1. A computer-implemented method for computing pairwise distance using a processor connected to an input/output interface and signal data stored in a memory connected to the processor via the interface connected to a sensor, comprising: transforming a first signal data into a first mapped signal data using an absolute distance preserving mapping stored in the memory; transforming a second signal data into a second mapped signal data using the absolute distance preserving mapping, such that a k-norm distance between the first mapped signal data and the second mapped signal data represents an absolute distance between the first signal data and the second signal data, wherein the second signal data is stored in a database of signal data, wherein elements of the first signal data and the second signal data are selected from the signal data corresponding to a finite alphabet, wherein the absolute distance preserving mapping maps an element of a first signal data or a second signal data to a vector having a size equals to a cardinality of the finite alphabet, wherein steps of the method are performed by the processor, wherein the k-norm distance is determined securely in an encrypted domain, wherein the second mapped signal data is stored in the database of signal data; and querying the database of mapped signal data using the k-norm distance with the first mapped signal data to determine at least one nearest neighbor signal data for a k-norm distance metric, and wherein the absolute distance preserving mapping, comprises: determining a position N of the element in an ordered sequence of symbols of the finite alphabet; determining values for each of N elements of the vector as a fractional power 1/k of positive increments in the finite alphabet, wherein k is a positive number, and determining values for subsequent elements of the vector as zero.