1. A processor-implemented method of performing a similarity measure of a plurality of privacy-protected data, comprising: selecting, in a processor, a first value and a first context related to one or more attributes of the first value; dividing, in the processor, the first value into a first plurality of substrings in an order preserving way; processing, in the processor, each substring of the first plurality of substrings through an obfuscation function to produce a first plurality of order preserved obfuscated substrings; selecting, in the processor, a second value and a second context related to one or more attributes of the second value; dividing, in the processor, the second value into a second plurality of substrings in the order preserving way; processing, in the processor, each substring of the second plurality of substrings through the obfuscation function to produce a second plurality of order preserved obfuscated substrings; comparing, in the processor, 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; comparing, in the processor, 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 determining a closeness degree between the first and second values from the context similarity measure and the value similarity measure.