1. A method for processing an input image securely, comprising a client computer and a server computer for performing steps of the method, comprising the steps of: acquiring, in a client computer, an input image I; generating a set of m random images, H 1 ,. .. , H m , and a coefficient vector, a=[a 1 ,. .. , a m ], such that the input image I is I=Σ i=1 m α i H j ; transferring the set of the random images to a server computer including a classifier y; determining, in the server computer, a set of m convolved random images H′, such that {H 1 ′=π 1 (H 1 *y)} i,1 m where * is the convolution operator and π 1 is a first random pixel permutation; transferring the set of convolved images to the client computer; determining, in the client computer, a set of m permuted image I′, such that I′=π 2 (Σ i=1 m α i H 1 ′), where π 2 is a second random pixel permutation; transferring the set of permuted image to the server computer; determining, in the server computer, a test image Ī such that Ī=αƒ(I′), wherein ƒ is a non-linear function, and α is a coefficient; and returning a true signal to the client computer if there exist a pixel q in the test image such that Ī(q)>0, otherwise return a false signal to the client computer to indicate whether or not the input image contains an object.