5 ms·

There's very few solutions to "physical access = game over".

xyzzyz 8y ago
There's a whole industry that's doing just that. Look up Hardware Security Modules. It is likely that you have a security device like that in the machine you are using right now (a Trusted Platform Module). People didn't simply threw their hands up, there are solutions for various problems in this space, with physical access being present in the threat model.
- gruez 8y ago
  >It is likely that you have a security device like that in the machine you are using right now funny you say that, because TPMs aren't actually mandated to be tamper resistant, only tamper evident[1]. what this means is that you won't be able to extract the keys without destroying the device, but if you delid the chip and probe it, you can probably extract the keys. I suspect it's the same with other HSMs you see in everyday life (smart cards, smartphone with trustzone, etc.). [1] sorry i don't have a better source: https://media.ccc.de/v/32c3-7343-beyond_anti_evil_maid https://media.ccc.de/v/32c3-7343-beyond_anti_evil_maid
  - borgmace 8y ago
    Not true with real HSMs with FIPS 140-2 Level3+ The key material is protected from extraction.
  - throwaway91345 8y ago
    You are mistaken. TPMs these days are as tamper resistant as it gets, and a manufacturer would have severe difficulty selling one without an independent security certification proving that it actually is. Which means a state-of-the-art security lab with highly skilled experts and millions worth of specialized equipment attempts to break the chip for an extended amount of time, trying all sorts of known attacks, utilizing extensive access to information on chip internals that a real-life attacker normally would not have, _and in effect fails to break it nonetheless_. Google for 'Tarnovsky attack' and spend an evening watching thrilling videos to see to which lengths a top-notch adversary needed to go to break into these chips even in 2010-13. As for the chances in 2018, draw your own conclusions.
  - throwawaymath 8y ago
    Smart cards are tamper resistant by definition. See https://people.cs.uchicago.edu/~dinoj/smartcard/security.html https://people.cs.uchicago.edu/~dinoj/smartcard/security.htm....
    - gruez 8y ago
      i did a quick skim of the article for "resist" and couldn't find anything to back your claim. all the article says is that smart cards have better security because they're isolated from the host (which is a security measure, but doesn't say anything about physical tampering resistance), and that some smart cards have tamper resistance built in.
      - dfox 8y ago
        For true tamper resistance you need to have some way to actually detect tampering and erase the secrets, which usually leads to some battery-backed SRAM and associated tamper response circuitry. While there are some smart cards and smartcard-like HSMs (Fortezza comes to mind, but it uses the battery primarily for integrated RTC and seems to not contain any tamper detection mechanism) with integrated battery, common smartcards does not have battery.
      - throwawaymath 8y ago
        If you'd like more evidence of what I'm saying, read Smart Cards, Tokens, Security and Applications or Secure Smart Embedded Devices, Platforms and Applications. Both are graduate textbooks covering smart card design and development. The term "smart card" is frequently misused in popular nomenclature. As a technical term, it refers specifically to contact or contact-less (like NFC) cards with an embedded chip which are, at minimum, physically tamper resistant. For example, a typical credit card is not a smart card. A SIM card is a smart card (or token). Tamper resistant does not imply tamper proof, which can also be a source of confusion.
  - closeparen 8y ago
    There are different devices for different security needs. When you're protecting the key material for a revocable certificate, tamper evidence is sufficient: when you detect tampering, revoke the certificate. FIPS 140-2 Level 2 devices provide this level of security and are common in end-user credentials like smart card badges and the TPMs in laptops. FIPS 140-2 Level 3 provides tamper resistance meant to defeat most attacks, that's the device you'd want to use to protect a root of trust or important encryption key. Level 4 devices are meant to hold up against as many attacks as possible, even when the attacker can push the physical operating environment far outside normal bounds (solvents, liquid nitrogen, extreme heat, etc).
khedoros1 8y ago
There's no absolute solution. But that doesn't mean that they shouldn't have protected against well-understood classes of attack. Vulnerability to an attack that needs 5 minutes of physical access would be much better than vulnerability to an attack that needs 30 seconds.

