This paper presents a new approach for assessing the reliability of nanometer-scale devices prior to fabrication and a practical reliability architecture realization. A four-layer architecture exhibiting a large immunity to permanent as well as random failures is used. Characteristics of the averaging/thresholding layer are emphasized. A complete tool based on Monte Carlo simulation for a-priori functional fault tolerance analysis was used for analysis of distinctive cases and topologies. A full chip CMOS integrated design of the 128-bit AES cryptography algorithm with multiple cores that incorporate reliability architectures is shown.