user/updatingfirmware.html

Hm... What if someone get holds of your Trezor without your knowledge, installs malicious firmware that saves your passphrase, returns it to you, then steals it again after you have used it, and downloads the pasphrase?  Or whaterver?

[klokan]

Do you mean that the firmware can be replaced after the device was assembled?  If so, what is the procedure to do that?

The official procedure is rather nicely shown here: http://doc.satoshilabs.com/trezor-user/updatingfirmware.html

Hm... What if someone get holds of your Trezor without your knowledge, installs malicious firmware that saves your passphrase, returns it to you, then steals it again after you have used it, and downloads the pasphrase?  Or whaterver?

You have to confirm that you want to run it with unsigned firmware every time you plug it in.