[Freeswitch-users] ZRTP protocol measurement

[Jason White]

SERGE TUMBA <serget68 at msn.com> wrote:
> 
> I would like to know how to measure the performence of the zrtp using
> FreeSWITCH that connect two X-Lite softphones which use the zfone for
> encrypting voice packets on both end phones.

What do you want to know? There are almost as many performance measurements as
there are people doing the measuring. I would suggest measuring in whatever
way you normally would, comparing ZRTP sessions with sessions that do not
involve ZRTP, and seeing if there are performance differences that affect your
usage scenario.
> 
> Also, can someone contrast and compare ZRTP to SRTP focusing on these two
> protocol behaviors.

Have a look at http://www.zfone.com/ for a description of ZRTP. From an
operational perspective, the main difference is that in configuring SRTP, you
need to use TLS to secure the SIP signaling; otherwise, the cryptographic keys
are transmitted in the clear, which completely eliminates the security.
Setting up TLS securely requires a public-key infrastructure whereby each side
verifies the identity of the other.

In ZRTP, the negotiation takes place entirely in the RTP stream; there are
several protection mechanisms provided to prevent third-parties from
masquerading as one of the end-points (namely, key finger-prints, displayed to
the user as words that can be verified in the conversation, and
the use of mathematically related keys in subsequent sessions between the same
parties, but without diminishing security). No public-key infrastructure is
needed, hence no X.509 certificates or TLS are required.