Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Wed, 21 Dec 2016 15:42:33 +0100
From: "Jason A. Donenfeld" <Jason@...c4.com>
To: Eric Dumazet <eric.dumazet@...il.com>
Cc: George Spelvin <linux@...encehorizons.net>, "Theodore Ts'o" <tytso@....edu>, 
	Andi Kleen <ak@...ux.intel.com>, David Miller <davem@...emloft.net>, 
	David Laight <David.Laight@...lab.com>, "Daniel J . Bernstein" <djb@...yp.to>, 
	Eric Biggers <ebiggers3@...il.com>, Hannes Frederic Sowa <hannes@...essinduktion.org>, 
	Jean-Philippe Aumasson <jeanphilippe.aumasson@...il.com>, kernel-hardening@...ts.openwall.com, 
	Linux Crypto Mailing List <linux-crypto@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>, 
	Andy Lutomirski <luto@...capital.net>, Netdev <netdev@...r.kernel.org>, 
	Tom Herbert <tom@...bertland.com>, Linus Torvalds <torvalds@...ux-foundation.org>, 
	Vegard Nossum <vegard.nossum@...il.com>
Subject: Re: HalfSipHash Acceptable Usage

Hi Eric,

I computed performance numbers for both 32-bit and 64-bit using the
actual functions in which talking about replacing MD5 with SipHash.
The basic harness is here [1] if you're curious. SipHash was a pretty
clear winner for both cases.

x86_64:
[    1.714302] secure_tcpv6_sequence_number_md5# cycles: 102373398
[    1.747685] secure_tcp_sequence_number_md5# cycles: 92042258
[    1.773522] secure_tcpv6_sequence_number_siphash# cycles: 70786533
[    1.798701] secure_tcp_sequence_number_siphash# cycles: 68941043

x86:
[    1.635749] secure_tcpv6_sequence_number_md5# cycles: 106016335
[    1.670259] secure_tcp_sequence_number_md5# cycles: 95670512
[    1.708387] secure_tcpv6_sequence_number_siphash# cycles: 105988635
[    1.740264] secure_tcp_sequence_number_siphash# cycles: 88225395

>>> 102373398 > 70786533
True
>>> 92042258 > 68941043
True
>>> 106016335 > 105988635
True
>>> 95670512 > 88225395
True

While MD5 is probably faster for some kind of large-data
cycles-per-byte, due to its 64-byte internal state, SipHash -- the
"Sip" part standing "Short Input PRF" -- is fast for shorter inputs.
In practice with the functions we're talking about replacing, there's
no need to hash 64-bytes. So, SipHash comes out faster and more
secure.

I also haven't begun to look focusedly at the assembly my SipHash
implemention is generating, which means there's still window for even
more performance improvements.

Jason


[1] https://git.zx2c4.com/linux-dev/tree/net/core/secure_seq.c?h=siphash-bench#n194

Powered by blists - more mailing lists

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.