BugLink: http://bugs.launchpad.net/bugs/1592481

It gives significant improvements ( ~+15%) on some modes.

These code has been adopted from OpenSSL project in collaboration
with the original author (Andy Polyakov <appro@openssl.org>).
Signed-off-by: Paulo Flabiano Smorigo <pfsmorigo@linux.vnet.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
(cherry picked from commit 5ca55738)
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>