From: Tom Herbert <tom@herbertland.com>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Netdev <netdev@vger.kernel.org>,
kernel-hardening@lists.openwall.com,
LKML <linux-kernel@vger.kernel.org>,
Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com>,
"Daniel J . Bernstein" <djb@cr.yp.to>,
Linus Torvalds <torvalds@linux-foundation.org>,
Eric Biggers <ebiggers3@gmail.com>,
David Laight <David.Laight@aculab.com>
Subject: Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function
Date: Wed, 14 Dec 2016 15:14:01 -0800 [thread overview]
Message-ID: <CALx6S349hOFhnMgM_TgKXC1O7bmOvR87Nm=5B7_sNLEWiZU8Zg@mail.gmail.com> (raw)
In-Reply-To: <CAHmME9rpvf4tyDjZcJAJxMAW1LcqNm7DiquiYX0uQhRzDLbwqw@mail.gmail.com>
On Wed, Dec 14, 2016 at 2:56 PM, Jason A. Donenfeld <Jason@zx2c4.com> wrote:
> Hey Tom,
>
> On Wed, Dec 14, 2016 at 10:35 PM, Tom Herbert <tom@herbertland.com> wrote:
>> Those look good, although I would probably just do 1,2,3 words and
>> then have a function that takes n words like jhash. Might want to call
>> these dword to distinguish from 32 bit words in jhash.
>
> So actually jhash_Nwords makes no sense, since it takes dwords
> (32-bits) not words (16-bits). The siphash analog should be called
> siphash24_Nqwords.
>
Yeah, that's a "bug" with jhash function names.
> I think what I'll do is change what I already have to:
> siphash24_1qword
> siphash24_2qword
> siphash24_3qword
> siphash24_4qword
>
> And then add some static inline helpers to assist with smaller u32s
> like ipv4 addresses called:
>
> siphash24_2dword
> siphash24_4dword
> siphash24_6dword
> siphash24_8dword
>
> While we're having something new, might as well call it the right thing.
>
I'm confused, doesn't 2dword == 1qword? Anyway, I think the qword
functions are good enough. If someone needs to hash over some odd
length they can either put them in a structure padded to 64 bits or
call the hash function that takes a byte length.
>
>> Also, what is the significance of "24" in the function and constant
>> names? Can we just drop that and call this siphash?
>
> SipHash is actually a family of PRFs, differentiated by the number of
> SIPROUNDs after each 64-bit input is processed and the number of
> SIPROUNDs at the very end of the function. The best trade-off of speed
> and security for kernel usage is 2 rounds after each 64-bit input and
> 4 rounds at the end of the function. This doesn't fall to any known
> cryptanalysis and it's very fast.
I'd still drop the "24" unless you really think we're going to have
multiple variants coming into the kernel.
Tom
next prev parent reply other threads:[~2016-12-14 23:14 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-14 3:59 [PATCH v2 1/4] siphash: add cryptographically secure hashtable function Jason A. Donenfeld
2016-12-14 3:59 ` [PATCH v2 2/4] siphash: add convenience functions for jhash converts Jason A. Donenfeld
2016-12-14 3:59 ` [PATCH v2 3/4] secure_seq: use siphash24 instead of md5_transform Jason A. Donenfeld
2016-12-14 12:53 ` Jason A. Donenfeld
2016-12-14 13:16 ` Hannes Frederic Sowa
2016-12-14 13:44 ` Jason A. Donenfeld
