Sivupolkuhyökkäykset

Sivupolkuhyökkäykset, or side-channel attacks, are a class of security exploits that aim to extract sensitive information by observing the physical implementation of a cryptographic system. Instead of directly attacking the mathematical algorithms, these attacks exploit information leakage that occurs during the computation. This leakage can manifest in various forms, including timing variations, power consumption, electromagnetic radiation, or even acoustic emissions.

For example, a timing attack might measure the time it takes for a cryptographic operation to complete. Differences in execution time for different inputs could reveal information about the secret key. Power analysis attacks monitor the power consumed by a device while it performs encryption. These power fluctuations are often correlated with the operations being performed and the data being processed, allowing an attacker to infer key bits. Electromagnetic analysis intercepts the electromagnetic waves emitted by electronic devices, which can also carry information about internal computations.

Side-channel attacks are particularly relevant for hardware implementations of cryptography, such as smart cards, secure microcontrollers, and embedded systems. Because these devices often operate in environments where physical access is possible or where sophisticated monitoring equipment can be deployed, they are more vulnerable. The effectiveness of these attacks depends on the attacker's ability to precisely measure and analyze the leaked side-channel information. Countermeasures against side-channel attacks often involve making the physical implementation more uniform, so that the side-channel leakage is independent of the secret data or operations. This can include techniques like constant-time execution, power randomization, or masking.