11. Obfuscation in SAS-RCS/RBS
by: saaiqSAS
Last Updated: 27/2/2025
In the obfuscation step of both SAS-RCS and SAS-RBS, random objects are inserted into the original
data based on a ratio for_every:add. This process is referred to as "Data Size Increase"
throughout the ROSET project. The ratio functions as follows: For every for_every number
of objects, add additional random objects are introduced. For example, if the ratio is
2:3 for SAS-RCS, it means that for every 3 characters, 2 random characters
are added. Example 11.1 below demonstrates this for SAS-RCS.
Example 11.1: Data Size Increase for RCS
Ratio: 2:3
Data: hello
Output: he###ll###o
'#', in this case, represents a random character.
In SAS-RBS, the objects refer to bits. Therefore, for the ratio 3:2, it means that for
every 3 bits, 2 additional random bits are inserted. Example 11.2
below demonstrates this for SAS-RBS.
Example 11.2: Data Size Increase for RBS
Ratio: 3:2
Data: 1101011011010100
Output: 110||101||101||101||010||0
'|' represents a random bit.
The random objects added are selected from the Dynamic Key and are inserted exactly as shown
in the examples above, following the ratio format. There is no need to insert them at random positions,
as in SAS-RCS, because the subsequent steps—character-wise shuffling for SAS-RCS and the SAS-ROS step for
SAS-RBS—will obscure the distinction between the original data and the added random objects.