Simple Power Analysis (SPA)
Simple Power Analysis (SPA) is a technique used in computer security to attack cryptographic systems. It involves analyzing the power consumption or electromagnetic radiation of a device when it is performing cryptographic operations.
The idea is that when a device is performing cryptographic operations, it consumes different amounts of power or emits different levels of electromagnetic radiation depending on the values it is using to perform the calculation. By analyzing these variations in power or radiation, an attacker can make educated guesses about the secret key used in the encryption process.
SPA attacks can be performed on a variety of devices, including smart cards, embedded systems, and even PCs. The technique requires specialized equipment, but can be quite effective in breaking cryptographic systems.
To protect against SPA attacks, designers of cryptographic systems use techniques like randomizing the location of secret keys and introducing noise into the power lines to make it harder to analyze the power consumption.