Re: Remove little-used algorithms from IKEv2

[Dan McDonald <danmcd@east.sun.com>]

> I found it to be about 15% faster than SHA-1, and that on a big endian
> machine.

OTOH, if your big-endian machine can dance the little-endian dance better,
you get noticeable speedup.  The UltraSPARC-tuned MD5 is 30% faster than the
non-UltraSPARC-tuned MD5.  Using your 15% improvement as a base...

		M is MD5
		S is SHA-1
		M' is tuned MD5

	M = 0.85S

	M' = 0.70M

	M' / 0.70 = 0.85S

	M' = 0.70 * 0.85S

	M' = 0.59S

If you want to see what I mean precisely, utter this on a sun4m (e.g. SPARC
20) machine running Solaris 7 or later:

	dis -F MD5Transform /kernel/misc/md5

and utter this on a sun4u (e.g. any UltraSPARC box)

	dis -F MD5Transform /platform/sun4u/kernel/misc/md5

and note the instruction count savings.

> That number makes sense given the structure of the two
> algorithms.  So, somewhat better, yes.  "Far better", no.

See my math above for SW and dancing the little-endian dance.

> In hardware implementations, the two tend to be pretty close, and
> usually faster than the encryption transform so it doesn't matter
> which you chose as far as performance goes.

Now _this_ I'll buy.

Dan