Computer-implemented methods, apparati, and computer-readable media for thwarting computer attacks. A method embodiment of the present invention comprises the steps of examining (52) a digital certificate (20) presented by a server computer (2); compiling (53) a set of suspicion indications (31) gleaned from said examining step (52); feeding (54) said suspicion indications (31) to a trustworthiness calculation engine (30); and outputting from said engine (30) a trustworthiness factor (32) that determines whether SSL stripping is to be used (57) on communications with said server computer (2).