From: Ian Jackson <ijackson@chiark.greenend.org.uk> To: Linus Torvalds <torvalds@linux-foundation.org> Cc: Jonathan Nieder <jrnieder@gmail.com>, Git Mailing List <git@vger.kernel.org>, Stefan Beller <sbeller@google.com>, bmwill@google.com, Jonathan Tan <jonathantanmy@google.com>, Jeff King <peff@peff.net> Subject: Re: RFC: Another proposed hash function transition plan Date: Wed, 8 Mar 2017 11:20:17 +0000 Message-ID: <22719.59633.269164.986923@chiark.greenend.org.uk> (raw) In-Reply-To: <CA+55aFyyi0vBBApf9grYQzF2PRZMjtCzkB4LzYvLpqQ-Z7QfJQ@mail.gmail.com> Linus Torvalds writes ("Re: RFC: Another proposed hash function transition plan"): > Also, since 256 isn't evenly divisible by 6, and because you'd want > some way to explictly disambiguate the new hashes, the rule *could* be > that the ASCII representation of a new hash is the base64 encoding of > the 258-bit value that has "10" prepended to it as padding. > > That way the first character of the hash would be guaranteed to not be > a hex digit, because it would be in the range [g-v] (indexes 32..47). We should arrange for this to be an uppercase, not a lowercase, letter, for the reasons I explained in my own proposal. To summarise: It would be undesirable to further increase the overlap between object names and ref names. Few people use uppercase in ref names because of the case-insensitive filesystem problem; so object names starting with uppercase ascii are distinct from most object names. > Of course, having written that, I now realize how it would cause > problems for the usual shit-for-brains case-insensitive filesystems. > So I guess base64 encoding doesn't work well for that reason. AFAIAA object names occur in publicly-visible filenames only in notes tree objects, which are manipulated by git internally and do not necessarily need to appear in the filesystem. The filenames in .git/objects/ can be in whatever encoding we like, so are not an obstacle. Ian. -- Ian Jackson <ijackson@chiark.greenend.org.uk> These opinions are my own. If I emailed you from an address @fyvzl.net or @evade.org.uk, that is a private address which bypasses my fierce spamfilter.
next prev parent reply index Thread overview: 111+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-03-04 1:12 Jonathan Nieder 2017-03-05 2:35 ` Linus Torvalds 2017-03-06 0:26 ` brian m. carlson 2017-03-06 18:24 ` Brandon Williams 2017-06-15 10:30 ` Which hash function to use, was " Johannes Schindelin 2017-06-15 11:05 ` Mike Hommey 2017-06-15 13:01 ` Jeff King 2017-06-15 16:30 ` Ævar Arnfjörð Bjarmason 2017-06-15 19:34 ` Johannes Schindelin 2017-06-15 21:59 ` Adam Langley 2017-06-15 22:41 ` brian m. carlson 2017-06-15 23:36 ` Ævar Arnfjörð Bjarmason 2017-06-16 0:17 ` brian m. carlson 2017-06-16 6:25 ` Ævar Arnfjörð Bjarmason 2017-06-16 13:24 ` Johannes Schindelin 2017-06-16 17:38 ` Adam Langley 2017-06-16 20:52 ` Junio C Hamano 2017-06-16 21:12 ` Junio C Hamano 2017-06-16 21:24 ` Jonathan Nieder 2017-06-16 21:39 ` Ævar Arnfjörð Bjarmason 2017-06-16 20:42 ` Jeff King 2017-06-19 9:26 ` Johannes Schindelin 2017-06-15 21:10 ` Mike Hommey 2017-06-16 4:30 ` Jeff King 2017-06-15 17:36 ` Brandon Williams 2017-06-15 19:20 ` Junio C Hamano 2017-06-15 19:13 ` Jonathan Nieder 2017-03-07 0:17 ` RFC v3: " Jonathan Nieder 2017-03-09 19:14 ` Shawn Pearce 2017-03-09 