Security Preconditions for Session Description Protocol (SDP) Media Streams

Session Description Protocol (SDP) Capability Negotiation

“…The easiest protection against such an attack is to not offer use of the non-secure media stream in the actual configuration; however, that may in itself have undesirable side effects: If the answerer does not support the secure media stream and also does not support the capability negotiation framework, then negotiation of the media stream will fail. Alternatively, SDP security preconditions [RFC5027] can be used. This will ensure that media is not flowing until session negotiation has completed and hence the selected configuration is known.…”

Connectivity Preconditions for Session Description Protocol (SDP) Media Streams

“…The connectivity precondition type is defined by the string "conn", and hence we modify the grammar found in RFC 3312 [RFC3312] and RFC 5027 [RFC5027] as follows:…”

“…Quality of Service, for example, may be required for the media stream; this can be addressed by use of the "qos" precondition defined in RFC 3312 [RFC3312]. Similarly, successful security parameter negotiation may be another prerequisite; this can be addressed by use of the "sec" precondition defined in RFC 5027 [RFC5027].…”

On the Applicability of Various Multimedia Internet KEYing (MIKEY) Modes and Extensions

“…To cope with the early media problem, there are further approaches to describe security preconditions [RFC5027]; i.e., certain preconditions need to be met to enable voice data encryption. One example, for instance, is that a scenario where a provisional response, containing the required MIKEY parameter, is sent before encrypted media is processed.…”