Charles,
Thanks for making the changes I suggested. I’ve got one follow-up
on the authentication item (see below).
Kind regards,
-Peter
-----Original Message-----
From: Charles Eckel (eckelcu) [mailto:eckelcu(_at_)cisco(_dot_)com]
Sent: Monday, June 01, 2015 12:39 PM
To: Hutton, Andrew; Jari Arkko; Peter Yee
Cc: draft-ietf-siprec-protocol(_dot_)all(_at_)tools(_dot_)ietf(_dot_)org;
gen-art(_at_)ietf(_dot_)org; IETF
Discussion Mailing List
Subject: Re: Gen-ART LC review of draft-ietf-siprec-protocol-16
Great comments. Please see comments inline.
Page 38, section 12.1, 1st paragraph, 2nd to last sentence: just
because
an SRS is compromised does not mean that it cannot be authenticated.
It
may very well be operating "correctly" and be able to authenticate,
yet
the compromise allows the attacker to obtain the (decrypted) RS.
Authentication does not imply that the SRS you are talking to is not
compromised. It only indicates the SRS possesses some form of
credential
that appears to identify it correctly.
Cannot argue with that and probably we should remove the sentence
starting "The risk of not authenticating the SRS...".
The two sentences expanding on the impact of the SRC and SRS not
performing mutual authentication are as follows:
"The risk of not authenticating the SRS is that the recording may be sent
to a
compromised SRS and that a sensitive call recording will be obtained
by an attacker. On the other hand, the risk of not authenticating
the SRC is that an SRS will accept calls from an unknown SRC and
allow potential forgery of call recordings."
Rather than removing, what if I change to the following:
"The risk of not authenticating the SRS is that the recording may
be sent to an entity other than the intended SRS, allowing a sensitive
call recording to be received by an attacker. On the other hand,
the risk of not authenticating the SRC is that an SRS will accept calls
from an unknown SRC and allow potential forgery of call recordings.
Cheers,
Charles
That does improve the text. Authentication helps to narrow the chance
that recordings are sent to the wrong SRS or received from an unknown
SRC, to the extent that the cryptographic keying materials that are used
in the authentication process are properly protected. I think the revised
text gives enough guidance without getting too deeply into the details of
how assurance of the security services is maintained, which is a problem
for all security protocols.