From: "George Spelvin" <linux@sciencehorizons.net> To: ak@linux.intel.com, davem@davemloft.net, David.Laight@aculab.com, ebiggers3@gmail.com, hannes@stressinduktion.org, Jason@zx2c4.com, jeanphilippe.aumasson@gmail.com, kernel-hardening@lists.openwall.com, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, linux@sciencehorizons.net, luto@amacapital.net, netdev@vger.kernel.org, tom@herbertland.com, torvalds@linux-foundation.org, tytso@mit.edu, vegard.nossum@gmail.com Cc: djb@cr.yp.to Subject: Re: [PATCH v5 1/4] siphash: add cryptographically secure PRF Date: 15 Dec 2016 18:28:40 -0500 [thread overview] Message-ID: <20161215232840.22459.qmail@ns.sciencehorizons.net> (raw) In-Reply-To: <CAGiyFdfmiCMyHvAg=5sGh8KjBBrF0Wb4Qf=JLzJqUAx4yFSS3Q@mail.gmail.com> > If a halved version of SipHash can bring significant performance boost > (with 32b words instead of 64b words) with an acceptable security level > (64-bit enough?) then we may design such a version. I was thinking if the key could be pushed to 80 bits, that would be nice, but honestly 64 bits is fine. This is DoS protection, and while it's possible to brute-force a 64 bit secret, there are more effective (DDoS) attacks possible for the same cost. (I'd suggest a name of "HalfSipHash" to convey the reduced security effectively.) > Regarding output size, are 64 bits sufficient? As a replacement for jhash, 32 bits are sufficient. It's for indexing an in-memory hash table on a 32-bit machine. (When you're done thinking about this, as a matter of personal interest I'd love a hash expert's opinion on https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=2a18da7a9c7886f1c7307f8d3f23f24318583f03 and https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=8387ff2577eb9ed245df9a39947f66976c6bcd02 which is a non-cryptographic hash function of novel design that's inspired by SipHash.)
WARNING: multiple messages have this Message-ID (diff)
From: "George Spelvin" <linux@sciencehorizons.net> To: ak@linux.intel.com, davem@davemloft.net, David.Laight@aculab.com, ebiggers3@gmail.com, hannes@stressinduktion.org, Jason@zx2c4.com, jeanphilippe.aumasson@gmail.com, kernel-hardening@lists.openwall.com, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, linux@sciencehorizons.net, luto@amacapital.net, netdev@vger.kernel.org, tom@herbertland.com, torvalds@linux-foundation.org, tytso@mit.edu, vegard.nossum@gmail.com Cc: djb@cr.yp.to Subject: [kernel-hardening] Re: [PATCH v5 1/4] siphash: add cryptographically secure PRF Date: 15 Dec 2016 18:28:40 -0500 [thread overview] Message-ID: <20161215232840.22459.qmail@ns.sciencehorizons.net> (raw) In-Reply-To: <CAGiyFdfmiCMyHvAg=5sGh8KjBBrF0Wb4Qf=JLzJqUAx4yFSS3Q@mail.gmail.com> > If a halved version of SipHash can bring significant performance boost > (with 32b words instead of 64b words) with an acceptable security level > (64-bit enough?) then we may design such a version. I was thinking if the key could be pushed to 80 bits, that would be nice, but honestly 64 bits is fine. This is DoS protection, and while it's possible to brute-force a 64 bit secret, there are more effective (DDoS) attacks possible for the same cost. (I'd suggest a name of "HalfSipHash" to convey the reduced security effectively.) > Regarding output size, are 64 bits sufficient? As a replacement for jhash, 32 bits are sufficient. It's for indexing an in-memory hash table on a 32-bit machine. (When you're done thinking about this, as a matter of personal interest I'd love a hash expert's opinion on https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=2a18da7a9c7886f1c7307f8d3f23f24318583f03 and https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=8387ff2577eb9ed245df9a39947f66976c6bcd02 which is a non-cryptographic hash function of novel design that's inspired by SipHash.)
