SRTP
Click on the red underlined text to get to the source
... joins the service, he grabs the SEQ from the first seen SRTP
packet and prepends the ROC to build the index. If integrity
protection is used, the packet will be discarded. If there is no
...
... ROC value and initializes its local ROC to 1. Now, if an SRTP
packet prior to wraparound, i.e., with a SEQ lower than 0 (say,
SEQ ...
... SEQ = 0xffff), was delayed and reaches the receiver as the first
SRTP packet he sees, the receiver will initialize its highest
received sequence number ...
... sequence number, s_l, to 0xffff. Next, the receiver will
receive SRTP packets with sequence numbers larger than zero, and
will deduce that the SEQ ...
... 3GPP2 and 3GPP, where
SRTP is used for streaming media protection in their respective
multicast ...
... in the MKI (Master Key Identifier) field of each SRTP packet. This
has the advantage that the receiver immediately knows the entire
...
... authentication tag of a special integrity transform in selected
SRTP packets.
The benefit of this approach is that the functionality of fast and
...
... robust synchronization can be achieved as a separate integrity
transform, using the hooks existing in SRTP. Furthermore, when the
ROC is transmitted to the receiver ...
...
The value R is the rate at which the ROC is included in the SRTP
packets. Since the ROC consumes four octets, this gives the
possibility to use it sparsely.
...
...
When the receiver receives an SRTP packet, it processes the packet
according to RFC 3711prop except that during authentication ...
... transform to SRTCP. Hence, the transform SHALL only be applied to
SRTP, and SHALL NOT be used with SRTCP.
...
... integrity protection is offered, i.e., mode 3, the
following applies. The receiver's SRTP layer SHOULD ignore the ROC
value from the packet if the application layer ...
... removed from the packet before continued processing.
In this scenario, the application layer feedback to the SRTP layer
need not be on a per-packet basis, and it can consist merely of a
...
... boolean value set by the application layer and read by the SRTP
layer.
Thus, note the following difference. Using mode 2 will integrity ...
...
To have the ability to use different integrity transforms for SRTP
and SRTCP, which is needed in connection ...
... Type | Meaning | Possible values
-----+-----------------------------+----------------
14 | SRTP Auth. algorithm | see below
15 | SRTCP ...
... SRTCP Session Auth. key len | see below
18 | SRTP Authentication tag len | see below
19 | SRTCP ...
... RFC 3830prop, the following approach MUST be taken: If any of the
parameter types 14-19 (specifying behavior specific to SRTP or SRTCP)
and a corresponding general parameter (type 2, 3, or 11) are both
...
... Authentication algorithm" parameter
(type 2) is set to HMAC-SHA-1, and the "SRTP Auth. Algorithm" (type
14) is set to RCCm1 ...
... our knowledge, the only security consideration introduced here is
that the entire SRTP index (ROC || SEQ) will become public since it
...
... SEQ) will become public since it
is transferred without encryption. (In normal SRTP operation, only
the SEQ-part of the index is disclosed.) However, RFC 3711prop ...
... 3711prop does not
identify a need for encrypting the SRTP index.
It is important to realize that only every Rth packet is integrity ...
... RCCm2, and the value 4 for
RCCm3 have been registered in the SRTP auth alg namespace as
specified in Table 1 in Section 4.
...
... ROC transmission rate has been registered in the
SRTP Type namespace as specified in Table 2 in Section 4.
...
... namespace as specified in Table 2 in Section 4.
The values 14 to 19 have been registered in the SRTP Type namespace
according to Table 3 in Section 4.
...
... Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. Norrman, "The Secure Real-time Transport Protocol (SRTP)", RFC 3711prop, March 2004. ...