Abstract: A system, method and a device for offline authentication of transactions using mobile device, based on, analytic engine such as behavioral pattern detection are provided. The behavioral pattern can be for a specific person, for group of people with similar characteristics, or a combination of the two. The invention has the advantage over the prior art centralized authentication and fraud detection systems in that it more precise in identifying and preventing fraud in real time. The precision is better for both customer and merchant frauds. The present invention also requires fewer investments in infrastructure and uses less communication traffic when compared to the prior art.