A method and system for service provision, including: a web browser in a first communications device (e.g. a personal computer) running a script from a source (e.g. a remote web server) trusted by the first communications device's user; sending, from the first device to a second communications device (e.g. a smartphone) that has a web server, a user-verified indication of the trusted source; sending, from the first device to the second device: a service request, for a service required by script currently running on the web browser, and an indication of the source of the current script; the second device comparing the indicated source of the current script to the indicated trusted source; and the second device providing the requested service only if the indicated source of the current script corresponds to the indicated trusted source.