srtp-utils 1.4.4+20100615~dfsg-1build1 (amd64 binary) in ubuntu precise

 SRTP is a security profile for RTP that adds confidentiality, message
 authentication, and replay protection to that protocol. It is specified
 in RFC 3711.
 .
 LibSRTP provides an implementation of the Secure Real-time Transport
 Protocol (SRTP), the Universal Security Transform (UST), and a
 supporting cryptographic kernel.
 .
 This package contains a few simple binaries using libsrtp.