An approach to cryptographic security uses a “fuzzy” credential, in contrast to a “hard” credential, to eliminate cryptographic algorithmic repeatability on a device that may be subject to physical attacks. By eliminating repeatability performed at an algorithmic (e.g., gate or software) level, a device inherently lacks one of the fundamental setup assumptions associated with certain classes of side channel, fault injection, timing, and related attacks, thus helps to protect the system against such attacks while preserving the cryptographic security of the system.