5 ms·

You're a moron, Torvalds, not a cryptographer

7 points by nkurz 11y ago

Arnt 11y ago
Linus also wrote that "SHA-1, as far as Git is concerned, isn't even a security feature. It's purely a consistency check. The security parts are elsewhere, so a lot of people assume that since Git uses SHA-1 and SHA-1 is used for cryptographically secure stuff, they think that, OK, it's a huge security feature. It has nothing at all to do with security, it's just the best hash you can get." (It's not security because it's stored together with the data. An attacker who can corrupt a particular patch has enough access to corrupt the rest of the same file. It's not meant to defend against an attacker, merely to detect accidental corruption.)
- samuellb 11y ago
  That's true, but the format of signed tags will need to change in one way or another. What we could do is to have a "shadow" tree which is built using a stronger hash algorithm (e.g. SHA256), and which is used for signing history. The shadow tree would be identical to the real tree except for the hashes and references to hashes.
Tiquor 11y ago
The author seems to be missing a bit of Linus' point. It seems that the point Linus is making is that a collision along with the underlying data being meaningful is orders of magnitude harder than the collission, or produces easily detectable abberations. I'm not a cryptographic expert either but the author seems to be thinking more in a world of passwords where the underlying data often remains unknown. I think Linus is being somewhat pragmatic too and basically saying that if you think this is a problem then the whole thing is a house of cards.
sgdread 11y ago
Very interesting way to start a blogging career: never learn about subject (SHA-1 and it's role in git), call creator moron and then rant on security issues with SHA-1 without realizing SHA-1 is just hash and has no security function in git (at least in context Linus posted his reply 10 years ago).
- alexandrerond 11y ago
  well, isn't it nice when a blog uncovers so much from its author right from the first post?
- agnivade 11y ago
  Damn, I didn't realise Linus' reply was over 10 years ago !

7 points by nkurz 11y ago

Arnt 11y ago

Linus also wrote that "SHA-1, as far as Git is concerned, isn't even a security feature. It's purely a consistency check. The security parts are elsewhere, so a lot of people assume that since Git uses SHA-1 and SHA-1 is used for cryptographically secure stuff, they think that, OK, it's a huge security feature. It has nothing at all to do with security, it's just the best hash you can get." (It's not security because it's stored together with the data. An attacker who can corrupt a particular patch has enough access to corrupt the rest of the same file. It's not meant to defend against an attacker, merely to detect accidental corruption.)

samuellb 11y ago
That's true, but the format of signed tags will need to change in one way or another. What we could do is to have a "shadow" tree which is built using a stronger hash algorithm (e.g. SHA256), and which is used for signing history. The shadow tree would be identical to the real tree except for the hashes and references to hashes.

Tiquor 11y ago

The author seems to be missing a bit of Linus' point. It seems that the point Linus is making is that a collision along with the underlying data being meaningful is orders of magnitude harder than the collission, or produces easily detectable abberations. I'm not a cryptographic expert either but the author seems to be thinking more in a world of passwords where the underlying data often remains unknown. I think Linus is being somewhat pragmatic too and basically saying that if you think this is a problem then the whole thing is a house of cards.

sgdread 11y ago

Very interesting way to start a blogging career: never learn about subject (SHA-1 and it's role in git), call creator moron and then rant on security issues with SHA-1 without realizing SHA-1 is just hash and has no security function in git (at least in context Linus posted his reply 10 years ago).

alexandrerond 11y ago
well, isn't it nice when a blog uncovers so much from its author right from the first post?
agnivade 11y ago
Damn, I didn't realise Linus' reply was over 10 years ago !