1. A computer-implemented method for thwarting computer attacks, said method comprising the steps of: examining a digital certificate presented by a server computer in response to a secure sockets layer (SSL) session initiated by a client computer; compiling a set of suspicion indications gleaned from said examining step; feeding said suspicion indications to a trustworthiness calculation engine; outputting from said engine a trustworthiness factor that indicates a suspicion that the digital certificate is part of a computer attack; determining whether to use SSL stripping on communications with said server computer responsive to an evaluation of said trustworthiness factor; and responsive to a positive determination to use SSL stripping, performing SSL stripping on communications between said client computer and said server computer.