There's a whole industry that's doing just that. Look up Hardware Security Modules. It is likely that you have a security device like that in the machine you are using right now (a Trusted Platform Module). People didn't simply threw their hands up, there are solutions for various problems in this space, with physical access being present in the threat model.

gruez 8y ago
>It is likely that you have a security device like that in the machine you are using right now funny you say that, because TPMs aren't actually mandated to be tamper resistant, only tamper evident[1]. what this means is that you won't be able to extract the keys without destroying the device, but if you delid the chip and probe it, you can probably extract the keys. I suspect it's the same with other HSMs you see in everyday life (smart cards, smartphone with trustzone, etc.). [1] sorry i don't have a better source: https://media.ccc.de/v/32c3-7343-beyond_anti_evil_maid https://media.ccc.de/v/32c3-7343-beyond_anti_evil_maid
- borgmace 8y ago
  Not true with real HSMs with FIPS 140-2 Level3+ The key material is protected from extraction.
- throwaway91345 8y ago
  You are mistaken. TPMs these days are as tamper resistant as it gets, and a manufacturer would have severe difficulty selling one without an independent security certification proving that it actually is. Which means a state-of-the-art security lab with highly skilled experts and millions worth of specialized equipment attempts to break the chip for an extended amount of time, trying all sorts of known attacks, utilizing extensive access to information on chip internals that a real-life attacker normally would not have, _and in effect fails to break it nonetheless_. Google for 'Tarnovsky attack' and spend an evening watching thrilling videos to see to which lengths a top-notch adversary needed to go to break into these chips even in 2010-13. As for the chances in 2018, draw your own conclusions.
- throwawaymath 8y ago
  Smart cards are tamper resistant by definition. See https://people.cs.uchicago.edu/~dinoj/smartcard/security.html https://people.cs.uchicago.edu/~dinoj/smartcard/security.htm....
  - gruez 8y ago
    i did a quick skim of the article for "resist" and couldn't find anything to back your claim. all the article says is that smart cards have better security because they're isolated from the host (which is a security measure, but doesn't say anything about physical tampering resistance), and that some smart cards have tamper resistance built in.
    - dfox 8y ago
      For true tamper resistance you need to have some way to actually detect tampering and erase the secrets, which usually leads to some battery-backed SRAM and associated tamper response circuitry. While there are some smart cards and smartcard-like HSMs (Fortezza comes to mind, but it uses the battery primarily for integrated RTC and seems to not contain any tamper detection mechanism) with integrated battery, common smartcards does not have battery.
    - throwawaymath 8y ago
      If you'd like more evidence of what I'm saying, read Smart Cards, Tokens, Security and Applications or Secure Smart Embedded Devices, Platforms and Applications. Both are graduate textbooks covering smart card design and development. The term "smart card" is frequently misused in popular nomenclature. As a technical term, it refers specifically to contact or contact-less (like NFC) cards with an embedded chip which are, at minimum, physically tamper resistant. For example, a typical credit card is not a smart card. A SIM card is a smart card (or token). Tamper resistant does not imply tamper proof, which can also be a source of confusion.
- closeparen 8y ago
  There are different devices for different security needs. When you're protecting the key material for a revocable certificate, tamper evidence is sufficient: when you detect tampering, revoke the certificate. FIPS 140-2 Level 2 devices provide this level of security and are common in end-user credentials like smart card badges and the TPMs in laptops. FIPS 140-2 Level 3 provides tamper resistance meant to defeat most attacks, that's the device you'd want to use to protect a root of trust or important encryption key. Level 4 devices are meant to hold up against as many attacks as possible, even when the attacker can push the physical operating environment far outside normal bounds (solvents, liquid nitrogen, extreme heat, etc).

khedoros1 8y ago

There's no absolute solution. But that doesn't mean that they shouldn't have protected against well-understood classes of attack. Vulnerability to an attack that needs 5 minutes of physical access would be much better than vulnerability to an attack that needs 30 seconds.