next prev parent reply other threads:[~2016-12-15 23:28 UTC|newest] Thread overview: 182+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-12-15 20:29 [PATCH v5 0/4] The SipHash Patchset Jason A. Donenfeld 2016-12-15 20:29 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-15 20:30 ` [PATCH v5 1/4] siphash: add cryptographically secure PRF Jason A. Donenfeld 2016-12-15 20:30 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-15 22:42 ` George Spelvin 2016-12-15 22:42 ` [kernel-hardening] " George Spelvin 2016-12-15 23:00 ` Jean-Philippe Aumasson 2016-12-15 23:00 ` [kernel-hardening] " Jean-Philippe Aumasson 2016-12-15 23:28 ` George Spelvin [this message] 2016-12-15 23:28 ` George Spelvin 2016-12-16 17:06 ` David Laight 2016-12-16 17:06 ` [kernel-hardening] " David Laight 2016-12-16 17:06 ` David Laight 2016-12-16 17:09 ` Jason A. Donenfeld 2016-12-16 17:09 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-16 17:09 ` Jason A. Donenfeld 2016-12-16 3:46 ` George Spelvin 2016-12-16 3:46 ` [kernel-hardening] " George Spelvin 2016-12-16 8:08 ` Jean-Philippe Aumasson 2016-12-16 8:08 ` [kernel-hardening] " Jean-Philippe Aumasson 2016-12-16 12:39 ` Jason A. Donenfeld 2016-12-16 12:39 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-16 13:22 ` Jean-Philippe Aumasson 2016-12-16 13:22 ` [kernel-hardening] " Jean-Philippe Aumasson 2016-12-16 15:51 ` Jason A. Donenfeld 2016-12-16 15:51 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-16 17:36 ` George Spelvin 2016-12-16 17:36 ` [kernel-hardening] " George Spelvin 2016-12-16 18:00 ` Jason A. Donenfeld 2016-12-16 18:00 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-16 20:17 ` George Spelvin 2016-12-16 20:17 ` [kernel-hardening] " George Spelvin 2016-12-16 20:43 ` Theodore Ts'o 2016-12-16 20:43 ` [kernel-hardening] " Theodore Ts'o 2016-12-16 22:13 ` George Spelvin 2016-12-16 22:13 ` [kernel-hardening] " George Spelvin 2016-12-16 22:15 ` Andy Lutomirski 2016-12-16 22:15 ` [kernel-hardening] " Andy Lutomirski 2016-12-16 22:15 ` Andy Lutomirski 2016-12-16 22:18 ` Jason A. Donenfeld 2016-12-16 22:18 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-16 23:44 ` George Spelvin 2016-12-16 23:44 ` [kernel-hardening] " George Spelvin 2016-12-17 1:39 ` Jason A. Donenfeld 2016-12-17 1:39 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-17 2:15 ` George Spelvin 2016-12-17 2:15 ` [kernel-hardening] " George Spelvin 2016-12-17 15:41 ` Theodore Ts'o 2016-12-17 15:41 ` [kernel-hardening] " Theodore Ts'o 2016-12-17 16:14 ` Jeffrey Walton 2016-12-17 16:14 ` [kernel-hardening] " Jeffrey Walton 2016-12-19 17:21 ` Jason A. Donenfeld 2016-12-17 12:42 ` George Spelvin 2016-12-17 12:42 ` [kernel-hardening] " George Spelvin 2016-12-16 20:39 ` Jason A. Donenfeld 2016-12-16 20:39 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-16 19:47 ` Tom Herbert 2016-12-16 19:47 ` [kernel-hardening] " Tom Herbert 2016-12-16 20:41 ` George Spelvin 2016-12-16 20:41 ` [kernel-hardening] " George Spelvin 2016-12-16 20:57 ` Tom Herbert 2016-12-16 20:57 ` [kernel-hardening] " Tom Herbert 2016-12-16 20:44 ` Daniel Micay 2016-12-16 20:44 ` [kernel-hardening] " Daniel Micay 2016-12-16 21:09 ` Jason A. Donenfeld 2016-12-17 15:21 ` George Spelvin 2016-12-17 15:21 ` [kernel-hardening] " George Spelvin 2016-12-19 14:14 ` David Laight 2016-12-19 14:14 ` [kernel-hardening] " David Laight 2016-12-19 14:14 ` David Laight 2016-12-19 18:10 ` George Spelvin 2016-12-19 18:10 ` [kernel-hardening] " George Spelvin 2016-12-19 20:18 ` Jean-Philippe Aumasson 2016-12-19 20:18 ` [kernel-hardening] " Jean-Philippe Aumasson 2016-12-16 2:14 ` kbuild test robot 2016-12-16 2:14 ` [kernel-hardening] " kbuild test robot 2016-12-17 14:55 ` Jeffrey Walton 2016-12-17 14:55 ` [kernel-hardening] " Jeffrey Walton 2016-12-19 17:08 ` Jason A. Donenfeld 2016-12-19 17:08 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-19 17:19 ` Jean-Philippe Aumasson 2016-12-19 17:19 ` [kernel-hardening] " Jean-Philippe Aumasson 2016-12-15 20:30 ` [PATCH v5 2/4] siphash: add Nu{32,64} helpers Jason A. Donenfeld 2016-12-15 20:30 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-16 10:39 ` David Laight 2016-12-16 10:39 ` [kernel-hardening] " David Laight 2016-12-16 10:39 ` David Laight 2016-12-16 15:44 ` George Spelvin 2016-12-16 15:44 ` [kernel-hardening] " George Spelvin 2016-12-15 20:30 ` [PATCH v5 3/4] secure_seq: use SipHash in place of MD5 Jason A. Donenfeld 2016-12-15 20:30 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-16 9:59 ` David Laight 2016-12-16 9:59 ` [kernel-hardening] " David Laight 2016-12-16 9:59 ` David Laight 2016-12-16 15:57 ` Jason A. Donenfeld 2016-12-16 15:57 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-16 15:57 ` Jason A. Donenfeld 2016-12-15 20:30 ` [PATCH v5 4/4] random: " Jason A. Donenfeld 2016-12-15 20:30 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-16 3:03 ` [PATCH v6 0/5] The SipHash Patchset Jason A. Donenfeld 2016-12-16 3:03 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-16 3:03 ` [PATCH v6 1/5] siphash: add cryptographically secure PRF Jason A. Donenfeld 2016-12-16 3:03 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-16 3:03 ` [PATCH v6 2/5] secure_seq: use SipHash in place of MD5 Jason A. Donenfeld 2016-12-16 3:03 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-16 3:03 ` [PATCH v6 3/5] random: " Jason A. Donenfeld 2016-12-16 3:03 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-16 21:31 ` Andy Lutomirski 2016-12-16 21:31 ` [kernel-hardening] " Andy Lutomirski 2016-12-16 21:31 ` Andy Lutomirski 2016-12-16 3:03 ` [PATCH v6 4/5] md5: remove from lib and only live in crypto Jason A. Donenfeld 2016-12-16 3:03 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-16 3:03 ` [PATCH v6 5/5] syncookies: use SipHash in place of SHA1 Jason A. Donenfeld 2016-12-16 3:03 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-21 23:02 ` [PATCH v7 0/6] The SipHash Patchset Jason A. Donenfeld 2016-12-21 23:02 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-21 23:02 ` [PATCH v7 1/6] siphash: add cryptographically secure PRF Jason A. Donenfeld 2016-12-21 23:02 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-22 1:40 ` Stephen Hemminger 2016-12-22 1:40 ` [kernel-hardening] " Stephen