Source: Real-Time Innovations ( Dr. Gerardo Pardo-Castellote, Ph.D.)
The RTPS specification allows implementations to send implementation-specific RTPS sub-messages inside an RTPS message. These submessages are distinguished by having submessageId's within a specific range.
Prior to DDS security skipping implementation-specific RTPS sub-messages was very efficient requiring only the receiver to jump their length indicated in. the header.
However with DDS security the submessages can be encrypted inside a SRTPS_PREFIX/SUFFIX envelope this requires the receiver to always decrypt them even if it will end up skipping them.
An extreme, but likely common case is when the SRTPS_PREFIX/SUFFIX contains exclusively implementation-specific RTPS sub-messages which makes the effort to decrypt the RTPS message fruitless.
A way to resolve this would be to designate a flag in the SRTPA_PREFIX submessage to indicate that the content contains only vendor-specific submessages. A receiver can use this flag to skip the whole RTPS message avoiding the effort to decrypt i n the event that the sender vendorId does not match the receiver's.
The proposal therefore is to designate the leftmost flag of the SRTPS_PREFIX submessage to indicate it contains only "vendor specific content".
Reported: DDS-SECURITY 1.1b1 — Thu, 8 Jun 2023 04:35 GMT
Updated: Thu, 8 Jun 2023 13:21 GMT