Hi, i'm using the latest svn version of pjsua to communicate between two parties. I've set SRTP as mandatory for the media transport with the following parameters: --use-srtp 2 --srtp-secure 0 Everything is fine but Wireshark keep telling me "SRTP Payload with NULL encryption". Is that correct? Here is the snippet of the Offer SDP a=crypto:1 AES_CM_128_HMAC_SHA1_80 inline:VLDONbsbGl2Puqy+0PV7w/uGfpSPKFevDpxGsxN3 a=crypto:2 AES_CM_128_HMAC_SHA1_32 inline:lp5JGr/jKVzCzLyORdEMJjUPszZmioZ3zubVizTX and here is the encryption part of the Answer SDP a=crypto:1 AES_CM_128_HMAC_SHA1_80 inline:y71cYd6MyNqA9ywtm0rS2KBRDByG6/7vuQnyeL8T So my question, did pjsua used NULL encryption or AES_CM_128_HMAC_SHA1_80 as suggested in the Answer-SDP? Another question, when the caller uses (--use-srtp 1) and the callee has (--use-srtp 2) the call is always unencrypted. Is there a way to change that behavior in pjsua? Thanks in advance for any help Michael

Hi Michael, On 1/31/08, Michael Bradley Jr <mbradley.jr@gmail.com> wrote: > Hi, > > i'm using the latest svn version of pjsua to communicate between two parties. > I've set SRTP as mandatory for the media transport with the following parameters: > > --use-srtp 2 --srtp-secure 0 > > Everything is fine but Wireshark keep telling me > "SRTP Payload with NULL encryption". > Is that correct? > > Here is the snippet of the Offer SDP > > a=crypto:1 AES_CM_128_HMAC_SHA1_80 inline:VLDONbsbGl2Puqy+0PV7w/uGfpSPKFevDpxGsxN3 > a=crypto:2 AES_CM_128_HMAC_SHA1_32 inline:lp5JGr/jKVzCzLyORdEMJjUPszZmioZ3zubVizTX > > and here is the encryption part of the Answer SDP > a=crypto:1 AES_CM_128_HMAC_SHA1_80 inline:y71cYd6MyNqA9ywtm0rS2KBRDByG6/7vuQnyeL8T > > So my question, did pjsua used NULL encryption or AES_CM_128_HMAC_SHA1_80 as > suggested in the Answer-SDP? > I don't know how Wireshark can find out the cipher from RTP packets (AFAIK you'd have to see the SDP negotiation), but I think it's wrong. The RTP packets should be encrypted, and you can verify this by saving the (G711) payload to a file and see the contents. What Wireshark version are you using? Mine doesn't seem to even know about SRTP. > Another question, when the caller uses (--use-srtp 1) and the callee has > (--use-srtp 2) the call is always unencrypted. Is there a way to change that > behavior in pjsua? > Somehow it did not happen here (I'm using r1761). The call is rejected with 406/Not Acceptable. cheers, -benny > Thanks in advance for any help > > Michael