1. A method of dynamically assigning a role to a user in a distributed computing environment, said method comprising the steps of: defining one or more roles, each role characterized by a threshold trust value; defining one or more attributes, each attribute characterized by a weight coefficient; determining current values of said one or more attributes for said user; calculating a current level of trust for said user, said current level of trust based on said values of said one or more attributes and said weight coefficients of said one or more attributes; and assigning a role to said user based on said current level of trust and said threshold values.