SPI Map Sample Clauses

SPI Map. TIP supports the use of EKT to communicate and update SRTP contexts between transmitters and receivers in a multipoint session. EKT depends on the sharing of a set of security parameters between the transmitters and receivers of an SRTP session. Each security parameter set is uniquely identified by an index (SPI). The SPI is transmitted as part of each EKT tag to allow receivers to use the same security parameters used by the transmitter. TIP uses the SPIMAP packet to communicate the security parameter sets and indexes used in a multipoint session to all participants in the session. RTCP APP SPIMAP packet format +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |V=2|P|subtype=12| PT=APP=204 | length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SSRC | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | name=xcts | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Transmit NTP timestamp, most significant word | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Transmit NTP timestamp, least significant word | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SPI | SRTP PProfile | EKT PProfile | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SRTP Salt ... | | +-------------------------------+ | | KEK ... | +-------------------------------+ + | | | +-------------------------------+ | | Padding | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ RTCP APP Packet field definitions should follow [5] and: subtype: 5 bits MUST be set to ‘12’ to designate the SPIMAP packet type. name: 4 bytes MUST be set to the value ‘xcts’. SPIMAP Packet field definitions: transmit ntp timestamp: 64 bits The NTP time of the transmission of the request. This can be used by the receiver to detect out of order or duplicate requests. SPI: 2 bytes The session protection index. Note the least significant bit MUST be set to zero. SRTP PProfile: 1 byte This represents the SRTP Protection Profile as specified in [15]. Note that in [15] two bytes are used to represent the SRTP Protection Profile while TIP only uses the second byte. For example, the default SRTP crypto suite will be represented as 0x01 instead of {0x00, 0x01}. For this specification the default protection profile MUST be supported. The SRTP Protection Profile parameters for this profile (0x01) are: SRTP crypto suite: AES_128_CM SRTP master key length: 128 bits SRTP salt key length: ...