3 ms·
Soldering ram is helpful for preventing people cooling the ram and removing it to attempt to copy private encryption keys
by mavhc 8y ago
Soldering ram is helpful for preventing people cooling the ram and removing it to attempt to copy private encryption keys
- JasonFruit 8y agoYes, I can't count the number of times soldered RAM has saved me from this. Can you count to zero?
- pbhjpbhj 8y agoCouldn't the 3 people in the World who need that just dob some epoxy on there?
- hedora 8y agoModern intel (and probably most other) boards use hardware scramblers for other reasons (storing all zeros or all ones causes signal integrity issues / current spikes), and secure the scrambling routine with a different code at each boot. So, unless I’m mistaken, cooling the ram and moving to another doesn’t work any more.
- eitland 8y agoSeriously interesting. Any pointers?
- Kliment 8y agoThere are two types of scrambling here - one is the bitswapping and byteswapping that you use to make DDR3/4 routing possible. The other is the whitening function for high speed data that ensures you don't have long sequences of the same value without a transition. The latter is a simple pseudorandom scrambler with a fixed random seed generated at boot. It is not cryptographically secure. The former is a simple substitution and quite easy to reverse (and trivial if you have either a schematic or a board to reverse). Both are deterministic and extremely vulnerable to known plaintext attacks. This is not a security feature. Source: I'm working on a DDR4 layout right now, and the memory controller scrambling and swapping functions are documented in publically-available intel datasheets (for example, see https://www.intel.com/content/dam/www/public/us/en/documents/datasheets/7th-gen-core-family-mobile-u-y-processor-lines-datasheet-vol-1.pdf https://www.intel.com/content/dam/www/public/us/en/documents... sections 2.1.6 and 2.1.8)