[Dtls-iot] Concluding Issue #24: Replacing TLS_PSK_WITH_AES_128_CCM_8 with TLS_PSK_WITH_AES_128_CCM

[Hannes Tschofenig <[e-mail]>]

Based on the discussion on the IRTF CFRG mailing list, see
http://www.ietf.org/mail-archive/web/cfrg/current/msg07138.html, I leave
the current recommendation unchanged.

I added a note with a reference to Section 6.2:

"
   Note that the
   shorted authentication tag increases the chance that an adversary
   with no knowledge of the secret key can present a message with a MAC
   that will pass the verification procedure.  The likelihoods of
   accepting forged data is explained in Section 5.3.5 of
   [SP800-107-rev1] and depends on the lengths of the authentication tag
   and allowed numbers of MAC verifications using a given key.
"

Ciao
Hannes