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>If somebody inserts random odd generated crud in the middle of your source code, you will absolutely notice. Just as they noticed the intrusion on kernel.org

>If somebody inserts random odd generated crud in the middle of your source code, you will absolutely notice. Just as they noticed the intrusion on kernel.org servers after how long? edit: > If an attacker is pushing commits into your repository, you're long since toast on all possible security fronts, right? Sure, that's always true, in the worst case. Perfect security doesn't exist. But does it need to be an attacker? Couldn't it just happen that an important bugfix isn't recorded because the hash collides?

Dylan16807 10y ago
> Just as they noticed the intrusion on kernel.org servers after how long? It doesn't work retroactively. That crud needs to be there in the initial commit when it's accepted by multiple people. > Couldn't it just happen that an important bugfix isn't recorded because the hash collides? The hashes will never collide if there's no attacker. And that bugfix would have to have a blob of crud in the 'good' version, which would stick out like a sore thumb.
- posterboy 10y ago
  > It doesn't work retroactively. That crud needs to be there in the initial commit when it's accepted by multiple people. Do you assume that a proper preimage-attack would be needed? Instead, the good looking object could be committed, I guess after reading https://news.ycombinator.com/item?id=13721237 https://news.ycombinator.com/item?id=13721237 edit: > And that bugfix would have to have a blob of crud in the 'good' version Looking at google's POC, the colliding pdfs don't at all stick out (edit: but they are horribly contrived and you talked about code not blobs) [https://shattered.io/ https://shattered.io/] edit: thanks for your answer, it motivated me to learn a bit more. I'm still not sure if "never" is a rounding error, hyperbole (which would be ill advised talking to laymen), or actual fact (that source files due to the reduced entropy in byte patterns could in fact never ever collide, which I doubt).
  - Dylan16807 10y ago
    > the good looking object could be committed In source code there will be an obvious block of "hash was attacked here" crud in each file. The 'good looking' object will function non-maliciously, but it will be obvious that something is up. > I'm still not sure if "never" is a rounding error, hyperbole (which would be ill advised talking to laymen), or actual fact (that source files due to the reduced entropy in byte patterns could in fact never ever collide, which I doubt) "never" is to be read as "over a billion times more unlikely than all life on the planet suddenly being wiped out". It's not going to happen accidentally.

Dylan16807 10y ago

> Just as they noticed the intrusion on kernel.org servers after how long? It doesn't work retroactively. That crud needs to be there in the initial commit when it's accepted by multiple people. > Couldn't it just happen that an important bugfix isn't recorded because the hash collides? The hashes will never collide if there's no attacker. And that bugfix would have to have a blob of crud in the 'good' version, which would stick out like a sore thumb.

posterboy 10y ago
> It doesn't work retroactively. That crud needs to be there in the initial commit when it's accepted by multiple people. Do you assume that a proper preimage-attack would be needed? Instead, the good looking object could be committed, I guess after reading https://news.ycombinator.com/item?id=13721237 https://news.ycombinator.com/item?id=13721237 edit: > And that bugfix would have to have a blob of crud in the 'good' version Looking at google's POC, the colliding pdfs don't at all stick out (edit: but they are horribly contrived and you talked about code not blobs) [https://shattered.io/ https://shattered.io/] edit: thanks for your answer, it motivated me to learn a bit more. I'm still not sure if "never" is a rounding error, hyperbole (which would be ill advised talking to laymen), or actual fact (that source files due to the reduced entropy in byte patterns could in fact never ever collide, which I doubt).
- Dylan16807 10y ago
  > the good looking object could be committed In source code there will be an obvious block of "hash was attacked here" crud in each file. The 'good looking' object will function non-maliciously, but it will be obvious that something is up. > I'm still not sure if "never" is a rounding error, hyperbole (which would be ill advised talking to laymen), or actual fact (that source files due to the reduced entropy in byte patterns could in fact never ever collide, which I doubt) "never" is to be read as "over a billion times more unlikely than all life on the planet suddenly being wiped out". It's not going to happen accidentally.