A. membership function. S – Shaped fuzzy membership function

A. Fuzzy
Based Approach:

The concepts of fuzzy sets are merely an extension to the generic set theory. In fuzzy sets the
gradual  assessment
 of data is 
done using a
 suitable fuzzy membership  function fuzzification  of 
original  data
 to
 fuzzy set  preserves  privacy and  relativity between data9. This approach enhances the efficiency of clustering by
decreasing required
number of passes. The fuzzy membership function used also influences the processing time. Thus, selecting proper fuzzy
membership function can improve the efficiency of algorithm
and also aid in overcoming most of the limitations
stated in the previous section. In our work, data masking
is achieved using S-Shaped membership function. S –
Shaped fuzzy membership function is given
by

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……..(1)

Where x – is value of the sensitive attribute, a &
b –
is minimum and maximum value in the sensitive attribute. The only
limitation of this approach is that it can only map the
values between 0 and 1. Still, it can be used to mask the data having
their domain from 0 to 1.

 

B.
 Rail-fence Method :

This technique is mostly
applied to categorical data where in the original data is written
row/column-wise and the transformed data is fetched by traversing along column/row wise respectively.

 

C.
 Map Range (Rosetta
Code) :

Map  Range  method  of  normalization
 performs
 mapping  of  original
 data  to  a  range (mostly for mapping large values to a small range) given by the user. This method is used for numerical data. The formula is given as follows: Given two ranges, a1, a2 and b1, b2; then a value s in range a1, a2 is linearly mapped to a value t in range b1, b2 when:

 

     …….………………………………(2)

 

D.
Masking
Outs:

Masking
out is replacing certain parts of the data with specific characters(X or *). Care
should be taken in masking out appropriate data by
not masking required information. If
the required information is masked then the entire field becomes useless. This technique is generally used in credit card transfers and in internet banking. For example, credit card
number 5289 7895 1236 4598 can be masked as 5289 XXXX
XXXX 4598. It would be
tedious for applying different
patterns for the same field.