Hemminger 2016-12-21 23:02 ` [PATCH v7 2/6] secure_seq: use SipHash in place of MD5 Jason A. Donenfeld 2016-12-21 23:02 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-21 23:02 ` [PATCH v7 3/6] random: " Jason A. Donenfeld 2016-12-21 23:02 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-21 23:13 ` Jason A. Donenfeld 2016-12-21 23:13 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-21 23:42 ` Andy Lutomirski 2016-12-21 23:42 ` [kernel-hardening] " Andy Lutomirski 2016-12-21 23:42 ` Andy Lutomirski 2016-12-22 2:07 ` Hannes Frederic Sowa 2016-12-22 2:07 ` [kernel-hardening] " Hannes Frederic Sowa 2016-12-22 2:07 ` Hannes Frederic Sowa 2016-12-22 2:09 ` Andy Lutomirski 2016-12-22 2:09 ` [kernel-hardening] " Andy Lutomirski 2016-12-22 2:09 ` Andy Lutomirski 2016-12-22 2:49 ` Jason A. Donenfeld 2016-12-22 2:49 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-22 2:49 ` Jason A. Donenfeld 2016-12-22 3:12 ` Jason A. Donenfeld 2016-12-22 3:12 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-22 3:12 ` Jason A. Donenfeld 2016-12-22 5:41 ` Theodore Ts'o 2016-12-22 5:41 ` [kernel-hardening] " Theodore Ts'o 2016-12-22 6:03 ` Jason A. Donenfeld 2016-12-22 15:58 ` Theodore Ts'o 2016-12-22 15:58 ` [kernel-hardening] " Theodore Ts'o 2016-12-22 16:16 ` Jason A. Donenfeld 2016-12-22 16:16 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-22 16:30 ` Theodore Ts'o 2016-12-22 16:36 ` Jason A. Donenfeld 2016-12-22 12:47 ` Hannes Frederic Sowa 2016-12-22 12:47 ` [kernel-hardening] " Hannes Frederic Sowa 2016-12-22 13:10 ` Jason A. Donenfeld 2016-12-22 15:05 ` Hannes Frederic Sowa 2016-12-22 15:12 ` Jason A. Donenfeld 2016-12-22 15:29 ` Jason A. Donenfeld 2016-12-22 15:33 ` Hannes Frederic Sowa 2016-12-22 15:33 ` [kernel-hardening] " Hannes Frederic Sowa 2016-12-22 15:41 ` Jason A. Donenfeld 2016-12-22 15:51 ` Hannes Frederic Sowa 2016-12-22 15:51 ` [kernel-hardening] " Hannes Frederic Sowa 2016-12-22 15:53 ` Jason A. Donenfeld 2016-12-22 15:54 ` Theodore Ts'o 2016-12-22 15:54 ` [kernel-hardening] " Theodore Ts'o 2016-12-22 18:08 ` Hannes Frederic Sowa 2016-12-22 18:13 ` Jason A. Donenfeld 2016-12-22 18:13 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-22 19:50 ` Theodore Ts'o 2016-12-22 2:31 ` Jason A. Donenfeld 2016-12-22 2:31 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-22 2:31 ` Jason A. Donenfeld 2016-12-21 23:02 ` [PATCH v7 4/6] md5: remove from lib and only live in crypto Jason A. Donenfeld 2016-12-21 23:02 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-21 23:02 ` [PATCH v7 5/6] syncookies: use SipHash in place of SHA1 Jason A. Donenfeld 2016-12-21 23:02 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-21 23:02 ` [PATCH v7 6/6] siphash: implement HalfSipHash1-3 for hash tables Jason A. Donenfeld 2016-12-21 23:02 ` [kernel-hardening] " Jason A. Donenfeld 2016-12-22 0:46 ` Andi Kleen 2016-12-22 0:46 ` [kernel-hardening] " Andi Kleen 2016-12-16 20:43 [PATCH v5 1/4] siphash: add cryptographically secure PRF Jason A. Donenfeld 2016-12-16 20:49 Jason A. Donenfeld 2016-12-16 21:25 ` George Spelvin
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