2016-12-14 14:47 ` David Laight
2016-12-14 17:49 ` Jason A. Donenfeld
2016-12-14 17:56 ` David Miller
2016-12-14 18:06 ` Jason A. Donenfeld
2016-12-14 19:22 ` Hannes Frederic Sowa
2016-12-14 19:38 ` Jason A. Donenfeld
2016-12-14 20:27 ` Hannes Frederic Sowa
2016-12-14 20:12 ` Tom Herbert
2016-12-14 21:01 ` Jason A. Donenfeld
2016-12-14 3:59 ` [PATCH v2 4/4] random: use siphash24 instead of md5 for get_random_int/long Jason A. Donenfeld
2016-12-14 11:21 ` [PATCH v2 1/4] siphash: add cryptographically secure hashtable function Hannes Frederic Sowa
2016-12-14 13:10 ` Jason A. Donenfeld
2016-12-14 15:09 ` Hannes Frederic Sowa
2016-12-14 19:47 ` Jason A. Donenfeld
2016-12-15 7:57 ` Herbert Xu
2016-12-15 8:15 ` [kernel-hardening] " Daniel Micay
2016-12-14 12:46 ` Jason A. Donenfeld
2016-12-14 22:03 ` Hannes Frederic Sowa
2016-12-14 23:29 ` Jason A. Donenfeld
2016-12-15 8:31 ` Hannes Frederic Sowa
2016-12-15 11:04 ` David Laight
2016-12-15 12:23 ` Hannes Frederic Sowa
2016-12-15 12:28 ` David Laight
2016-12-15 12:50 ` Hannes Frederic Sowa
2016-12-15 13:56 ` David Laight
2016-12-15 14:56 ` Hannes Frederic Sowa
2016-12-15 15:41 ` David Laight
2016-12-15 15:53 ` Hannes Frederic Sowa
2016-12-15 18:50 ` Jason A. Donenfeld
2016-12-15 20:31 ` Hannes Frederic Sowa
2016-12-15 20:43 ` Jason A. Donenfeld
2016-12-15 21:04 ` Peter Zijlstra
2016-12-15 21:09 ` Hannes Frederic Sowa
2016-12-15 21:17 ` Hannes Frederic Sowa
2016-12-15 21:09 ` Peter Zijlstra
2016-12-15 21:11 ` [kernel-hardening] " Jason A. Donenfeld
2016-12-15 21:14 ` Linus Torvalds
2016-12-14 18:46 ` [PATCH v3 1/3] " Jason A. Donenfeld
2016-12-14 18:46 ` [PATCH v3 2/3] secure_seq: use siphash24 instead of md5_transform Jason A. Donenfeld
2016-12-14 21:44 ` kbuild test robot
2016-12-14 18:46 ` [PATCH v3 3/3] random: use siphash24 instead of md5 for get_random_int/long Jason A. Donenfeld
2016-12-14 21:56 ` kbuild test robot
2016-12-14 21:57 ` kbuild test robot
2016-12-15 10:14 ` David Laight
2016-12-15 18:51 ` Jason A. Donenfeld
2016-12-14 19:18 ` [PATCH v3 1/3] siphash: add cryptographically secure hashtable function Tom Herbert
2016-12-14 19:35 ` Jason A. Donenfeld
2016-12-14 20:55 ` Jason A. Donenfeld
2016-12-14 21:35 ` Tom Herbert
2016-12-14 22:56 ` Jason A. Donenfeld
2016-12-14 23:14 ` Tom Herbert [this message]
2016-12-14 23:17 ` Jason A. Donenfeld
2016-12-18 0:06 ` Christian Kujau
2016-12-14 23:30 ` Linus Torvalds
2016-12-14 23:34 ` Jason A. Donenfeld
2016-12-15 0:10 ` Linus Torvalds
2016-12-15 10:22 ` David Laight
2016-12-14 21:15 ` kbuild test robot
2016-12-14 21:21 ` Jason A. Donenfeld
2016-12-15 1:46 ` [PATCH v4 1/4] " Jason A. Donenfeld
2016-12-15 1:46 ` [PATCH v4 2/4] siphash: add N[qd]word helpers Jason A. Donenfeld
2016-12-15 1:46 ` [PATCH v4 3/4] secure_seq: use siphash instead of md5_transform Jason A. Donenfeld
2016-12-15 1:46 ` [PATCH v4 4/4] random: use siphash instead of MD5 for get_random_int/long Jason A. Donenfeld
2016-12-15 4:23 ` [PATCH v4 1/4] siphash: add cryptographically secure hashtable function kbuild test robot
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