1. An apparatus for generating a signature of an input signal comprising: a plurality of computational cores coupled to the input signal, each core having properties that have at least some statistical independency from other of said computational cores, said properties are independent of each other core, wherein the properties of each of the plurality of computational cores include a first threshold and a second threshold, each of the plurality of computational cores generates, responsive to the input signal and said first threshold and said second threshold a first signature element and a second signature element respectively, said first signature element being a robust signature; wherein a plurality of said first signature elements comprise a first signature of the input signal and a plurality of said second signature elements comprise a second signature of the input signal, said first signature is generated respective of a robust selection criterion and said first threshold and said second signature is generated respective of said second threshold, wherein said first threshold is higher than said second threshold, said first signature being robust to noise and distortion.