Feature request: improved build-id generation

Andy Lutomirski luto@kernel.org
Thu Mar 15 17:03:00 GMT 2018


On Thu, Mar 15, 2018 at 7:45 AM, Cary Coutant <ccoutant@gmail.com> wrote:
>> Cryptography has nothing whatsoever to do with my request.  I think
>> that the construction should be set up to make it exceedingly unlikely
>> to generate *accidental* collisions, and, since it's so easy to make
>> it effectively impossible to generate even intentional collisions, I
>> think that's the right approach.  If the binutils crowd would prefer
>> to add --build-it-key or equivalent without adding a new hash
>> function, i'd be okay with that, but I think it would be silly.
>
> You're making it sound like what you're asking for will require a new
> from-the-ground-up feature, rather than just an option to inject
> additional data into the hash computation.

Then I'm stating my case poorly.  I want a way to inject additional
data into the has computation.

> SHA-2 is 50% slower than
> SHA-1 (it's even slower than MD-5 according to the benchmarks I've
> seen), and, as far as I can tell, it provides no additional value for
> our purposes. SHA-1 may not be the best or the fastest, but it seems
> to be a good balance. As I said before, I wouldn't mind adding a new
> hash function if it provides value, but that seems to be completely
> orthogonal to your request.

Fair enough.  FWIW, if the performance impact is measurable, than all
the SHA variants are the wrong choices and you should probably use one
of the Blake2 hashes or even SipHash.



More information about the Binutils mailing list