side channel

Allows an attacker to infer information about a secret by observing the non­functional characteristics of a program (e.g., execution time or memory) or mea­suring or exploiting the indirect coincidental effects of the system or its hardware (e.g., power consumption variation, electromagnetic emanations) while the pro­gram is executing. Most commonly, such attacks aim to exfiltrate sensitive infor­mation, including cryptographic keys.