Side-Channel Attack
What Is a Side-Channel Attack?
In a direct software attack, an attacker tries to find a logical weakness in a program. In a side-channel attack, the attacker looks at how the hardware behaves while it is executing that program.
Think of a traditional wall safe. In this analogy, a logical attack would be trying to guess the combination, while a side-channel attack would be using a stethoscope to listen to the clicks of the tumblers as the dial turns. The clicks are an unintended physical signal (a side channel) that leaks information about the secret combination.
In the digital asset space, these attacks can target the moment a device signs a transaction. When doing so, a device might leak microscopic changes in electrical current or timing that an attacker can use to extract secret information, such as signing material or even a private key.
How Do Side-Channel Attacks Work?
Side-channel attacks focus on monitoring a device’s physical behavior. Common methods include:
- Power Analysis: Measuring the electrical current used by a chip, as different operations can consume different amounts of power.
- Electromagnetic Analysis: Capturing the radio waves or electromagnetic fields emitted by a circuit during operation.
- Timing Attacks: Measuring exactly how long a device takes to perform a specific task. If a wrong password check takes less time than a right one, an attacker can use that time difference to guess the secret.
- Thermal Analysis: Monitoring heat fluctuations across a chip’s surface to identify which components are active.
Side-channel attacks are an important part of the Ledger Donjon’s hardware-security research. As Ledger’s internal team of white-hat hackers, the Donjon utilizes side-channel analysis as one of its main research techniques to stress-test hardware and software across the entire crypto ecosystem. By using high-end oscilloscopes and custom sensors to measure signals from chips and circuits, they identify where sensitive data might be leaked through physical signals.
