Encryption of Header Extensions in the Secure Real-time Transport Protocol (SRTP)

The Secure Real-time Transport Protocol (SRTP) provides authentication, but not encryption, of the headers of Real-time Transport Protocol (RTP) packets. However, RTP header extensions may carry sensitive information for which participants in multimedia sessions want confidentiality. This document provides a mechanism, extending the mechanisms of SRTP, to selectively encrypt RTP header extensions in SRTP. This document updates RFC 3711, the Secure Real- time Transport Protocol specification, to require that all future SRTP encryption transforms specify how RTP header extensions are to be encrypted.