20:24 ` Jonathan Nieder 2017-03-10 19:38 ` Jeff King 2017-03-10 19:55 ` Jonathan Nieder 2017-09-28 4:43 ` [PATCH v4] technical doc: add a design doc for hash function transition Jonathan Nieder 2017-09-29 6:06 ` Junio C Hamano 2017-09-29 8:09 ` Junio C Hamano 2017-09-29 17:34 ` Jonathan Nieder 2017-10-02 8:25 ` Junio C Hamano 2017-10-02 19:41 ` Jason Cooper 2017-10-02 9:02 ` Junio C Hamano 2017-10-02 19:23 ` Jason Cooper 2017-10-03 5:40 ` Junio C Hamano 2017-10-03 13:08 ` Jason Cooper 2017-10-04 1:44 ` Junio C Hamano 2017-09-06 6:28 ` RFC v3: Another proposed hash function transition plan Junio C Hamano 2017-09-08 2:40 ` Junio C Hamano 2017-09-08 3:34 ` Jeff King 2017-09-11 18:59 ` Brandon Williams 2017-09-13 12:05 ` Johannes Schindelin 2017-09-13 13:43 ` demerphq 2017-09-13 22:51 ` Jonathan Nieder 2017-09-14 18:26 ` Johannes Schindelin 2017-09-14 18:40 ` Jonathan Nieder 2017-09-14 22:09 ` Johannes Schindelin 2017-09-13 23:30 ` Linus Torvalds 2017-09-14 18:45 ` Johannes Schindelin 2017-09-18 12:17 ` Gilles Van Assche 2017-09-18 22:16 ` Johannes Schindelin 2017-09-19 16:45 ` Gilles Van Assche 2017-09-29 13:17 ` Johannes Schindelin 2017-09-29 14:54 ` Joan Daemen 2017-09-29 22:33 ` Johannes Schindelin 2017-09-30 22:02 ` Joan Daemen 2017-10-02 14:26 ` Johannes Schindelin 2017-09-18 22:25 ` Jonathan Nieder 2017-09-26 17:05 ` Jason Cooper 2017-09-26 22:11 ` Johannes Schindelin 2017-09-26 22:25 ` [PATCH] technical doc: add a design doc for hash function transition Stefan Beller 2017-09-26 23:38 ` Jonathan Nieder 2017-09-26 23:51 ` RFC v3: Another proposed hash function transition plan Jonathan Nieder 2017-10-02 14:54 ` Jason Cooper 2017-10-02 16:50 ` Brandon Williams 2017-10-02 14:00 ` Jason Cooper 2017-10-02 17:18 ` Linus Torvalds 2017-10-02 19:37 ` Jeff King 2017-09-13 16:30 ` Jonathan Nieder 2017-09-13 21:52 ` Junio C Hamano 2017-09-13 22:07 ` Stefan Beller 2017-09-13 22:18 ` Jonathan Nieder 2017-09-14 2:13 ` Junio C Hamano 2017-09-14 15:23 ` Johannes Schindelin 2017-09-14 15:45 ` demerphq 2017-09-14 22:06 ` Johannes Schindelin 2017-09-13 22:15 ` Junio C Hamano 2017-09-13 22:27 ` Jonathan Nieder 2017-09-14 2:10 ` Junio C Hamano 2017-09-14 12:39 ` Johannes Schindelin 2017-09-14 16:36 ` Brandon Williams 2017-09-14 18:49 ` Jonathan Nieder 2017-09-15 20:42 ` Philip Oakley 2017-03-05 11:02 ` RFC: " David Lang [not found] ` <CA+dhYEXHbQfJ6KUB1tWS9u1MLEOJL81fTYkbxu4XO-i+379LPw@mail.gmail.com> 2017-03-06 9:43 ` Jeff King 2017-03-06 23:40 ` Jonathan Nieder 2017-03-07 0:03 ` Mike Hommey 2017-03-06 8:43 ` Jeff King 2017-03-06 18:39 ` Jonathan Tan 2017-03-06 19:22 ` Linus Torvalds 2017-03-06 19:59 ` Brandon Williams 2017-03-06 21:53 ` Junio C Hamano 2017-03-07 8:59 ` Jeff King 2017-03-06 18:43 ` Junio C Hamano 2017-03-07 18:57 ` Ian Jackson 2017-03-07 19:15 ` Linus Torvalds 2017-03-08 11:20 ` Ian Jackson [this message] 2017-03-08 15:37 ` Johannes Schindelin 2017-03-08 15:40 ` Johannes Schindelin 2017-03-20 5:21 ` Use base32? Jason Hennessey 2017-03-20 5:58 ` Michael Steuer 2017-03-20 8:05 ` Jacob Keller 2017-03-21 3:07 ` Michael Steuer 2017-03-13 9:24 ` RFC: Another proposed hash function transition plan The Keccak Team 2017-03-13 17:48 ` Jonathan Nieder 2017-03-13 18:34 ` ankostis 2017-03-17 11:07 ` Johannes Schindelin
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