On May 28, 2013, at 3:39 PM, Michael Hall <mik3h...@gmail.com> wrote: > On May 28, 2013, at 5:27 PM, Michael Hall wrote: >> I thought I saw SHA-1 being used as a general purpose hash function >> somewhere sort of surprising recently but I'm not remembering exactly where. > > Ah, sorry to reply to my own but maybe this was it… > > https://news.ycombinator.com/item?id=4036878 > SHA-1is still used in applications such as git as a general purpose hash > function. > > Not this particular article where I saw it but I recently signed up on git > and think I may of seen it's use then.
For this sort of use I expect SHA-1 is chosen in part because it computes a bigger value than a typical hash-table hash. (160 bits for SHA-1 and 256+ for SHA-2, versus 32 or 64 for a typical hash table.) git in particular wants an ID that is as globally unique as possible so 64 bits is not enough, is computing a small number of hashes so the extra per-hash setup time for a cryptographic hash is less important, and is probably I/O bound anyway so the extra CPU time of a cryptographic hash is less important. -- Greg Parker gpar...@apple.com Runtime Wrangler _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
