1. A non-transitory computer-readable medium embodying a program executable in at least one computing device, comprising: code that generates a request side channel pattern embodying a request to a plurality of machine instances executed in the at least one computing device, the request soliciting a plurality of response side channel patterns; code that detects the response side channel patterns in the at least one computing device; code that generates a plurality of responses as a function of the response side channel patterns; code that identifies individual ones of the machine instances as trusted machine instances, comprising: code that identifies a respective one of the machine instances as a trusted machine instance responsive to a respective one of the responses that are generated as a function of the response side channel patterns corresponding to a shared secret; code that identifies the respective one of the machine instances as an untrusted machine instance responsive to: the respective one of the machine instances not responding to the request side channel pattern, or the respective one of the responses not corresponding to the shared secret; code that configures one of the machine instances to operate in a trusted operational mode responsive to the machine instances comprising a quorum of trusted machine instances; code that configures the one of the machine instances to operate in an untrusted operational mode responsive to the machine instances failing to comprise the quorum of trusted machine instances; code that calculates an estimated resource usage of those of the machine instances corresponding to the response side channel patterns; and wherein the respective one of the machine instances is determined to have responded to the request side channel pattern responsive to the estimated resource usage meeting a threshold.