SRTP has been designed to provide confidentiality, message authentication and replay protection to the RTP traffic. it is very useful for protecting against voice and video stream eavesdropping. however, a good key management protocol is needed to support SRTP, SDES, ZRTP, and DTLS-SRTP have been proposed as keying protocols, yet, from the literature, all of them have some drawbacks. so, in this paper, we propose a technique to enhance the SDES protocol to be more secure.