sidechannels

Side-channel attacks are a class of security exploits that do not target a system's inherent algorithmic weaknesses but rather exploit information leaked during the physical implementation of a cryptosystem. Instead of attempting to break the encryption directly through mathematical means, side-channel attacks observe and analyze physical characteristics of the device executing the cryptographic operations. These characteristics can include the timing of operations, power consumption, electromagnetic radiation, acoustic emissions, or even the heat generated.

By monitoring these physical emanations, an attacker can infer sensitive information about the secret keys or internal state of the system. For example, analyzing the power consumption of a smart card while it performs encryption can reveal patterns correlated with the bits of the secret key being processed. Similarly, timing attacks measure the duration of cryptographic operations, which can vary based on the secret data, to deduce information. These attacks are particularly concerning because they can compromise systems even if the underlying cryptographic algorithms are mathematically sound and considered secure.

Countermeasures against side-channel attacks typically involve modifying the hardware or software implementation to reduce or obfuscate the leakage of physical information. Techniques such as constant-time execution, power consumption balancing, noise injection, and shielding are employed to make it more difficult for attackers to extract meaningful data from physical emanations. The effectiveness of these countermeasures often depends on the specific side-channel attack being considered and the sensitivity of the information being protected.