Deterring an attack on a tamper-resistant application program may be accomplished by loading a plurality of agents and starting a plurality of processing threads, each thread executing one of the agents, concurrently executing each agent substantially in parallel to produce a processing result for each agent for an iteration of a stage of protocol processing, storing each processing result in an entry in a buffer associated with each agent, and repeating the executing and storing actions for multiple iterations of the protocol processing. When one of the agents stores a processing result in a last entry of the agent's buffer, the processing results from the first entries in the buffers are combined to produce a combined result, and if the combined result indicates an error, failure semantics may be executed.