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"But even software ARX gets into trouble when protection against power or electromagnetic analysis is a threat." - I still don't get this. If attackers have ph

by powera 9y ago

"But even software ARX gets into trouble when protection against power or electromagnetic analysis is a threat." - I still don't get this. If attackers have physical access to your machine, you should consider it compromised. Switching from SHA2 to SHA3 is irrelevant.

cakoose 9y ago
EM radiation and power draw patterns from your device can leak information about what the device is doing. The NSA takes this stuff seriously: https://en.wikipedia.org/wiki/Tempest_(codename) https://en.wikipedia.org/wiki/Tempest_(codename) There are situations where an attacker doesn't have full physical access to a device but can still observe EM radiation. For example, someone sitting next to you with an EM receiver, observing emissions from your 2FA token.
xoa 9y ago
>If attackers have physical access to your machine, you should consider it compromised. This bit of "wisdom" dates back to the very, very old days when security wrt computers was primarily a consideration for servers in physically secure locations. It is utterly obsolete, and every more so with each passing year. HSMs, CPU-level trusted modules, etc. have long since been a thing, as for that matter has even basic software measures like FDE. All exist in part or in whole to help with certain kinds of physical access. It is not in fact straight forward, reliable or for most attackers even possible to pull bits directly off a well designed physically secure chip with an STM or whatever. I don't think looking back the actual weaknesses in MD5/SHA were related to ARX, but I'm not equipped to judge whether ARX might introduce TEMPEST related issues. It is not a fundamentally invalid consideration however. Side-channel attacks are one of the most classic and fiendishly difficult issues in cryptography and EM emissions are a known domain problem that can't always be solved merely via use of shielding. It's better even then to have it considered right down the primitive level. Layers and all that.
aidenn0 9y ago
There are plenty of real-world examples that are hardened against physical access; smartcards are the most ubiquitous example. You ought not be able to recover key material from a smart card just by analyzing the power-draw, or you could skim chips just as easily as stripes.

by powera 9y ago

cakoose 9y ago

EM radiation and power draw patterns from your device can leak information about what the device is doing. The NSA takes this stuff seriously: https://en.wikipedia.org/wiki/Tempest_(codename) https://en.wikipedia.org/wiki/Tempest_(codename) There are situations where an attacker doesn't have full physical access to a device but can still observe EM radiation. For example, someone sitting next to you with an EM receiver, observing emissions from your 2FA token.

xoa 9y ago

>If attackers have physical access to your machine, you should consider it compromised. This bit of "wisdom" dates back to the very, very old days when security wrt computers was primarily a consideration for servers in physically secure locations. It is utterly obsolete, and every more so with each passing year. HSMs, CPU-level trusted modules, etc. have long since been a thing, as for that matter has even basic software measures like FDE. All exist in part or in whole to help with certain kinds of physical access. It is not in fact straight forward, reliable or for most attackers even possible to pull bits directly off a well designed physically secure chip with an STM or whatever. I don't think looking back the actual weaknesses in MD5/SHA were related to ARX, but I'm not equipped to judge whether ARX might introduce TEMPEST related issues. It is not a fundamentally invalid consideration however. Side-channel attacks are one of the most classic and fiendishly difficult issues in cryptography and EM emissions are a known domain problem that can't always be solved merely via use of shielding. It's better even then to have it considered right down the primitive level. Layers and all that.

aidenn0 9y ago

There are plenty of real-world examples that are hardened against physical access; smartcards are the most ubiquitous example. You ought not be able to recover key material from a smart card just by analyzing the power-draw, or you could skim chips just as easily as stripes.