Technology and Standards
ISTK, InterStream Transit Keys, or simply "transit keys" secure access through both mediated and unmediated Internet bottlenecks. Unlike, ISPKs, the InterStream Transit Keys are only for securing access with guaranteed quality through the transit portion of the network. The keys are temporary (one-time use), lasting only the stream block length session to ensure network integrity and security. Using an embedded key management system within network equipment, the network operator always retains control of their ISTKs and never has to share them directly with outside parties. Cambix's Secure Mediation Controller (SMC) manages the keys per mediation policies established by the network operator.
Streams may be blocked and ISTKs may not be granted to a sender if the bottlenecks lack sufficient capacity for the stream. In addition, ISPs must insure that their Stream Blocking Probability (SBP) remains below the InterStream required maximum threshold to use the Association's service mark for their network.
ISTKs represent a significant advancement over traditional packet marking mechanisms such as those used with DiffServ. Traditional mechanisms are primarily designed for intra-carrier QoS with packets being marked or re-marked at administrative boundaries. ISTKs allow for inter-carrier QoS by enabling a common clearinghouse and transit key authority to issue to the keys. By creating a "root" authority, the media industry can insure that only those streams who adhere to InterStream Terms of Service (ITOSA) may be granted access to premium bandwidth.