On 23/1/20 11:25 am, Artur Juraszek wrote:
Hi all,
While poking through Arch's package system, I noticed that despite its bad reputation, MD5 remains a default, and even some kind of a "recommendation", due to its presence in the example PKBUILDs, hashing algorithm for file integrity verification.
Is there a reason to not have it changed to a more future-proof one? I mean, at least for now, it seems good enough to protect before a so-called "2nd preimage attack", which is the primary concern in the classic file verification scenario, BUT:
a) given the huge size of AUR and its rather chaotic nature, it is not that hard to imagine _a_ malicious upstream which could try to sneak some nasty changes in its own files, with AUR maintainer not noticing anything - leveraging flaws which do exist and are quite well-explored even today.
b) it's already shown its weaknesses and it is not going to be any better - the only research direction is to found more (practical) attacks against MD5, so faster the change, fewer the people possibly affected in the future
Attaching a patch which, I think, replaces MD5 with SHA256 as a default completely - it's my first change in ABS-related code, though, so please do not hesitate to criticize if something's wrong ;]
This change is not happening. Any checksum is insecure when added to a PKGBUILD using "makepkg -g", which is all the default value does. The person writing a PKGBUILD needs to use what is provided upstream (or even a PGP signature), in which case the default in makepkg does not make a difference. Allan