Don't enforce the old HMAC key size requirement in FIPS 198 Sec. 3.

Don't enforce the old HMAC key size requirement in FIPS 198 Sec. 3.

This requirement has been removed in FIPS 198-1.

R=rsleevi@chromium.org
BUG=none
TEST=none
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=126674

[Ryan Sleevi, 2012-03-13 19:50:25]

Sad to see the stronger check go, but LGTM.

FWIW, the wording was changed because of the SHA-2/SHA-3 suites, where less than
half was still "good enough". SHA-1's minimum is still 'at least' half (although
with recent attacks, I seem to recall it's even greater).

[wtc, 2012-03-13 19:51:54]

rsleevi: please doublecheck I read FIPS 198-1 Section 3
and NIST SP 800-107 Sections 5.3.2 and 5.3.4 correctly.
Thanks.

[commit-bot: I haz the power, 2012-03-14 01:39:18]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/wtc@chromium.org/9695058/1

[commit-bot: I haz the power, 2012-03-14 04:06:54]

Try job failure for 9695058-1 (retry) on win_rel for step "browser_tests".
It's a second try, previously, step "browser_tests" failed.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_rel&nu...

[commit-bot: I haz the power, 2012-03-14 14:59:33]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/wtc@chromium.org/9695058/1

[commit-bot: I haz the power, 2012-03-14 15:50:55]

Try job failure for 9695058-1 (retry) on linux_rel for step
"remoting_unittests".
It's a second try, previously, step "remoting_unittests" failed.
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_rel&...

[wtc, 2012-03-14 17:58:34]

On 2012/03/13 19:50:25, Ryan Sleevi wrote:
> Sad to see the stronger check go, but LGTM.
> 
> FWIW, the wording was changed because of the SHA-2/SHA-3 suites, where less
than
> half was still "good enough". SHA-1's minimum is still 'at least' half
(although
> with recent attacks, I seem to recall it's even greater).

Thank you for the comment.

FIPS 198 was indeed issued earlier than SHA-2 (FIPS 180-2), though
by only a few months (March vs. August of 2002).  It is strange that
FIPS 198 didn't take into account the imminent SHA-2 algorithms.

It's also strange that SP 800-107 compares the key size (or rather,
the key's security strength) with 2L instead of L/2.  (It is a
different kind of comparison though.)  If we follow the recommendation
of SP 800-107, there is no need to use HMAC with SHA-256 at the
128-bit security level.