The application relates to a method for computing a probabilistic encryption scheme for encrypting a data item in an electronic device including: computing a plurality of random bit strings in a computation cluster; sending the computed plurality of random strings to the electronic device; generating a random string (rE) for using in the encryption scheme in the electronic device using a subset of the plurality of the random strings computed in the computation cluster and encrypting the data item using the random string computed in the electronic device. The present application also relates to a corresponding system and corresponding computer program product including one or more computer readable media having computer executable instructions for performing the steps of the method.