SRTP interoperability if any has questions

Hi all,

I am in the last stages of writing my master thesis and the topic is "SRTP interoperability". I have worked with cisco, alcatel, snom, and siemens also with some free softphones sofar. If any one have questions be my guest.

I would mean allot to me if you could help me with some issues about SRTP. I'm writing a report right now about it but I can't find any good SRTP compatible (soft) clients.

Just drop of line here of by direct communication MSN (tom_gilis******)

Hi,

Like DW, i'm also interested in what SIP softphones you tested. I only know of minisip. I also read about smartsip, but can't find that one on the net.

Hi all,

Sorry for late reply, for soft IPphones that speaks SRTP I managed to find only three, minisip, kphone(but must be compiled with --enable-srtp) and Snom360. Snom360 is a mirror image of the hardphone Snom360. As for smartphone I found the link here http://www.securesipclient.com/ but its NOT for free. If you like AES-256 but still not SRTP fully complient, then you might wana check Pacphone from packtizerlab.. very nice and neate phone (only for windoz). Another very nice phone is zfone, which is not a phone. I mean its kind of independant plugin that you install on your computer and it greps the call packets befor they are sent to Internet encrypt them then send them along. Zfone is opensource but not GPLed and works for MAC and Linux in the mean time.

Hope this helped
regrads,
Mohammad

hi
how do you find out if the pkt is indeed a SRTP pkt..ie how do u tell the diff between an RTP and SRTP pkt..there are only two new fields in the SRTP header and they are both optional (MKI and Description).

-- Siva.

SRTP can be used to encrypt and/or authenticate packet source. So if RTP packets were encrypted (SRTP-ized) then you will not be able to transform those packets to an understandable voice file. There are many tools which can deduce the audio content encapsulated in RTP packets like Cain&able, VOMIT, Voipong, wiresharke, .... etc.

If the packets are only integrity wise proteceted, then you will find a filed where the hash value for that packet is sent along the SRTP packet.

For more info, refer to RFC3711.

HTH,
mohammad