5 ms·

The TREZOR people have posted on Reddit that this article is describing a known issue which was fixed in the last firmware update yesterday.

londons_explore 9y ago
If the secret key is stored in a reversible way in a chip not designed against physical attacks, I fail to see how they could do a software fix? Sure they might have stopped anything getting copied to SRAM, but the data is still sitting there in flash ready to be read out by almost any method.
- celticninja 9y ago
  Article claims it works against unreleased Trezor V2 and software version 1.5.2 but Trezor say this is incorrect. So I would take the claims with a pinch of salt, especially they are charging almost $9k to download the software
- sowbug 9y ago
  Any secret must be stored "in a reversible way" or else it's useless.
  - jjnoakes 9y ago
    Right, but then you should store it "in a chip designed against physical attacks", as the person you replied to mentioned.
    - sowbug 9y ago
      That isn't a panacea. Even though secure elements today have clever defenses against physical attack, they're no match against a sufficiently-funded adversary. Contrast cryptography, where no amount of money or human effort could defeat, say, 256-bit symmetric encryption. The reason this matters is that if you accept that defeating physical defenses is always a matter of money, then you must next decide the attack cost that's sufficiently high to protect your assets. Then when you learn that the cost to defeat any hardware wallet, including Trezor, is already very high, you understand that we might as well be debating the merits of 255- vs. 256-bit encryption. (Note that this is not meant to draw an equivalence between hardware Bitcoin wallets and modern symmetric cryptography. There is a big difference. But not a difference that improves the infeasibility of mounting an attack against your Trezor with 25 BTC in it.)
      - londons_explore 9y ago
        If I had 250 BTC (half a million dollars), I would be quite confident that someone would try to steal it if a simple power supply glitching trick could extract it. Whereas if it is in a physically protected chip (like many credit card chips), I would feel rather safe knowing the tech and expertise to extract it costs more than half a million dollars.
        sowbug 9y ago
        We're in agreement on the general idea of a cost-benefit analysis for security, but your numbers are a bit off. 250BTC is worth over $1M USD (especially if you owned it as of Aug 1 and thus also have 250 Bitcoin Cash). Breaking into your house to steal a hardware wallet has a significant cost/risk in many people's minds. If someone is willing to break into your house, they're probably also willing to beat you senseless until you transfer them your bitcoin, because you surely value it less than your own life. That's why I think the cost to defeat hardware is high in general, but not especially relevant if your threat model includes targeted attacks.
- stickac 9y ago
  Not if the read protection level 2 is used. Which has been used since the beginning.
  - trezormcu 9y ago
    How true is this article? http://saleemrashid.com/2017/08/17/extracting-trezor-secrets-sram/ http://saleemrashid.com/2017/08/17/extracting-trezor-secrets...
ttam 9y ago
from the article: > Since Trezor has finally provided the hot-fix for this particular hack we can also fully disclose how it works. But they claim there are other similar hacks

londons_explore 9y ago

If the secret key is stored in a reversible way in a chip not designed against physical attacks, I fail to see how they could do a software fix? Sure they might have stopped anything getting copied to SRAM, but the data is still sitting there in flash ready to be read out by almost any method.

celticninja 9y ago
Article claims it works against unreleased Trezor V2 and software version 1.5.2 but Trezor say this is incorrect. So I would take the claims with a pinch of salt, especially they are charging almost $9k to download the software
sowbug 9y ago
Any secret must be stored "in a reversible way" or else it's useless.
- jjnoakes 9y ago
  Right, but then you should store it "in a chip designed against physical attacks", as the person you replied to mentioned.
  - sowbug 9y ago
    That isn't a panacea. Even though secure elements today have clever defenses against physical attack, they're no match against a sufficiently-funded adversary. Contrast cryptography, where no amount of money or human effort could defeat, say, 256-bit symmetric encryption. The reason this matters is that if you accept that defeating physical defenses is always a matter of money, then you must next decide the attack cost that's sufficiently high to protect your assets. Then when you learn that the cost to defeat any hardware wallet, including Trezor, is already very high, you understand that we might as well be debating the merits of 255- vs. 256-bit encryption. (Note that this is not meant to draw an equivalence between hardware Bitcoin wallets and modern symmetric cryptography. There is a big difference. But not a difference that improves the infeasibility of mounting an attack against your Trezor with 25 BTC in it.)
    - londons_explore 9y ago
      If I had 250 BTC (half a million dollars), I would be quite confident that someone would try to steal it if a simple power supply glitching trick could extract it. Whereas if it is in a physically protected chip (like many credit card chips), I would feel rather safe knowing the tech and expertise to extract it costs more than half a million dollars.
      - sowbug 9y ago
        We're in agreement on the general idea of a cost-benefit analysis for security, but your numbers are a bit off. 250BTC is worth over $1M USD (especially if you owned it as of Aug 1 and thus also have 250 Bitcoin Cash). Breaking into your house to steal a hardware wallet has a significant cost/risk in many people's minds. If someone is willing to break into your house, they're probably also willing to beat you senseless until you transfer them your bitcoin, because you surely value it less than your own life. That's why I think the cost to defeat hardware is high in general, but not especially relevant if your threat model includes targeted attacks.
stickac 9y ago
Not if the read protection level 2 is used. Which has been used since the beginning.
- trezormcu 9y ago
  How true is this article? http://saleemrashid.com/2017/08/17/extracting-trezor-secrets-sram/ http://saleemrashid.com/2017/08/17/extracting-trezor-secrets...

ttam 9y ago

from the article: > Since Trezor has finally provided the hot-fix for this particular hack we can also fully disclose how it works. But they claim there are other similar hacks