30. The computer program product of claim 29 , further comprising a program code for adding a sequence identifier to each of the first plurality of substrings to preserve the order of the first plurality of substrings.
29. A computer program product comprising a storage device having program codes stored thereon, wherein the program codes, when read and executed by a processor, result in the processor performing a similarity measure of a plurality of privacy-protected data, the program codes comprising: a program code for selecting a first value and a first context related to one or more attributes of the first value; a program code for dividing the first value into a first plurality of substrings in an order preserving way; a program code for processing each substring of the first plurality of substrings through an obfuscation function to produce a first plurality of order preserved obfuscated substrings; a program code for selecting a second value and a second context related to one or more attributes of the second value; a program code for dividing the second value into a second plurality of substrings in the order preserving way; a program code for processing each substring of the second plurality of substrings through the obfuscation function to produce a second plurality of order preserved obfuscated substrings; a program code for comparing the first and second plurality of order preserved obfuscated substrings, and determining a value similarity measure for a comparison of the first and second values based on the comparison of the first and second plurality of order preserved obfuscated substrings; a program code for comparing the first context and the second context, and determining a context similarity measure for the first context and the second context based on the comparison of the first and second contexts, wherein the context similarity measure indicates a validity of the comparison between the first and second values; and a program code for determining a closeness degree between the first and second values from the context similarity measure and the value similarity measure.