Side-channel attack

In computer security, a side-channel attack is a type of security exploit that uses information inadvertently leaked by a system—such as timing, power consumption, or electromagnetic or acoustic emissions—to gain unauthorized access to sensitive information. These attacks differ from those targeting flaws in the design of cryptographic protocols or algorithms (notwithstanding the fact that cryptanalysis may identify vulnerabilities relevant to both types of attacks). Some side-channel attacks require technical knowledge of the internal operation of the system, others such as differential power analysis are effective as black-box attacks. The rise of Web 2.0 applications and software-as-a-service has also significantly raised the possibility of side-channel attacks on the web, even when transmissions between a web browser and server are encrypted (e.g. through HTTPS or WiFi encryption), according to researchers from Microsoft Research and Indiana University. Attempts to break a cryptosystem by deceiving or coercing people with legitimate access are not typically considered side-channel attacks: see social engineering and rubber-hose cryptanalysis. General classes of side-channel attack include: Cache attack – attacks based on attacker's ability to monitor cache accesses made by the victim in a shared physical system as in virtualized environment or a type of cloud service. Timing attack – attacks based on measuring how much time various computations (such as, say, comparing an attacker's given password with the victim's unknown one) take to perform. Power-monitoring attack – attacks that make use of varying power consumption by the hardware during computation. Electromagnetic attack – attacks based on leaked electromagnetic radiation, which can directly provide plaintexts and other information. Such measurements can be used to infer cryptographic keys using techniques equivalent to those in power analysis or can be used in non-cryptographic attacks, e.g. TEMPEST (aka Van Eck phreaking or radiation monitoring) attacks. Acoustic cryptanalysis – attacks that exploit sound produced during...